FS725 Manual
User Manual:
Open the PDF directly: View PDF .
Page Count: 115
Download | |
Open PDF In Browser | View PDF |
FS725 Rubidium Frequency Standard Operation and Service Manual !"#$%&'()*+,--.'/0)12) 321140*5)6'7*589-:18*'#;$<# =>-1)?'@;$81H3(3IJ-+''C'',,,IG>81H3(3IJ-+ 7-K4:8L>G'M'"$$"'N4'3(36'O1JI /55'(8L>GP'()P):0).I Version 1.1 (11/2005) FS725 Rubidium Frequency Standard Table of Contents 1 Table of Contents Specifications Q2GK2GP D:-1G'=*1)5 ()*:'=*1)5 S)1):*5 3 R ; ; T Overview 6 Operation =-,): U*:+%2K 7-11)JG8-1 3(3'81PG:2+)1GP D:)V2)1J4'7-1G:-5 !'KKP'81K2G 8 < < < # !$ !! Monitor and Control 3)GG81L'2K'(3"R" S)GG81L'7-11)JG). W)PG81L'J-11)JG8-1 W):+81*5'K:-L:*+ (2N8.82+'3G*GP D*JG-:4'3)GG81LP'G*N /1*5-L'Y*52)P'G*N !'KKP'J-1G:-5'G*N 7-5-:).'N-E)P D85)'Z)12 [)5K'Z)12 W):+81*5'K:-L:*+ 14 !; !; !T !T !X !B !< !< !< !# !# !# Calibration U8G>'*'9:)V2)1J4'J-21G): U8G>'*'!'KKP':)9):)1J) W8+)%G*L'-99P)G'K*:*+)G): 20 "$ "" "; Circuit description =(3!$'J-11)JG-: !'KKP'81K2G \-JH'*1.'!'KKP'-2GK2G (3%"R"'81G):9*J) D:-1G'K*1)5'\]&P =-,):'P2KK58)P !$'Z[^'-2GK2G T'Z[^'-2GK2G 38L1*5P'G-'-KG8-1'J*:.P QKG8-1'J*:.P "T "T "X "X "X "B "B "< "< "< Component parts list D3B"T'+*81'N-*:. D3B"T'-KG8-1'N-*:. D3B"T'>*:.,*:) R$ R! R" Circuit Schematics Z*81'N-*:.'@!_"A Z*81'N-*:.'@"_"A QKG8-1'N-*:.' 35 RX RB R< Addendum: PRS10 Manual FS725 Rubidium Frequency Standard 2 Table of Contents FS725 Rubidium Frequency Standard Specifications 3 Specifications Standard outputs W,-'!$'Z[^'P81)',*0)P6'-1)'T'Z[^'P81)',*0)6'-1)'!'KKP ,8G>'!$'`P',8.G> Optional outputs aK'G-'R'.8PG:8N2G8-1'+-.25)P6')*J>',8G>'9-2:'!$'Z[^6'-1)'T Z[^6'*1.'-1)'!'KKP 1 pps output "IT'Y'81G-'T$'b'6'T'Y'81G-'>8L>'8+K).*1J)6'!$'`P'K25P)',8.G> Sine outputs $IT'Y:+P6'c!$d'@!I;!'YKK'-:'eB'.f+A Phase noise g%!R$'.fJ_[^'F'!$'[^ (5 MHz & 10 MHz) g%!;$'.fJ_[^'F'!$$'[^ g%!T$'.fJ_[^'F'!'H[^ g%!TT'.fJ_[^'F'!$'H[^ Spurious g%!$$'.fJ'@,8G>81'!$$'H[^A Harmonics g%X$'.fJ Return loss h"T'.f'F'!$'Z[^ Accuracy cT'× !$%!!' Aging gT'× !$%!!'@+-1G>546'*9G):'!PG'+-1G>A gT'× !$%!$'@4)*:546'*9G):'98:PG'4)*:A Allan variance g"'× !$%!!'@!'PA g!'× !$%!!'@!$'PA g"'× !$%!"'@!$$'PA Holdover B"'>-2:'3G:*G2+'!'@!×!$%!!A Frequency retrace cT'i!$%!!'@B"'>:P'-99'G>)1'B"'>:P'-1A Settability gT'× !$%!" Trim range c"'× !$%#'@K-G'-:'N4'$%T'Y&7'81K2GA c$IT'KK+'@08*'(3%"R"A Warm-up time gX'+812G)P'@G8+)'G-'5-JHA gB'+812G)P'@G8+)'G-'!'i'!$%#A FS725 Rubidium Frequency Standard 4 Specifications Front Panel Indicators Power jQ1k',>)1'/7'K-,):'8P'*KK58). Locked jQ1k',>)1'9:)V2)1J4'8P'5-JH).'G-':2N8.82+'>4K):981)'G:*1P8G8-1 1 PPS input f581HP',8G>')*J>'!'KKP':)9):)1J)'81K2G'*KK58).'G-':)*:'K*1)5 1 PPS sync jQ1k',>)1'!'KKP'-2GK2G'8P'P41J>:-18^).'G-',8G>81'c!`P'-9'!'KKP'81K2G Receive f581HP'j-1k',>)1'(3%"R"'J>*:*JG):P'*:)':)J)80).'N4'D3B"T Send f581HP'j-1k',>)1'(3%"R"'J>*:*JG):P'*:)'P)1G'N4'D3B"T Rear Panel Connections FREQ ADJ $%T'Y&7'G-'*.l2PG'9:)V2)1J4'N4'e_%'$I$$"'KK+'@1-:+*554 21J-11)JG).A 1 PPS Input Q1) !$$'Hb'81K2GI'()V28:)P'7ZQ3'5)0)5'K25P)P'@$%T'Y&7IA O9'*1 )EG):1*5'!'KKP'81K2G'8P'*KK58).6'5-JH'8P'+*81G*81).'N)G,))1'G>)'!'KKP 81K2G'*1.'!'KKP'-2GK2G',8G>'J-+K2G):'*.l2PG*N5)'1*G2:*5'G8+)'J-1PG*1G 9:-+'<'+812G)P'G-'!<'>-2:PI'@&)9*25G'8P'"I"T'>-2:PIA 10 MHz Out W,-'8P-5*G).'T$'b'!$'Z[^'P81)'-2GK2GP 5 MHz Out Q1)'T$'b'T'Z[^'P81)'-2GK2G 1 PPS Out Q1)'T$'b'K25P)'-2GK2GI Optional ]*J>'-KG8-1'N-*:.'K:-08.)P'9-2:'!$'Z[^6'-1)'T'Z[^'*1.'-1)'!'KKP -2GK2GPI'aK'G-'R'N-*:.P'+*4'N)'81PG*55).'*G'G>)'G8+)'-9'-:.):I Relays Z*E'J2::)1G6'R/I'3=&W6'1-:+*554%-K)1'-:'1-:+*554%J5-P).I'Z*4'N) ,8:).'81'K*:*55)5',8G>'-G>):':)5*4P'G-'j,8:)%-:k'*'P81L5)'*5*:+I Rb Lock ()5*4'PG*G2P'+*GJ>)P'9:-1G'K*1)5'j\-JH).k'\]&I 1 PPS ()5*4'PG*G2P'+*GJ>)P'9:-1G'K*1)5'j!'KKP'P41Jk'\]& RS-232 #'K81'J-11)JG-:'J-198L2:).'*P'&7]6'#X$$'N*2.I'/'U81.-,Pm'7-1G:-5 K:-L:*+'8P'K:-08.).I FS725 Rubidium Frequency Standard Specifications 5 Environmental Operating temperature e!$'n7'G-'e;$'n7 Storage temperature %TT'n7'G-'e8K FS725 Rubidium Frequency Standard 6 Overview Overview W>)'D3B"T'8P'*'PG*1.%*5-1)'!$'Z[^'9:)V2)1J4'PG*1.*:.',8G>'*1')PG8+*G).'"$%4)*:'*L81L'-9 5)PP'G>*1'$I$$T'KK+I'W>)'218G'81G)L:*G)P'*1'3(3'=(3!$'(2N8.82+'D:)V2)1J4'3G*1.*:.6'* 2180):P*5'/7'81K2G'K-,):'P2KK546'*1.'.8PG:8N2G8-1'*+K5898):P'81'*'>*59%,8.G>'"a'J>*PP8P'@RITk >)8L>GAI'W>)'218GpP'5-,'*L81L')58+81*G)P'G>)'1)).'9-:'*1')EG):1*5'9:)V2)1J4':)9):)1J)'81'+*14 *KK58J*G8-1Pq'>-,)0):'218GP'J*1'K>*P)%5-JH'G-'*1')EG):1*5'!'KKP'S=3'P8L1*5'9-:'*L)5)PP K):9-:+*1J)'-:'K):8-.8J'J*58N:*G8-1'*P':)V28:).I W>)'D3B"T'K:-08.)P')EJ)KG8-1*554'5-,'K>*P)'1-8P)'T'Z[^'r'!$'Z[^'P81)'-2GK2GP'*P',)55'*P *'5-,%l8GG):'!'KKP'-2GK2GI'W>)'!$'Z[^'-2GK2GP'>*0)'*'K>*P)'1-8P)'-9'g%!R$'.fJ_[^'*G'!$[^ -99P)G'9:-+'J*::8):6'.:-KK81L'G-'gs!TT'.fJ_[^'*G'!$'H[^'-99P)GI'W>)'/55*1'Y*:8*1J)'8P'5)PP G>*1'"E!$%!!'*G'-1)'P)J-1.'*1.'"'× !$%!"'*G'!$$'P)J-1.PI'W>)'!'==3'WW\'-2GK2G'>*P'5)PP'G>*1 !1P'-9'l8GG):'*1.'+*4'N)'P)G',8G>'!1P':)P-52G8-1I W>)'PG*1.*:.'D3B"T'>*P'G,-'!$'Z[^'-2GK2GP6'-1)'T'Z[^'-2GK2G6'*1.'-1)'!'==3'-2GK2GI'aK G-'G>:))'.8PG:8N2G8-1'+-.25)P'J*1'N)'*..).'G-'G>)'218GI']*J>'+-.25)'K:-08.)P'P8E'*..8G8-1*5 -2GK2GP?'9-2:'!$'Z[^'-2GK2GP6'-1)'T'Z[^'-2GK2G6'*1.'-1)'!'==3'-2GK2GI'U8G>'G>:))'+-.25)P 81PG*55).'G>)'D3B"T',855'K:-08.)'9-2:G))1'!$'Z[^'-2GK2GP6'9-2:'T'Z[^'-2GK2GP6'*1.'9-2:'! ==3'-2GK2GP6')*J>',8G>'G>)'P*+)'5-,'K>*P)'1-8P)6'>*:+-18J'.8PG-:G8-1'*1.'l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l2PG'8GP 9:)V2)1J4'G-'+*81G*81'G>)'K>*P)'5-JH'N)G,))1'G>)'!'KKP'81K2G'*1.'G>)'!'KKP'-2GK2GI'W>)'K>*P) 5-JH'*5L-:8G>+'2P)P'*1'*.l2PG*N5)'1*G2:*5'G8+)'J-1PG*1G'@9:-+'*'<'+812G)P'G-'!<'>-2:PA',>8J> +*4'N)'*.l2PG).'08*'G>)'(3%"R"I W,-'*5*:+':)5*4P'*:)'K:-08.).'G-'P8L1*5'G>)'PG*G2P'-9'G>)'=(3!$':2N8.82+'9:)V2)1J4'PG*1.*:. *1.'8GP'P41J>:-18^*G8-1'G-'*1')EG):1*5'!'KKP'81K2GI'f-G>':)5*4P'*:)'3=&W'K:-08.81L'N-G> 1-:+*554%-K)1'*1.'1-:+*554%J5-P).'-K):*G8-1I'3)0):*5'G>-2P*1.'=(3!$P'>*0)'N))1'-K):*G81L 81'0*:8-2P'Q]Z'*KK58J*G8-1P',8G>'*'.)+-1PG:*G).'ZWfD'P)0):*5'>21.:).'G>-2P*1.'>-2:P'*1. P-'*'+*5921JG8-1'-9'G>)'=(3!$'8P'0):4'2158H)54I'O1'G>)')0)1G'-9'*'9*852:)'G>)'*5*:+':)5*4',855 *JG80*G)'N2G'G>)'!$'Z[^'-2GK2G',855'N)'K:-08.).'N4'G>)'218GpP'-0)18^).'37%J2G'!$'Z[^ J:4PG*5'-PJ855*G-:',8G>'G4K8J*5'*L81L'-9'$I$T'KK+_4)*:I W>)'D3B"T',855'981.'*KK58J*G8-1'*P'*1'*2G-1-+-2P'9:)V2)1J4'PG*1.*:.'81'08:G2*554'*14 J*58N:*G8-1'*1.'(r&'5*N-:*G-:8)P',>):)'K:)J8P8-1'G8+)'-:'9:)V2)1J4'+)*P2:)+)1GP'*:)'+*.)6 -:'81'*14'-G>):'9*J858G4':)V28:81L'*1'*JJ2:*G)'9:)V2)1J4'PG*1.*:.I'W>)'5-,'J-PG'-9'G>)'218G6 FS725 Rubidium Frequency Standard Overview 7 G-L)G>):',8G>'8GP')EG:)+)54'5-,'*L81L6',855'*55-,'J2PG-+):P'G-'.)K5-4'K:)J8P8-1'9:)V2)1J4 :)9):)1J)P'G>:-2L>-2G'*'9*J858G4',8G>-2G'G>)'1)).'G-'81PG*55'J*N5)P'-:'*1G)11*PI FS725 Rubidium Frequency Standard 8 Operation Operational Description Power W>)'218G'8P'K-,):).'9:-+'G>)'/7'+*81PI'W>)'2180):P*5'81K2G'K-,):'P2KK54'*JJ-++-.*G)P *14'0-5G*L)'81'G>)':*1L)P'#$'G-'!R"Y/7'-:'!BT'G-'"X;Y/7',8G>'*'9:)V2)1J4'81'G>)':*1L)'-9 ;B'G-'XR[^I'W>):)'8P'1-'K-,):'P,8GJ>'*P'G>)'218G'P>-25.'N)'5)9G'j-1k'*55'G>)'G8+)I'W>) :2N8.82+'9:)V2)1J4'PG*1.*:.'8P'-K):*G81L'*1.'-2GK2GP'*:)'*0*85*N5)',>)1)0):'/7'K-,):'8P *KK58).I Warm-up W>)'9:-1G'K*1)5'j=QU](k'\]&'P>-25.'N)'-1',>)1)0):'K-,):'8P'*KK58).'G-'G>)'218GI'W>) 9:-1G'K*1)5'j\Q7t]&k'\]&'P>-25.'J-+)'-1',8G>81'P8E'+812G)P'*9G):'K-,):'8P'*KK58).'89'G>) 218G'8P'PG*:G).'9:-+':--+'G)+K):*G2:)I'U*:+%2K'*1.'5-JH81L',855'G*H)'5-1L):'89'G>)'218G'8P PG*:G).'9:-+'*'5-,):'G)+K):*G2:)I'QK):*G8-1'-9'G>)'j\Q7t]&k'\]&'J-::)PK-1.P'G-'G>)'PG*G) -9'G>)':)*:'K*1)5'j(f'\Q7tk'*5*:+':)5*4I'U>)1'K-,):'8P'98:PG'*KK58).6'G>)'j\Q7t]&k'\]& ,855'N)'-99'*1.'G>)'j(f'\Q7t]&k':)5*4',855'N)'81'G>)'j*5*:+k'K-P8G8-1I'Q1J)'G>)'218G ,*:+P'2K'*1.'5-JHP'8GP'J:4PG*5'-PJ855*G-:'G-'G>)':2N8.82+'K>4P8JP'K*JH*L)6'G>)'j\Q7t]&k \]&',855'G2:1'-1'*1.'G>)'j(f'\Q7tk':)5*4',855'+-0)'G-'G>)'1-1%*5*:+'PG*G)I W>)'-2GK2G'9:)V2)1J4',855'N)'*N-2G'"$$'KK+'N)5-,'1-+81*5',>)1'K-,):'8P'98:PG'*KK58).'G-'* J-5.'218GI'W>)'9:)V2)1J4',855'L:*.2*554'J-10):L)'-1'!$'Z[^'*P'G>)'218G',*:+P'2KI'/9G): *N-2G';'+812G)P'@G4K8J*554A'G>)'218G',855':)*J>'-K):*G81L'G)+K):*G2:)'*1.'5-JH'G>)'J:4PG*5 -PJ855*G-:'G-'G>)':2N8.82+'>4K):981)'G:*1P8G8-1I'U8G>81'P)0)1'+812G)P6'G>)'218G',855'N)'5-JH). G-',8G>'$I$$!KK+'-9'!$'Z[^I Connection to other instruments /55'-9'G>)'-2GK2GP'-1'G>)':)*:'-9'G>)'D3B"T'>*0)'*'P-2:J)'8+K).*1J)'-9'T$'b'*1.'*:)'81G)1.). G-'.:80)'T$'b'5-*.PI'381J)'G>)'-2GK2GP'>*0)'*'P-2:J)'8+K).*1J)'-9'T$'b6'G):+81*G8-1'81G-'* T$'b'5-*.'8P'1-G'J:8G8J*5'81'+-PG'*KK58J*G8-1PI'S)1):*5546'G>)'*+K58G2.)',855'*KK:-E8+*G)54 .-2N5)'89'G>)'-2GK2G'8P'1-G'G):+81*G).'81G-'*'T$'b'5-*.I'=:-K):54'G):+81*G81L'81G-'*'T$'b'5-*. ,855':).2J)'J>*11)5%G-%J>*11)5'J:-PP%G*5H'*1.',855':).2J)'G>)'K:-N*N54'-9'+25G8K5)'G:8LL):81L -1'G>)'!'KKP'-2GK2GI O9'*'P81L5)'T'Z[^'-:'!$'Z[^'-2GK2G'8P'j.*8P4%J>*81).k'G-'P)0):*5'81PG:2+)1GP'8G',855'N) 8+K-:G*1G'G>*G'*55'-9'G>)'81PG:2+)1GP'>*0)'*'>8L>%8+K).*1J)'81K2G'@h!'HbA'*1.'G>*G'*'T$'b G):+81*G-:'N)'K5*J).'*G'G>)'9*:')1.'-9'G>)'581)I'S)1):*5546'8G'8P'N)GG):'K:*JG8J)'G-'2P)'*'P)K*:*G) -2GK2G'G-')*J>'81PG:2+)1G'G-'*0-8.'J:-PP%G*5H'*1.'*+K58G2.)'0*:8*G8-1P'.2)'G-'21J):G*81 5-*.81L'*1.'PG*1.81L',*0)P'*5-1L'G>)'581)I Z*14'81PG:2+)1GP',>8J>'L)1):*G)'-:'+)*P2:)'K:)J8P)'9:)V2)1J8)P'-:'G8+)%81G):0*5P'>*0)'*'!$ Z[^'81K2G6'2P2*554'5-J*G).'-1'G>)':)*:'-9'G>)'81PG:2+)1GI'Z-PG'-9'G>)P)'81PG:2+)1GP'*JJ)KG'* P81)'81K2G',8G>'G>)'*+K58G2.)'K:-08.).'N4'G>)'D3B"TI'3-+)G8+)P'*':)*:'K*1)5'P,8GJ>'-:'9:-1G K*1)5'J-198L2:*G8-1'+)12'8P':)V28:).'G-'jG)55k'G>)'81PG:2+)1G'G-'2P)'G>)'!$'Z[^'81K2G'*P'* FS725 Rubidium Frequency Standard Operation 9 :)9):)1J)'81PG)*.'-9'2P81L'G>)'81PG:2+)1GpP'-,1'G8+)'N*P)I'O+K:-0).'*JJ2:*J4'J*1'N) *J>8)0).'N4'2P81L'G>)'D3B"T'*P'*1')EG):1*5'G8+)'N*P)'G-'*55'-9'G>)'81PG:2+)1GP'81'*'K*:G8J25*: 5*N-:*G-:4I'O1'*..8G8-16'*55')::-:P'*PP-J8*G).',8G>'G>)'J*58N:*G8-1'-9'*1'81.808.2*5'81PG:2+)1GpP G8+)'N*P)'*:)')58+81*G).I Connection to SRS Instruments SR620 Time Interval Counter. W>8P'81PG:2+)1G'8P'jG-5.k'G-'2P)'G>)')EG):1*5'!$'Z[^'81K2G 08*'G>)'9:-1G'K*1)5'7QuDOS'+)12I'W-'J-198L2:)'G>)'3(X"$'G-'2P)'*1')EG):1*5'G8+)'N*P) K:)PP'G>)'3]\'H)4'81'G>)'7QuDOS'P)JG8-1'-1J)'G-'.8PK5*4'7QuDOS'+)12P6'G>)1'K:)PP'3]\ -1)'+-:)'G8+)'G-'P)5)JG'G>)'jJ/\k'+)126',>8J>',855'95*P>',>)1'P)5)JG).I'=:)PP'G>)'3]W'H)4 G,8J)'G-'*JJ)PP'G>)'jJ\-J'3-2:J]k'P2N+)12I'=:)PP'G>)'*::-,'H)4P'8++).8*G)54'G-'G>)'5)9G'-9 G>)'7QuDOS'+)12'@81'G>)'37Q=]'/u&'7[/(W'P)JG8-1A'G-'P)5)JG'j:]/:k6',>8J>'8P'G>)':)*: K*1)5'G8+)'N*P)'81K2GI'=:)PP'G>)'3]W'H)4'81'G>)'7QuDOS'P)JG8-1'-1J)'+-:)'G-'0):894'G>) )EK)JG).'G8+)'N*P)'9:)V2)1J4'@T'Z[^'-:'!$'Z[^AI'=:)PP'G>)'*::-,'H)4P'G-'P)5)JG'G>) 9:)V2)1J4'-9'G>)'G8+)'N*P)',>8J>'4-2',855'N)'2P81LI DS345 Synthesized Function Generator. W>)'&3R;T'*2G-+*G8J*554'.)G)JGP'G>)'*KK58J*G8-1'-9'*1')EG):1*5'G8+)'N*P)'*1.'K>*P)'5-JHP'G8GI'/9G):'*KK5481L'*'T'Z[^'-:'!$'Z[^'P81)'G-'G>)':)*:'K*1)5'G8+)'N*P)'81K2G6'*'9:-1G'K*1)5 81.8J*G-:',855'G2:1'j-1kI DG535 Digital Delay Generator /':)*:'K*1)5'P,8GJ>'8P'2P).'G-'PK)J894'*1')EG):1*5'!$'Z[^'G8+)'N*P)'81K2GI'3-+)':)08P8-1P'-9 G>)'&STRT':)V28:).'*'!$'Z[^'PV2*:)',*0)'81K2G6'*1.'+*4'1-G'-K):*G)'K:-K):54',8G>'G>)'!$ Z[^'P81)',*0)'-2GK2G'9:-+'G>)'D3B"TI'W>)'2P):'P>-25.'0):894'K:-K):'-K):*G8-1'-9'G>) &STRT',>)1'5-JH).'G-'*1')EG):1*5'G8+)'N*P)',8G>'*1'3(X"$'W8+)'O1G):0*5'7-21G):I FS725 Rubidium Frequency Standard 10 Operation Direct Frequency Control of the FS725 W>)'9:)V2)1J4'-9'G>)':2N8.82+'>4K):981)'G:*1P8G8-1'8P'*.l2PG).'08*'*'P+*55'+*L1)G8J'98)5.'81 G>)'K>4P8JP'K*JH*L)I'W>)'+*L18G2.)'-9'G>)'+*L1)G8J'98)5.'8P'P)G'N4'G>)'+8J:-J-1G:-55):'81'G>) =(3!$I'W>)'9:)V2)1J4'-99P)G'8P'V2*.:*G8J'81'G>)'+*L1)G8J'98)5.'N2G'98:+,*:)'81'G>)'=(3!$ 581)*:8^)P'G>)'*.l2PG+)1GI'W>)'+8J:-J-1G:-55):':)*.P'G>)'K-P8G8-1'-9'*'J*58N:*G8-1 K-G)1G8-+)G):'@*JJ)PP8N5)'-1'G>)'P8.)'K*1)5'-9'G>)'81PG:2+)1GA6'-:':)PK-1.P'G-'P-9G,*:) J-++*1.P'08*'G>)'(3%"R"6'G-'P)G'G>)'+*L1)G8J'98)5.',>8J>'J-1G:-5P'G>)'-K):*G81L'9:)V2)1J4I W>)'-K):*G81L'9:)V2)1J4'+*4'N)'.8:)JG54'J-1G:-55).'-0):'G>)':*1L)'-9'c$I$$"KK+'81'9-2: ,*4P? !I f4'G>)'*.l2PG+)1G'-9'*'!T'G2:1'K-G)1G8-+)G):'*JJ)PP8N5)'-1'G>)'P8.)'-9'G>)'81PG:2+)1GI W2:181L'G>)'K-G)1G8-+)G):'J5-JH,8P)',855'81J:)*P)'G>)'9:)V2)1J4'N4'*N-2G'$I$$"T[^'K): G2:1I'W>)'*.l2PG+)1G'K:-J).2:)'8P'.)G*85).'81'G>)'J*58N:*G8-1'P)JG8-1I "I f4'*KK5481L'*'0-5G*L)'81'G>)':*1L)'-9'$'G-'T'Y&7'G-'G>)':)*:'K*1)5'D(]v'/&w'fu7I'W>) 1-+81*5'0-5G*L)'8P'"IT$'Y&7I'W>)'0-5G*L)'-1'G>8P'fu7'J-::)PK-1.P'G-'G>)'K-P8G8-1'-9'G>) !T'G2:1'K-G)1G8-+)G):'.)PJ:8N).'*N-0)I'W>)'0-5G*L)'+*4'N)'-0)::8..)1'N4'*'2P):'81K2GI W>)'G2181L':*G)'*G'!$'Z[^'8P'$I$$<'[^_0-5GI'W>)'81K2G_P-2:J)'8+K).*1J)'8P'N)G,))1'!$ Hb'*1.'RT'Hb'.)K)1.81L'-1'G>)'K-G)1G8-+)G):'K-P8G8-1I RI f4'P-9G,*:)'J-++*1.'08*'G>)'(3%"R"I'W>)'3D'@3)G'D:)V2)1J4A'K*:*+)G):'*55-,P'G>)'2P): G-'P)G'G>)'9:)V2)1J4',8G>'*':)P-52G8-1'-9'!?!$%!"I'W>)'K*:*+)G):'>*P'*':*1L)'-9'c"$$$ ,>8J>'*55-,P'9:)V2)1J4'J-1G:-5'-0):'G>)':*1L)'-9'c$I$$"'KK+I'W>)'K-P8G8-1'-9'G>) 9:)V2)1J4'*.l2PG+)1G'K-G)1G8-+)G):'8P'2P).'G-'P)G'G>)'3D'K*:*+)G):'21G85'*'3D'J-++*1. 8P':)J)80).'08*'G>)'(3%"R"'-:'21G85'K>*P)'5-JH81L'G-'*1')EG):1*5'P-2:J)'8P'*JG80*G).'N4'G>) *KK58J*G8-1'-9'!'KKP'81K2GP'G-'G>)':)*:'K*1)5'fu7I'7-1G:-5'8P':)G2:1).'G-'G>)'K-G)1G8-+)G): ,>)1'G>)'K-,):'8P'J4J5).I'&)G*85P'*:)'*0*85*N5)'81'G>)'=(3!$'-K):*G8-1'*1.'P):08J) +*12*5I ;I f4'P-9G,*:)'J*58N:*G8-1'08*'G>)'ZQ'@Z*L1)G8J'Q99P)GA'K*:*+)G):I'W>)'ZQ'K*:*+)G):'8P P2++).'81'V2*.:*G2:)',8G>'G>)'3D'K*:*+)G):'G-'J-1G:-5'G>)'9:)V2)1J4'-9'-K):*G8-1I'/G'G>) 9*JG-:46'G>)'ZQ'K*:*+)G):'8P'J*58N:*G).'P-'G>*G'G>)'218G',855'-K):*G)'*G'!$'Z[^',8G>'*1 3D'0*52)'-9'$I'W>)'3D'K*:*+)G):'8P'P)G'N4')8G>):'G>)'K-G)1G8-+)G):'-:'08*'(3%"R" J-++*1.P6'*1.',855'N)'^):-',>)1'G>)'K-G)1G8-+)G):'8P'J)1G):).I'W>)'ZQ'K*:*+)G):'+*4 N)'*.l2PG).'*1.':)G*81).'81'G>)'=(3!$']]=(QZ6'*55-,81L'9:)V2)1J4'J*58N:*G8-1'08*'G>) (3%"R"I'&)G*85P'*:)'*0*85*N5)'81'G>)'=(3!$'-K):*G8-1'*1.'P):08J)'+*12*5I FS725 Rubidium Frequency Standard Operation 11 Using an External 1 pps Reference. W>)'D3B"T'>*P'P2998J8)1G'*JJ2:*J4'@$I$$T'KK+')PG8+*G).'-0):'"$'4)*:PA'G>*G'+-PG'2P):P',855 1-G'1)).'G-'2P)'*1')EG):1*5'G8+81L':)9):)1J)I'[-,)0):6'9-:'J:8G8J*5'*KK58J*G8-1P':)V28:81L'* 9:)V2)1J4'*JJ2:*J4',>8J>'8P'N)GG):'G>*1'!i!$%#6'-:'G-'K:-08.)'J-1G812-2P'G:*J)*N58G46'G>) D3B"T'+*4'N)'5-JH).'G-'*1')EG):1*5'!'KKP':)9):)1J)I U>)1'*'K:)J8P)'!'KKP'P8L1*5'8P'*KK58).'G-'G>)'!'KKP'81K2G'-1'G>)':)*:'K*1)5'-9'G>)'D3B"T6'G>) :2N8.82+'9:)V2)1J4'PG*1.*:.',855'K>*P)%5-JH'G-'G>)'P8L1*5I'W>)'!'KKP'P8L1*5'2P2*554'J-+)P 9:-+'*'S=3':)J)80):',>8J>'J*1'>*0)'*'5-1L%G):+'*JJ2:*J4'-9'*'9),'K*:GP'81'!$!"I'f)J*2P)'G>) PG*N858G4'-9'G>)'!'KKP':)9):)1J)'81'G>)'P>-:G'G):+'J*1'N)'+2J>',-:P)'G>*1'G>*G'-9'G>)'=(3!$6 G>)'=(3!$'K>*P)%5-JHP'G-'G>)'!'KKP',8G>'*1'*.l2PG*N5)'G8+)'J-1PG*1G'-9'9:-+'<'+812G)P'G-'!< >-2:P6',>8J>':).2J)P'G>)'1-8P)'-9'G>)':)9):)1J)'!'KKP'N4'*0):*L81LI W>)':)*:%K*1)5'!'KKP'81K2G'G-'G>)'D3B"T'8P'*'>8L>'8+K).*1J)'81K2G'G>*G'8P'.8PJ:8+81*G).'N4'* 7ZQ3'3J>+8GG'G:8LL):6',8G>'*'G>:)P>-5.'-9'*N-2G'"ITY&7I'OG'8P'8+K-:G*1G'G-'K:-08.)'*'!'KKP 81K2G',8G>'7ZQ3'5)0)5P'@$%TY&7IA'W>)'!'KKP'81K2G'+*4'1-G',-:H':)58*N54',8G>'*'WW\'81K2G -:'G>)'!'KKP'-2GK2G'9:-+'*1-G>):'81PG:2+)1G'@P2J>'*P'*1-G>):'D3B"TA'89'G>)'P8L1*5'8P G):+81*G).'81G-'T$'bI'@W>)'!'KKP'9:-+'*1-G>):'D3B"T',855',-:H'981)6'K:-08.81L'8G'8P'1-G G):+81*G).'81G-'T$'bIA /'J5*PP8J*5'"1.'-:.):'K>*P)%5-JH'J-1G:-5'5--K'8P'8+K5)+)1G).'81'98:+,*:)I'W>)'jK>*P) J-+K*:*G-:k'8P'*'G8+)%G*LL81L'J8:J28G',>8J>'+)*P2:)P'G>)'G8+81L'-9'G>)'!'KKP'81K2G',8G> 1*1-P)J-1.':)P-52G8-1I'/'K:-K-:G8-1*5%81G)L:*5'K>*P)%5-JH'*5L-:8G>+'J-1G:-5P'G>)'9:)V2)1J4 -9'G>)':2N8.82+'9:)V2)1J4'PG*1.*:.'08*'G>)'K*:*+)G):'3D'@3)G'D:)V2)1J4AI'u-:+*5546'G>)'3D K*:*+)G):'8P'P)G'N4'G>)'98:+,*:)':)*.81L'G>)'J*58N:*G8-1'K-G)1G8-+)G):I'[-,)0):6',>)1'*'! KKP'P8L1*5'8P'P))16'G>)'K>*P)%5-JH'*5L-:8G>+'x>8l*JHPp'G>)'3D'K*:*+)G):'G-'K>*P)%5-JH'G>) :2N8.82+'9:)V2)1J4'PG*1.*:.'G-'G>)'!'KKP'81K2GI W>)'5-JH81L'*5L-:8G>+'-9'G>)'=(3!$'K:-J)).P'*P'9-55-,P? •'W>)'!'KKP'=\\'8P')1*N5).',>)1'G>)'218G'8P'G2:1).%-1'-:':)PG*:G).'89'G>)'=\'K*:*+)G):'PG-:). 81'G>)'218GpP']]=(QZ'8P'j!kI'@W>8P'8P'G>)'.)9*25G'0*52)IA •'W>)'=\\',855'N)L81'G-'J-1G:-5'G>)'9:)V2)1J4'-9'G>)':2N8.82+'9:)V2)1J4'PG*1.*:.',>)1'"TX J-1P)J2G80)'jL--.k'!'KKP'81K2GP'@8I)I6'!'KKP'81K2GP',>8J>'*:)',8G>81'±"$;<'1P'-9'G>)'98:PG G8+)%G*L':)P25G6'+-.25-'!'PA'*:)':)J)80).I •'/9G):':)J)8081L'"TX'J-1P)J2G80)'jL--.k'!'KKP'81K2GP6'G>)'!'KKP'-2GK2G'K25P)'8P'+-0).'GJ-81J8.)',8G>'G>)'5*PG'-9'G>)'"TX'G8+)%G*L'0*52)PI'W>)'9:-1G'K*1)5'j!'KKP'P41J>:-18^).k'\]& ,855'G2:1'-16'*P'G>)'!'KKP'81K2G'*1.'G>)'!'KKP'-2GK2G'*:)'1-,',8G>81'c!`P'-9')*J>'-G>):I •'W>)'218G',855'5-JH'G>)'9:)V2)1J4'-9'G>)'=(3!$'G-'G>)'jL--.k'!'KKP'81K2G'K25P)PI'jf*.k'! KKP'81K2GP'@!'KKP'81K2GP',8G>'G8+)%G*LP'L:)*G):'G>*1'!6$";'1P'9:-+'G>)'5*PG'jL--.k'!'KKP 81K2GA',855'N)':)l)JG).I'/'.8L8G*5'985G):'8P'2P).'G-'8+K5)+)1G'G>)'J5*PP8J*5'"1.'-:.): FS725 Rubidium Frequency Standard 12 Operation K:-K-:G8-1*5_81G)L:*5'K>*P)'5-JH'5--KI'W>)'-2GK2G'-9'G>)'.8L8G*5'985G):'J-1G:-5P'G>)'9:)V2)1J4'-9 -K):*G8-1'08*'G>)'3D'@P)G'9:)V2)1J4A'J-++*1.6',>8J>'8P'2K.*G).'-1J)'*'P)J-1.I •'W>)'=\\',855'N)'*N-:G).'*1.':)PG*:G).'89'G>):)'*:)'"TX'J-1P)J2G80)'jN*.k'!'KKP'81K2GPI @W>8P'J-25.'>*KK)1'89'G>)'!'KKP'81K2G'8P'+-0).'P2..)154'N4'+-:)'G>*1'!6$";'1PIA W>)'G8+)'J-1PG*1G'-9'G>)'=\\'8P'P)G',8G>'G>)'=W'J-++*1.I'W>)'.)9*25G'0*52)'8P'<6'K:-08.81L'* x1*G2:*5'G8+)'J-1PG*1Gp'-9'*N-2G'"I"T'>-2:PI'W>)'=W'0*52)'P>-25.'N)'P)G'G-'*'P+*55):'12+N): 89'G>)'!'KKP':)9):)1J)'8P'0):4'J5)*16'9-:')E*+K5)6'89'G>)'!'KKP':)9):)1J)'8P'K:-08.).'N4'*1-G>): D3B"TI'aP81L'*'P+*55):'=W'0*52)',855':).2J)'G>)'K)*H%G-%K)*H'0*:8*G8-1P'@xP,8++81LpA N)G,))1'G>)'!'KKP'81K2G'*1.'G>)'218GpP'!'KKP'-2GK2GI'U8G>'*'J5)*1':)9):)1J)'*1.'*'P>-:G'G8+) J-1PG*1G6'G>)'!'KKP'-2GK2G'G4K8J*554'G:*JHP'G>)'!'KKP'81K2G',8G>81'*'c!1P',81.-,I W>)'.)9*25G'G8+)%J-1PG*1G'-9'"I"T'>-2:P'8P'*KK:-K:8*G)'9-:'5-JH81L'G-'G>)'G4K8J*5'S=3':)J)80):I [-,)0):6'89'G>):)'8P'*':*K8.'J>*1L)'81'G>)'*+N8)1G'G)+K):*G2:)',>8J>'J*2P)P'G>)'=(3!$'GJ>*1L)'9:)V2)1J4'N4'!i!$%!!6'G>)'J>*1L)',855'1-G'N)'*KK:)J8*N54')99)JG).'N4'G>)'=\\'.2:81L G>)'98:PG'>-2:6'*1.'-1)',-25.')EK)JG'G-'P))'*'.:89G'N)G,))1'G>)'!'KKP'81K2G'*1.'G>)'!'KKP -2GK2G'-1'G>)'-:.):'-9'RX$$'i'!$%!!6'-:'RX'1PI W>)'D3B"T'81.8J*G)P'G>*G'8G'8P'P41J>:-18^).'G-'G>)'!'KKP'81K2G'N4'*'9:-1G'K*1)5'\]&'*1.'*':)*: K*1)5'*5*:+':)5*4I'W>)'218G',855'81.8J*G)'G>*G'8G'8P'P41J>:-18^).',>)1'G>)'!'KKP'81K2G'8P K:)P)1G'*1.'89'8G'-JJ2:P',8G>81'c!'`P'-9'G>)'!'KKP'-2GK2GI'@/'P81L5)'.:-KK).'K25P)'-1'G>)'!'KKP 81K2G',855'J*2P)'G>)'218G'G-'81.8J*G)'G>*G'8G'8P'1-G'P41J>:-18^).6'N2G'G>):)'8P'1-'.)G:8+)1G*5 )99)JG'9:-+'+8PP81L'*'P+*55'12+N):'-9'!'KKP'81K2GPIA OG'8P'V28G)'J-++-1'9-:'*'218G'G-'81.8J*G)'G>*G'8G'>*P'*JV28:).6'*1.'G>)1'5-PG6'P41J>:-18^*G8-1 .)K)1.81L'-1'G>)'818G8*5'9:)V2)1J4'-99P)G'N)G,))1'G>)'D3B"T'*1.'G>)'!'KKP':)9):)1J)I 32KK-P)'G>*G'*'D3B"T'8P'-2G'-9'J*58N:*G8-1'N4'!i!$%#'*1.'*'!'KKP'81K2G'8P'*KK58).',>85)'2P81L G>)'.)9*25G'=\\'G8+)'J-1PG*1G'-9'j=W -2:PI'U8G>'G>8P'G8+)%J-1PG*1G6'G>)'=\\ *5L-:8G>+'>*P'58GG5)')99)JG'-1'G>)'D3B"TpP'9:)V2)1J4'-9'-K):*G8-1'.2:81L'G>)'98:PG'>-2:'-9 K>*P)'5-JH81L6'*1.'G>)'!'KKP'-2GK2G',855'PG:*4'9:-+'G>)'!'KKP'81K2G'N4'*N-2G'RX$$'i'!$%#6'-: RIX'`PI'W>8P'8P'5*:L):'G>*1'G>)'c!'`P'P41J>:-18^*G8-1',81.-,6'*1.'P-'G>)'218G',855'81.8J*G) G>*G'8G'8P'1-G'P41J>:-18^).I'U8G>'G>)'.)9*25G'G8+)'J-1PG*1G6'G>)'218G',855'K255'8GP'!'KKP'-2GK2G'G,8G>81'G>)'c!'`P'P41J>:-18^*G8-1',81.-,',8G>81'*'9),'>-2:P6'*1.',855'G>):)*9G):'81.8J*G)'G>*G 8G'8P'K:-K):54'P41J>:-18^).I FS725 Rubidium Frequency Standard Operation 13 W>)'G*N5)'N)5-,'P>-,P'G>)'=\\'K*:*+)G):P'9-:'G>)'*55-,).'0*52)P'-9'G>)'=W'K*:*+)G):I'W>) :8L>G%+-PG'J-52+16'ju*G2:*5'W8+)'7-1PG*1Gk6'8P'G>)'N)PG'+)*P2:)'-9'G>)'=\\':)PK-1P) J>*:*JG):8PG8JPI'@W>)'0*52)P'P>-,1'*:)'9-:'G>)'.)9*25G'PG*N858G4'K*:*+)G):6'yz!IA PT Parameter Integrator TimeConstant Integral Gain Proportional Gain Natural TimeConstant Parameter set by PT command (hours) (SF bits per hour per ns of time-tag) (SF bits per ns of time-tag) Characterizes PLL response (hours) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 0.07 0.14 0.28 0.57 1.14 2.28 4.55 9.10 18.20 36.41 72.82 145.64 291.27 582.54 1,165.08 -14.063 -7.031 -3.516 -1.758 -0.879 -0.439 -0.220 -0.110 -0.055 -0.027 -0.014 -0.007 -0.003 -0.002 -0.001 -3.95 -2.80 -1.98 -1.40 -0.99 -0.70 -0.49 -0.35 -0.25 -0.17 -0.12 -0.09 -0.06 -0.04 -0.03 0.14 0.20 0.28 0.40 0.56 0.80 1.12 1.59 2.25 3.18 4.50 6.36 8.99 12.72 17.99 D2:G>):'.)G*85P'-9'G>)'K>*P)%5-JH81L'*5L-:8G>+'*:)'K:-08.).'81'G>)'=(3!$'(2N8.82+ D:)V2)1J4'3G*1.*:.'+*12*5I FS725 Rubidium Frequency Standard 14 Monitoring and Control Monitoring and Control via the RS-232 /'U81.-,Pm'N*P).'K:-L:*+6'(NZ-16'8P'K:-08.).'-1'*'R{k'95-KK4'.8PJI'W>)'K:-L:*+'+*4 *5P-'N)'.-,15-*.).'9:-+'G>)'3(3',)N'P8G)'*G',,,IG>81H3(3IJ-+I''W>)'K:-L:*+'9*J858G*G)P +-18G-:81L6'J-1G:-56'*1.'J*58N:*G8-1'-9'G>)'D3B"T'(2N8.82+'D:)V2)1J4'3G*1.*:.'08*'G>) J-+K2G):pP'7QZ'K-:G'-0):'*'P):8*5'(3%"R"'81G):9*J)I (21181L'G>)'O1PG*55'K:-L:*+',855'K5*J)'G>)'(NZ-1'8J-1'-1'G>)'&)PHG-K'*1.'81'G>)'3G*:G =:-L:*+P'58PG'*1.'K5*J)'G>)'K:-L:*+'J-+K-1)1GP'81'G>)'9-5.):'j(NZ-1kI'W>)'@K:-08.).A a181PG*55'2G858G4'P>-25.'N)'2P).'G-':)+-0)'G>)'K:-L:*+'*1.'8GP'8J-1P'9:-+'4-2:'J-+K2G):I 34PG)+':)V28:)+)1GP'81J52.)'|!T$Z[^'=)1G82+'-:'J-+K*:*N5)6'U81.-,Pm'#T'-:'5*G):6'*1. *1'*0*85*N5)'7QZ'K-:GI W>)'.)9*25G'7QZ'K-:G'8P'7QZ!I'O9'4-2:'J-+K2G):'2P)P'7QZ!'*P'*'+-2P)'K-:G6'4-2',855 1)).'G-'J>*1L)'G>)'7QZ'K-:G'G-'7QZ"I W>)'D3B"T'2P)P'G>)'=(3!$':2N8.82+'9:)V2)1J4'PG*1.*:.6'*5P-'+*129*JG2:).'N4'3G*19-:. ()P)*:J>'34PG)+PI'/55'J-++*1.P'P)1G'G-'G>)'D3B"T'*:)'K*PP).'.8:)JG54'G-'G>)'=(3!$I'/55 J-++*1.P':)J)80).'9:-+'G>)'D3B"T'J-+)'.8:)JG54'9:-+'G>)'=(3!$I'u-'N299):81L'-:'985G):81L -9'J-++*1.P'8P'K):9-:+).'N4'G>)'D3B"TI'W>)'=(3!$'-K):*G8-1'*1.'P):08J)'+*12*56',>8J>'8P *1'*..)1.2+'G-'G>8P'.-J2+)1G6'P):0)P'*P'*'K:-L:*++81L':)9):)1J)'9-:'G>)'D3B"TI Setting up Communications W>)'=(3!$'9:)V2)1J4'PG*1.*:.'J*1'J-++218J*G)'-K):*G81L'*1.'J*58N:*G8-1'P)GG81LP6'P2J>'*P 5-JH'81.8J*G-:P6'P8L1*5'5)0)5P6'>)*G):'J-1G:-5'PG*G2P6'!'KKP'G8+)'G*LP6'PG*G2P'95*LP6'*1. J*58N:*G8-1'K*:*+)G):PI'W>8P'K:-08.)P'G>)'P4PG)+Pp'81G)L:*G-:',8G>'G>)'*N858G4'G-'+-18G-:'*1. J-1G:-5'G>)'-K):*G8-1'-9'G>)'=(3!$I 7-++218J*G81L',8G>'G>)'=(3!$'8P'1-G':)V28:).'81'+-PG'*KK58J*G8-1PI'W>)'=(3!$'J-+)P'9:-+ G>)'9*JG-:4'J*58N:*G).'G-'cTi!$%!!6'*1.'G>)'D3B"T'K:-08.)P'9:-1G'K*1)5'\]&P'G-'81.8J*G) K-,):6'5-JH6'*1.'!'KKP'P41J>:-18^*G8-1I }-2'+*4',*1G'G-'J-++218J*G)',8G>'G>)'=(3!$'G-'*JJ)PP'*.0*1J).'9)*G2:)P'-:'9-:')0*52*G8-1 -9'G>)'=(3!$'81'*1'Q]Z'*KK58J*G8-1I'D-:'81PG*1J)6',>)1'5-JH81L'G>)'=(3!$'G-'*1')EG):1*5'! KKP':)9):)1J)'4-2'+*4',*1G'G-'-KG8+8^)'G>)'G8+)'J-1PG*1G'*1.'5-JH'+-.)'-9'G>)'.8L8G*5'=\\ G-'+*GJ>'G>)'PG*N858G4'J>*:*JG):8PG8JP'-9'4-2:':)9):)1J)I Getting Connected W>)'=(3!$'2P)P'G>)'(3%"R"'K:-G-J-5'9-:'J-++218J*G8-1I'Z-PG'J-+K2G):P'>*0)'-1)'-:'+-:) J-++218J*G8-1P'K-:GP'9-:'G>8P'K2:K-P)I'W-')PG*N58P>'J-++218J*G8-1',8G>'G>)'=(3!$'4-2',855 1)).'*'PG*1.*:.6'PG:*8L>G%G>:-2L>'#%K81'(3%"R"'J*N5)'J-11)JG).'N)G,))1'4-2:'J-+K2G):pP J-++218J*G8-1P'K-:G'*1.'G>)'&f#'J-11)JG-:'-1'G>)'N*JH'-9'G>)'D3B"TI Q1J)'G>)'J*N5)'8P'81'K5*J)6'4-2'1)).'G-'G)55'G>)'P-9G,*:)',>8J>'7QZ'K-:G'4-2',855'N)'2P81L'GJ-++218J*G)',8G>'G>)'D3B"TI'W>8P'8P'.-1)',8G>'G>)'K255'.-,1'58PG'N-E'5-J*G).'81'G>)'2KK): FS725 Rubidium Frequency Standard Monitoring and Control 15 :8L>G'K-:G8-1'-9'G>)'+*81',81.-,I'aP)'G>)'K255'.-,1'58PG'N-E'G-'P)5)JG'G>)'7QZ'K-:GI'D-: +-PG'J-+K2G):P'G>8P',855'N)')8G>):'7QZ!'-:'7QZ"I'Z*H)'P2:)'G>*G'G>)'j7-11)JG).k'N-E'8P J>)JH).I'W>8P',855'*JG80*G)'G>)'J-++218J*G8-1P'K-:GI Testing the Connection W)PG'G>)'J-11)JG8-1'N4'P)1.81L'*'J-++*1.'G-'G>)'=(3!$'G-'P))'G>*G'8G':)PK-1.P'K:-K):54I W4K)'G>)'J-++*1.'O&~'*1.'K:)PP'g]uW](hI'W>)'=(3!$'P>-25.':)PK-1.',8G>'8GP'8.)1G898): PG:81LI'/'G4K8J*5'PJ:))1'P>-G',8G>'*55'G>)'K):G81)1G')5)+)1GP'K-81G).'-2G'8P'P>-,1'N)5-,I RS-232 Communications aP)'G>)'G*N'5*N)5).'(3%"R"'7-++218J*G8-1P'G-'P)1.'J-++*1.P'G-'G>)'=(3!$'+*12*554I'W>8P G*N'8P'+)*1G'G-'K:-08.)'G>)'2P):',8G>'*1')*P4'+)G>-.'9-:'+*12*554'G4K81L'J-++*1.P'G-'G>) =(3!$I'W-'2P)'8G6'+*H)'P2:)'G>*G'G>)'K:-K):'J-++218J*G8-1P'K-:G'8P'P)5)JG).6'*1.'G>*G'G>) j7-11)JG).k'N-E'8P'J>)JH).I'Q1J)'G>*G'8P'J-+K5)G)6'P)1.81L'*'J-++*1.'G-'G>)'=(3!$'8P'*P P8+K5)'*P'G4K81L'8G'81'*1.'K:)PP81L'g]uW](hI D-:')*P)'-9'81G):K:)G*G8-16'J-++*1.P'G>*G'4-2'G4K)',855'N)'9-:+*GG).'81'boldI'()PK-1P)P 9:-+'G>)'=(3!$',855'>*0)'1-:+*5'9-:+*GG81LI't))K'81'+81.'G>*G'G>)'=(3!$',855'1-G':)PK-1. G-'*55'J-++*1.PI'OG'-154':)PK-1.P'G-'V2):4'J-++*1.P•-1)P')1.81L',8G>'*'V2)PG8-1 +*:H'@~AI Q1)'8+K-:G*1G'K-81G'G-'H))K'81'+81.'8P'G>*G'J-++*1.P'J*1'-154'N)')1G):).'-1'G>)'5*PG'581)I \81)P'*N-0)'G>)'5*PG'581)'P>-,'G>)'K:)08-2P'J-++*1.P'P)1G'*1.':)PK-1P)P':)J)80).I'W>)P) 581)P'J*1'1-G'N)'-0):,:8GG)1I'Q154'G>)'5*PG'581)'8P'*0*85*N5)'9-:'G4K81L'81'1),'J-++*1.PI FS725 Rubidium Frequency Standard 16 Monitoring and Control [):)'8P'*'P*+K5)'PJ:))1'P>-G'K-81G81L'-2G'G>)'K):G81)1G'8G)+P'-9'81G):)PGI Rb Stats W>)'G*N'5*N)5).'(N'3G*GP'8P'2P).'G-'+-18G-:'08:G2*554'*55'-9'G>)'=(3!$pP'P)GG81LPI'W-'08),'G>) J2::)1G'=(3!$'P)GG81LP6'J58JH'-1'G>)'(N'3G*GP'G*N6'+*H)'P2:)'G>*G'G>)'P)5)JG). J-++218J*G8-1P'K-:G'8P'J-::)JG6'*1.'J58JH'G>)'j7-11)JG).k'J>)JH'N-E'G-')1*N5)'G>) J-11)JG8-1I'W>)'PJ:))1'P>-25.'9855'81',8G>'G>)'J2::)1G'=(3!$'P)GG81LPI'W>)'P)GG81LP',855'N) J-1G812-2P54'2K.*G).'21G85'4-2'.8PJ-11)JG'9:-+'G>)'J-++218J*G8-1P'K-:G'N4'J58JH81L'-1'G>) j7-11)JG).k'J>)JH'N-E'*'P)J-1.'G8+)'G-'21J>)JH'8GI FS725 Rubidium Frequency Standard Monitoring and Control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actory Settings W>8P'P)JG8-1'81J52.)P'J*58N:*G8-1'0*52)P'*1.'K*:*+)G):P'9-:'J-1G:-5581L'G>)'9:)V2)1J4'-9'G>) =(3!$I'W>)'+-PG'8+K-:G*1G'K*:*+)G):'>):)'8P'j\Qk6',>8J>'81.8J*G)P',>)G>):'G>)'=(3!$'>*P 5-JH).'G-'G>)'(N'*G-+8J'>4K):981)'G:*1P8G8-1I'O1'G>)'PJ:))1'P>-G6'G>)'0*52)'-9'\Q'8P'^):-6 81.8J*G81L'G>*G'G>)'218G'>*P'1-G'4)G'5-JH).'G-'G>)'*G-+8J'G:*1P8G8-1I'OG'8P'>8L>58L>G).',8G>'* N52)'N-E'G-'81.8J*G)'G>*G'G>8P'0*52)'8P'5-,):'G>*1'1-:+*5I FS725 Rubidium Frequency Standard 18 Monitoring and Control Analog Output Values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pps Control W>8P'P)JG8-1'J-1G*81P'J*58N:*G8-1'K*:*+)G):P'G>*G'J-1G:-5'G>)'=(3!$pP'N)>*08-:',>)1'5-JH81L G-'*1')EG):1*5'!'KKP':)9):)1J)I'O1'G>)')E*+K5)'PJ:))1'P>-G6'=W'8P'>8L>58L>G).',8G>'*'N5*JH'N-EI W>8P'8P'+)*1G'G-'81.8J*G)'G>*G'8GP'J2::)1G'0*52)6'!;6'8P'.899):)1G'9:-+'G>)'0*52)'PG-:).'81 ]]=(QZ6',>8J>'8P'G>)'0*52)'8G',855'>*0)'*G'PG*:G'2KI'O1'G>8P'K*:G8J25*:'J*P)6'G>)'J-++*1. =W!;',*P')1G):).'+*12*554'81'G>)'(3%"R"'7-++218J*G8-1P'G*N'G-'J>*1L)'G>)'J2::)1G'0*52) -9'=W'9:-+'<'G-'!;I'W>)'0*52)'9-:'WW6'G>)'5*PG'0*58.'G8+)'G*L6'8P'N5*1H'N)J*2P)'G>)'218G'>*P'1-G 4)G':)J)80).'*'K25P)'-1'8GP'!'KKP'81K2GI'U>)1'*'K25P)'8P':)J)80).6'G>)'WW'J-++*1.',855':)K-:G G>)'G8+)'.899):)1J)'81'1*1-P)J-1.P'N)G,))1'G>)'81K2G'K25P)'*1.'G>)'!'KKP'-2GK2GI Colored Boxes W>)'J-5-:).'N-E)P'*:)'08P2*5'J2)P'G-'5)G'G>)'2P):'H1-,'G>*G'*'L80)1'K*:*+)G):'8P'-2GP8.)'G>) 1-:+*5'-K):*G81L':*1L)I'W>8P'+-PG'J-++-154'-JJ2:P'*G'PG*:G'2K6',>85)'G>)'218G'8P',*:+81L 2KI'/9G):'*N-2G'!T'+812G)P'-9'-K):*G8-16'G>)'218G'P>-25.'N)'92554',*:+).'2K6'*1.'*55':).'*1. N52)'N-E)P'P>-25.'.8P*KK)*:I'/9G):'G>)'818G8*5',*:+2K6'G>)'*KK)*:*1J)'-9'*'J-5-:).'N-E G4K8J*554'P8L1*5P'P-+)G>81L'212P2*5'G>*G'P>-25.'N)'5--H).'81G-I'O9'G>)'218G',*P'N)81L'-K):*G). 81'*1'-0)16'9-:')E*+K5)6'G>)'218G'+*4'1-G'N)'*N5)'G-'K:-K):54':)L25*G)'G>)'G)+K):*G2:)P'-9'G>) J:4PG*56'J)556'*1.'5*+KI'a1.):'G>)P)'J8:J2+PG*1J)P6'-1)',-25.')EK)JG'N52)'N-E)P'G-'*KK)*: 1)EG'G-'/&T6'/&X6'*1.'/&B6'*P'G>)'>)*G):P'*:)'P>2G'-99I W>)'81G):K:)G*G8-1'-9'G>)'N-E)P'8P'*P'9-55-,P? '@().A'Y*52)'8P'>8L>):'G>*1'1-:+*5I '@f52)A'Y*52)'8P'5-,):'G>*1'1-:+*5I '@f5*JHAY*52)'8P'.899):)1G'9:-+'G>)'0*52)'PG-:).'81']]=(QZ FS725 Rubidium Frequency Standard Monitoring and Control 19 File Menu Print W>)'K:-L:*+'J*1'K:81G'-2G'G>)'J2::)1G'P)GG81LP'P>-,1'81'G>)'(N'3G*GP'G*NI'W-'.-'G>8P6'+*H) P2:)'G>*G'G>)'(N'3G*GP'G*N'8P'08P8N5)'*1.'G>)1'P)5)JG'=:81G'9:-+'G>)'D85)'+)12I'W>)'J2::)1G 0*52)P'.8PK5*4).'81'(N'3G*GP',855'N)'P)1G'G-'G>)'K:81G):I'W>)'9-:+*GG81L'-9'G>)'K:81G).'-2GK2G'8P 81G)1.).'9-:'PG*1.*:.'<'{'N4'!!'81J>6'\)GG):'P8^)'K*K):I'=:81G81L'-1'K*K):'-9'-G>):'P8^)P'8P'1-G P2KK-:G).6'N2G'1-G'K:)0)1G).I Print Setup =:81G'3)G2K')1*N5)P'4-2'G-'J-198L2:)'4-2:'K:81G):'9-:'K:81G81LI'}-2'P>-25.'J>--P)'\)GG):'P8^) K*K):'@<'{'N4'!!'81J>A'*1.'G>)'=-:G:*8G'-:8)1G*G8-1I'\*1.PJ*K)'-:8)1G*G8-1'8P'1-G'P2KK-:G).I Exit W>)']E8G'+)12'8G)+',855'J5-P)'G>)'K:-L:*+I Help Menu Contents 7>--P)'G>8P'+)12'8G)+'G-'.8PK5*4'>)5K'819:-+*G8-1I About 7>--P)'G>8P'+)12'8G)+'G-'.8PK5*4'G>)'K:-L:*+'1*+)'*1.'0):P8-1'819-:+*G8-1I Communicating with Other Devices (NZ-1',*P'.)P8L1).'G-'J-++218J*G)',8G>'G>)'=(3!$6'>-,)0):'+*14'K)-K5)'>*0)'2P).'G>) (3%"R"'7-++218J*G8-1P'G*N'*P'*'L)1):*5'K2:K-P)'.2+N'G):+81*5'9-:'J-++218J*G81L',8G> -G>):'81PG:2+)1GP'*1.'.)08J)PI'O9'4-2',8P>'G-'.-'G>8P6'H))K'81'+81.'G>)'9-55-,81L'G)J>18J*5 58+8G*G8-1P? • W>)'J-++218J*G8-1P'K-:G'J-198L2:*G8-1'8P'98E).'*G'#X$$'N*2.6'<'N8GP'K):'N4G)6'1-'K*:8G46 *1.'!'PG-K'N8GI • /'J*::8*L)':)G2:16'g7(h6'8P'*KK)1.).'G-')*J>'J-++*1.'P)1GI • 7-++*1.P'*:)'P)1G'-1'*'581)'N4'581)'N*P8PI'u-G>81L'8P'P)1G'21G85'G>)'2P):'>8GP'G>) g]uW](h'H)46'*9G):',>8J>'G>)')1G8:)'581)'8P'P)1G',8G>'*'g7(h'*KK)1.).'G-'G>)')1.I • ()PK-1P)P'G-'J-++*1.P'9:-+'G>)'.)08J)'*:)')EK)JG).'G-'N)'G):+81*G).'N4'*'J*::8*L) :)G2:16'g7(hI • a1K:81G*N5)'J>*:*JG):P',855'1-G'N)'.8PK5*4). • W>)'K:-L:*+'.-)P'1-G'K:-08.)'*14'9*J858G4'9-:'J2PG-+8^81L'G>)'7QZ'K-:G'P)GG81LP'9-: J-++218J*G8-1',8G>'-G>):'.)08J)PI FS725 Rubidium Frequency Standard 20 Calibration Calibration W>):)'8P'*'!T%G2:1'K-G)1G8-+)G):'81'G>)'=(3!$':2N8.82+'9:)V2)1J4'PG*1.*:.',>8J>'*.l2PGP'G>) -K):*G81L'9:)V2)1J4I'W>)'K-G)1G8-+)G):'8P'*JJ)PP8N5)'N)1)*G>'*'J*58N:*G8-1'PG8JH):'-1'G>)'5)9G P8.)'-9'G>)'81PG:2+)1GI'W>)'G-G*5'*.l2PG+)1G':*1L)'2P81L'G>)'K-G)1G8-+)G):'8P'c$I$$"'KK+'-: c$I$"'[^'*G'!$'Z[^I'W2:181L'G>)'K-G)1G8-+)G):'J5-JH,8P)',855'81J:)*P)'G>)'!$'Z[^'-2GK2G N4'*N-2G'$I$$"T'[^'K):'G2:1I W>)'K-P8G8-1'-9'G>)'K-G)1G8-+)G):'+*4'N)'.)G):+81).'N4'+)*P2:81L'G>)'.J'0-5G*L)'-1'G>) J)1G):'K81'-9'G>)':)*:'K*1)5'D(]v'/&w'fu7I'W>)'0-5G*L)',855':)*.'$'Y&7'*G'G>)'J-21G):% J5-JH,8P)')EG:)+)6'eT'Y&7'*G'G>)'J5-JH,8P)')EG:)+)6'*1.'e"IT$'Y&7',>)1'G>) K-G)1G8-+)G):'8P'J)1G):).I'W>8P'0-5G*L)'P>-25.'N)':)J-:.).'N)9-:)'*14'J*58N:*G8-1'8P *GG)+KG).I'W>8P',855'*55-,'4-2'G-':)G2:1'G-'G>)'K:)08-2P'J*58N:*G8-1'89'1)J)PP*:4'*1.'P):0)P'*P *':)J-:.'-9'G>)'9:)V2)1J4'*L81L'-9'G>)'218GI U>)1'G>)'D3B"T'8P'P>8KK).'9:-+'G>)'9*JG-:46'G>)'K-G)1G8-+)G):'8P'P)G'G-'8GP'J)1G):'K-P8G8-1 *1.'G>)'9:)V2)1J4'8P'J*58N:*G).'08*'G>)'(3%"R"I'W>)'2P):'J*1':)G2:1'G>)'K-G)1G8-+)G):'G-'G>) J)1G):'K-P8G8-1'N4'*.l2PG81L'G>)'K-G)1G8-+)G):'21G85'G>)'.J'0-5G*L)'-1'G>)'J)1G):'K81'-9'G>) :)*:'K*1)5'D(]v'/&w'fu7'+)*P2:)P'e"IT$Y&7I W>)'K:-J).2:)'8P'G-'*.l2PG'G>)'J*58N:*G8-1'K-G)1G8-+)G):'P-'G>*G'G>)'D3B"T'K:-.2J)P'!$'Z[^ G-',8G>81'c!'i'!$%!!'-:'!$'Z[^'c'$I$$$![^I'O+K-:G*1G'.)G*85P'*:)'58PG'N)5-,? !I f)'J):G*81'G>*G'G>)'D3B"T'>*P'N))1'-K):*G).'J-1G812-2P54'9-:'*G'5)*PG'";'>-2:PI "I O9'G>)'D3B"T'>*P'N))1'-99'9-:'+-:)'G>*1'-1)',))H6'8G'P>-25.'N)'-K):*G).'J-1G812-2P54'9-: *G'5)*PG'B"'>-2:P'N)9-:)'G>)'*.l2PG+)1G'8P'+*.)I RI f)'J):G*81'G>*G'1-G>81L'8P'J-11)JG).'G-'G>)':)*:%K*1)5'D(]v'/&w'81K2GI ;I f)'J):G*81'G>*G'1-G>81L'8P'J-11)JG).'G-'G>)':)*:%K*1)5'!'KKP'81K2GI TI Z)*P2:)'*1.':)J-:.'G>)'.J'0-5G*L)'-1'G>)'J)1G):'K81'-9'G>)'D(]v'/&w'fu7I XI =-,):'J4J5)'G>)'D3B"T'N4'21K52LL81L'8G'9-:'*G'5)*PG'G>:))'P)J-1.PI'W>8P',855'+*H)'J):G*81 G>*G'G>)'218G',855'G:*JH'G>)'J*58N:*G8-1'K-G)1G8-+)G):'@,>8J>'J*1'N)'8L1-:).'89'G>)'218G',*P K>*P)%5-JH).'G-'*'!'KKP'81K2G'-:'G>)'9:)V2)1J4'>*.'N))1'K:)08-2P54'P)G'08*'G>)'3D J-++*1.IA'W>)'218G'P>-25.'5-JH'81'5)PP'G>*1'*'+812G)'*P'8G'8P',*:+'9:-+'K:)08-2P -K):*G8-1I'U*8G'9-:'*G'5)*PG'-1)'>-2:'N)9-:)'K:-J)).81L',8G>'G>)'J*58N:*G8-1I BI W>)'9:)V2)1J4'PG*1.*:.'2P).'81'G>)'J*58N:*G8-1'+2PG'>*0)'*1'*JJ2:*J4'-9'N)GG):'G>*1'c!'i !$%!!'-:'!$'Z[^'c'$I$$$!'[^I'/'J)P82+'PG*1.*:.'-:'*',)55'J>*:*JG):8^).':2N8.82+'-: V2*:G^'PG*1.*:.':)9):)1J).'G-'S=3'+*4'N)'2P).I )'9:)V2)1J4'J-21G):'+2PG'>*0)'P2998J8)1G':)P-52G8-1'*1.'*JJ2:*J4'G-'K):9-:+'G>) +)*P2:)+)1GI'W>8P'+*4':)V28:)'5-1L'L*G)'G8+)P'81'G>)'9:)V2)1J4'+)*P2:)+)1G'+-.)'-9 -K):*G8-1I'/'!$$P'L*G)'8P':)J-++)1.).',>)1'2P81L'*1'3(X"$'W8+)'O1G):0*5'7-21G):'81 G>)'9:)V2)1J4'+-.)I #I aP2*5546'G>)'+)*P2:)+)1G'J*1'N)'.-1)'+-:)'V28JH54'*1.'*JJ2:*G)54'N4'J-+K*:81L'G>) K>*P)'-9'*'!$'Z[^':)9):)1J)'G-'G>)'K>*P)'-9'G>)'D3B"T'!$'Z[^'-2GK2GI'/'G8+)%81G):0*5 J-21G):'+*4'N)'2P).'9-:'G>8P'K2:K-P)I'O1'G>8P'J*P)6'G>)'!$'Z[^':)9):)1J)'8P'2P).'*P'* G8+)N*P)'9-:'G>)'G8+)%81G):0*5'J-21G):I'W>)'81K2GP'G-'G>)'G8+)%81G):0*5'J-21G):',855'N)'G,!$'Z[^'P8L1*5Pq'-1)'9:-+'G>)'!$'Z[^':)9):)1J)'*1.'-1)'9:-+'G>)'D3B"TI'W>)'G8+)% FS725 Rubidium Frequency Standard Calibration 21 81G):0*5'J-21G):'P>-25.'N)'P)G%2K'G-':)K-:G'G>)'*0):*L)'-9'!$$$'+)*P2:)+)1GPI'W>) :)K-:G).'G8+)%81G):0*5'+)*P2:)+)1GP',855'N)'N)G,))1'$'*1.'!$$'1P'@G>)'K):8-.'-9'*'!$ Z[^'P8L1*5IA'aP81L'G>)'3(X"$6'G>)':)P-52G8-1'*1.'l8GG):'-9'G>)'*0):*L)'-9'!$$$'G8+)% 81G):0*5'+)*P2:)+)1GP',855'N)'5)PP'G>*1'!'KP':+P6'*1.'0*52)P',855'N)':)K-:G).'*N-2G'-1J) *'P)J-1.I'QNP):0)'>-,'G>)'*0):*L)'G8+)%81G):0*5'+)*P2:)+)1G'J>*1L)P',8G>'G8+)I'O9'G>) :)K-:G).'G8+)%81G):0*5P'*:)'J>*1L81L'N4'!1P'K):'P)J-1.'G>)1'G>)'G,-'!$'Z[^'P-2:J)'*:) j-99k'N4'!'i'!$%#'-:'$I$$!'KK+I'/.l2PG'G>)'J*58N:*G8-1'K-G)1G8-+)G):'21G85'G>)'.:89G N)G,))1'G8+)%81G):0*5'+)*P2:)+)1GP'P5-,P'G-'5)PP'G>*1'!'i'!$%!!'-:'!$'KP'K):'P)J-1.I !$I Z)*P2:)'*1.':)J-:.'G>)'.J'0-5G*L)'-1'G>)'J)1G):'K81'-9'G>)'D(]v'/&w'fu7I FS725 Rubidium Frequency Standard 22 Calibration Calibration using a 1 pps signal (such as from a GPS receiver) W>)'D3B"T'+*4'*5P-'N)'J*58N:*G).'N4'K>*P)%5-JH81L'G>)'218G'G-'G>)'!'KKP'P8L1*5'9:-+'*'S=3 :)J)80):I'W>)'J*58N:*G8-1'K-G)1G8-+)G):',855'N)'*.l2PG).'P-'G>*G'G>)'9:)V2)1J4'J-1G:-5 K*:*+)G):6'3D6'+*GJ>)P'G>)'0*52)'.)G):+81).'N4'G>)'K>*P)%5-JH81L'*5L-:8G>+I U>)1'*'K:)J8P)'!'KKP'P8L1*5'8P'*KK58).'G-'G>)'!'KKP'81K2G'-1'G>)':)*:'K*1)5'-9'G>)'D3B"T6'G>) :2N8.82+'9:)V2)1J4'PG*1.*:.',855'K>*P)%5-JH'G-'G>)'P8L1*5I'W>)'!'KKP'P8L1*5'2P2*554'J-+)P 9:-+'*'S=3':)J)80):',>8J>'J*1'>*0)'*'5-1L%G):+'*JJ2:*J4'-9'*'9),'K*:GP'81'!$!"I'f)J*2P)'G>) PG*N858G4'-9'G>)'!'KKP':)9):)1J)'81'G>)'P>-:G'G):+'J*1'N)'+2J>',-:P)'G>*1'G>*G'-9'G>)'=(3!$6 G>)'=(3!$'K>*P)%5-JHP'G-'G>)'!'KKP',8G>'*'0):4'5-1L'G8+)'J-1PG*1G'-9'P)0):*5'>-2:P'-:'+-:)I /'J5*PP8J*5'"1.'-:.):'K>*P)%5-JH'J-1G:-5'5--K'8P'8+K5)+)1G).'81'98:+,*:)I'W>)'jK>*P) J-+K*:*G-:k'8P'*'G8+)%G*LL81L'J8:J28G',>8J>'+)*P2:)P'G>)'G8+81L'-9'G>)'!'KKP'81K2G',8G> 1*1-P)J-1.':)P-52G8-1I'/'K:-K-:G8-1*5%81G)L:*5'K>*P)%5-JH'*5L-:8G>+'J-1G:-5P'G>)'9:)V2)1J4 -9'G>)':2N8.82+'9:)V2)1J4'PG*1.*:.',8G>'G>)'3D'K*:*+)G):'@3)G'D:)V2)1J4AI'u-:+*5546'G>)'3D K*:*+)G):'8P'P)G'N4'G>)'98:+,*:)':)*.81L'G>)'J*58N:*G8-1'K-G)1G8-+)G):I'[-,)0):6',>)1'*'! KKP'P8L1*5'8P'P))16'G>)'K>*P)%5-JH'*5L-:8G>+'x>8l*JHPp'G>)'3D'K*:*+)G):'G-'K>*P)%5-JH'G>) :2N8.82+'9:)V2)1J4'PG*1.*:.'G-'G>)'!'KKP'81K2GI W-'J*58N:*G)',8G>'*'K:)J8P)'!'KKP'81K2G6'G>)'D3B"T',855'N)'K>*P)%5-JH).'G-'G>)'!'KKP'81K2G'*1. G>)'3D'K*:*+)G):',855'N)':)*.'08*'G>)'(3%"R"'81G):9*J)I'W>)16'G>)'!'KKP'81K2G',855'N) :)+-0).6'G>)'218G',855'N)'K-,):'J4J5).'@P-'G>*G'G>)'3D'8P'*L*81'P)G'N4'G>)'J*58N:*G8-1 K-G)1G8-+)G):A6'*1.'G>)'K-G)1G8-+)G):',855'N)'*.l2PG).'G-'K:-08.)'G>)'P*+)'3D'0*52)'*P',*P P))1',>)1'G>)'D3B"T',*P'K>*P)'5-JH).'G-'G>)'!'KKPI W-'2P)'G>8P'K:-J).2:)'4-2',855'1)).'*'P-2:J)'-9'*'K:)J8P)'!'KKP'P8L1*56'P2J>'*P'*'S=3'G8+81L :)J)80):I'}-2',855'*5P-'1)).'*',*4'G-'J-++218J*G)',8G>'G>)'D3B"T'08*'G>)'(3%"R"6'P2J>'*P'* =7'-:'5*KG-K'J-+K2G):',8G>'*'P):8*5'K-:G'-K):*G81L'*G'#X$$'N*2.I'/14'U81.-,P'J-+K2G): G-L)G>):',8G>'G>)'D3B"T'*KK58J*G8-1'K:-L:*+6'(NZ-16',855',-:H',)55I FS725 Rubidium Frequency Standard Calibration 23 Procedure for frequency calibration using a precise 1 pps input ! " R ; T X B < # !$ !! !" !R f)'J):G*81'G>*G'1-G>81L'8P'J-11)JG).'G-'G>)':)*:%K*1)5'D(]v'/&w'81K2GI f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v'/&w'fu7I'W>)'0-5G*L)',855':)*.'$Y'*G G>)'J-21G):%J5-JH,8P)')EG:)+)'-:'eT'Y&7'*G'G>)'J5-JH,8P)')EG:)+)'*1.',855':)*. e"IT$Y&7',>)1'G>)'K-G)1G8-+)G):'8P'J)1G):).I'W>8P'0-5G*L)'P>-25.'N)':)J-:.).'N)9-:) *14'J*58N:*G8-1'8P'*GG)+KG).I'W>8P',855'*55-,'4-2'G-':)G2:1'G-'G>)'K:)08-2P'J*58N:*G8-1'89 1)J)PP*:4'*1.'P):0)P'*P'*':)J-:.'-9'G>)'9:)V2)1J4'*L81L'-9'G>)'218GI 7-11)JG'G>)'(3%"R"'P):8*5'J*N5)'N)G,))1'G>)'D3B"T'*1.'G>)'=7'-:'5*KG-K'J-+K2G):'*1. 0):894'G>*G'4-2'J*1'jG*5Hk'G-'G>)'D3B"TI f)'J):G*81'G>*G'G>)'D3B"T'>*P'N))1'-K):*G).'J-1G812-2P54'9-:'*G'5)*PG'";'>-2:P'@)EJ52.81L G>)'N:8)9'K-,):%J4J581LIA 3)1.'G>)'J-++*1.?'LM1I'W>8P')1*N5)P'G>)'!'KKP'81K2G'.8L8G*5'K:)%985G):'G-':).2J)'G>) 1-8P)'-9'G>)'!'KKP':)9):)1J)I'@\Z!'8P'G>)'.)9*25G'0*52)IA 3)1.'G>)'J-++*1.?'PT8I'W>8P'P)GP'G>)'x1*G2:*5'G8+)%J-1PG*1Gp'-9'G>)'=\\'G-'*N-2G'"I"T >-2:P6',>8J>':).2J)P'G>)'1-8P)'-9'G>)'!'KKP':)9):)1J)'N4'*0):*L81LI'@=W<'8P'G>)'.)9*25G 0*52)IA O9'G>)'D3B"T'>*P'N))1'-99'9-:'+-:)'G>*1'-1)',))H6'8G'P>-25.'N)'-K):*G).'J-1G812-2P54'9-: *G'5)*PG'B"'>-2:P'N)9-:)'G>)'*.l2PG+)1G'8P'+*.)I /KK54'G>)'!'KKP'P8L1*5'G-'G>)':)*:'K*1)5'-9'G>)'D3B"TI'W>)'9:-1G'K*1)5'j!'KKP'81K2Gk'\]& P>-25.'N581H'*G'!'KKP6'*1.'G>)'j!'KKP'P41Jk'\]&'P>-25.'58L>G'81'*N-2G'T'+812G)PI W[]'D3B"T'3[Qa\&'f]'=[/3]%\Q7t]&'DQ('/W'\]/3W'";'[Qa(3'f]DQ(] =(Q7]&OuS'WQ'W[]'u]€W'3W]=I v2):4'G>)'3D'K*:*+)G):'08*'G>)'(3%"R"I'@SF?'W>)':)PK-1P)',855'N)'*'12+N):'N)G,))1 c"$$$AI'U:8G)'G>)'12+N):'.-,1I'W>)'3D'K*:*+)G):'8P'N)81L'J-1G:-55).'N4'G>)'K>*P)%5-JH 5--K'*5L-:8G>+'*1.'>*P'*':)P-52G8-1'-9'!?!$!"6'P-'c"$$$'J-::)PK-1.P'G-'c$I$$"KK+I'WP)G'G>)'D3B"T'G-'!?!$!!6'4-2',*1G'G-'.)G):+81)'G>)'J-::)JG'0*52)'-9'3D'G-'c!$6'P-'J>)JH N*JH'81'*'9),'>-2:P'G-'.)G):+81)'89'G>)'3D'K*:*+)G):'>*P'P)GG5).I'()K)*G'*P'1)J)PP*:4I U>)1'4-2'>*0)'*'P*G8P9*JG-:4'3D'0*52)6'21K52L'G>)'!'KKP'81K2G'*1.'K-,):'J4J5)'G>) D3B"T'G-':)G2:1'J-1G:-5'-9'G>)'3D'K*:*+)G):'G-'G>)'K-G)1G8-+)G):I'U>85)'+-18G-:81L'G>) 3D'K*:*+)G):'08*'G>)'(3%"R"6'*.l2PG'G>)'J*58N:*G8-1'K-G)1G8-+)G):'G-'P)G'G>)'3D'0*52)'GG>)'0*52)'P))1',>)1'G>)'218G',*P'K>*P)'5-JH).'G-'G>)'!'KKP':)9):)1J)I'u-,6')*J>'G8+)'G>) 218G'G2:1P'j-1k6'8G',855'N)'-K):*G81L'*G'G>)'P*+)'9:)V2)1J4'*P',>)1'8G'.8.',>)1'8G',*P K>*P)%5-JH).'G-'G>)'!'KKP':)9):)1J)I FS725 Rubidium Frequency Standard 24 Calibration Calibration of the time-tag offset parameter W>)'D3B"T'J*1'G8+)%G*L'G>)'5)*.81L').L)'-9'*':)*:%K*1)5'!'KKP'81K2GI'()P25GP'-9'G>)'G8+)%G*L *:)':)G2:1).'-0):'G>)'(3%"R"6'81':)PK-1P)'G-'G>)'WW~'J-++*1.6'81'81G)L):'1*1-P)J-1.P',8G> :)PK)JG'G-'G>)'!'KKP'-2GK2GI'O9'G>)'!'KKP'81K2G'*::80)P'T1P'*9G):'G>)'!'KKP'-2GK2G6'G>)'WW~ P>-25.':)G2:1'*'0*52)'-9'TI'O9'G>)'!'KKP'81K2G'*::80)P'T1P'N)9-:)'G>)'!'KKP'-2GK2G6'G>)'WW~ P>-25.':)G2:1'*'0*52)'-9'########TI'O9'1-'81K2G',*P'*KK58).6'*1.'P-'1-'G8+)%G*L':)P25G'8P *0*85*N5)6'G>)'WW~',855':)G2:1'*'0*52)'-9'%!I W>):)'8P'*'J*58N:*G8-1'K*:*+)G):6'jWQk6',>8J>'8P'*..).'G-'G>)'+)*P2:).'G8+)%G*L'N)9-:)'G>) :)P25G'8P':)G2:1).'-0):'G>)'(3%"R"I'Q99P)GP'81'G8+)%G*L':)P25GP'J*1'N)')58+81*G).'N4'*.l2PG81L G>)'WQ'K*:*+)G):I D),'2P):P',855'1)).'G-'K):9-:+'G>8P'J*58N:*G8-16'*P'98E).'-99P)GP'-9'*'9),'1*1-P)J-1.P'81'G>) :)K-:G).'G8+)%G*LP',855'>*0)'58GG5)'J-1P)V2)1J)I'32NPG*1G8*5'-99P)GP'*:)'2P2*554'J*2P).'N4'5-, -:'P5-,'K25P)P'K:-08.).'G-'G>)'!'KKP'81K2G?'W>)'!'KKP'81K2G'P>-25.'+*H)'*'J5)*1'G:*1P8G8-1 9:-+'$'G-'TY&7',8G>'*':8P)'G8+)'-9'5)PP'G>*1'!$1PI W-'J*58N:*G)'G>)'WQ'K*:*+)G):? !I "I RI ;I TI 7-11)JG'G-'G>)'D3B"TpP'P):8*5'K-:G'2P81L'G>)'(NZ-1'K:-L:*+I 3)5)JG'G>)'(3%"R"'7-++218J*G8-1P'G*NI Y):894'G>)'J-11)JG8-1'N4'G4K81L'G>)'O&~'J-++*1.I 3)1.'G>)'=\$'G-'.8P*N5)'K>*P)'5-JH81L'G-'G>)'!'KKP'81K2GI Y):894'G>*G'G>)'=\$'J-++*1.',*P':)J)80).'N4'G4K81L'G>)'=\~'J-++*1.6',>8J> P>-25.':)G2:1'*'j$k6'81.8J*G81L'G>*G'!'KKP'K>*P)'5-JH81L'8P'.8P*N5).I XI 7-11)JG'G>)'!'KKP'-2GK2G'.8:)JG54'G-'G>)'!'KKP'81K2G',8G>'*'Rp'(ST<'J-*E'J*N5)I'&1-G'2P)'*14'T$'b'G):+81*G-:PI BI v2):4'G>)'G8+)%G*L',8G>'G>)'WW~'J-++*1.I'O9'G>)':)P25G'8P'T1P6',>8J>'8P'G>)'G8+) .)5*4'-9'Rp'-9'(ST<'J-*E'J*N5)6'G>)1'4-2'*:)'.-1)I )':)P25G'-9'G>)'WW~'8P'1-G'T1P6'G>)1'V2):4'G>)'WQ'K*:*+)G):',8G>'*'WQ~'/'G4K8J*5 0*52)'-9'G>)'WQ'K*:*+)G):'8P'%!B$$1PI'W>8P'0*52)'8P'*..).'G-'G>)'G8+)%G*L +)*P2:)+)1G'N)9-:)'8P'8G':)G2:1).'08*'(3%"R"I #I O9'G>)':)P25G'-9'G>)'WW~',*P'L:)*G):'G>*1'T1P6'G>)1'81J:)*P)'G>)'+*L18G2.)'-9'G>)'WQ K*:*+)G):'@+*H81L'8G'+-:)'1)L*G80)IA'D-:')E*+K5)6'89'WW~':)G2:1).'!T1P6'*1.'WQ~ :)G2:1).'%!B$$6'G>)1'P)1.'WQ%!B!$I !$I O9'G>)':)P25G'-9'G>)'WW~'5)PP'L:)*G):'G>*1'T1P6'G>)1'.)J:)*P)'G>)'+*L18G2.)'-9'G>)'WQ K*:*+)G):'@+*H81L'8G'5)PP'1)L*G80)IA'D-:')E*+K5)6'89'WW~':)G2:1).'!1P6'*1.'WQ~ :)G2:1).'%!B$$6'G>)1'P)1.'WQ%!X#XI !!I OG):*G)'*P'1)J)PP*:46'*.l2PG81L'WQ6'21G85'G>)'WW~':)G2:1P'T1PI !"I 3*0)'G>)'WQ'K*:*+)G):'G-']]=(QZ'N4'P)1.81L'G>)'J-++*1.'WQ• !RI Y):894'G>*G'G>)'WQ',*P'P*0).'G-']]=(QZ'N4':)*.81L'8G'N*JH'9:-+']]=(QZ',8G> G>)'WQ•~'J-++*1.I FS725 Rubidium Frequency Standard Circuit Description 25 FS725 Circuit Description W>)'D3B"T'K:-08.)P'*1'-K):*G81L')108:-1+)1G'9-:'G>)'=(3!$'(2N8.82+'D:)V2)1J4'3G*1.*:.I W>)'=(3!$'-K):*G8-1'*1.'P):08J)'+*12*5'.)G*85P'-K):*G8-16'J8:J28GP6'*1.'P-9G,*:)'81G):9*J) 9-:'G>)':2N8.82+'9:)V2)1J4'PG*1.*:.'*P'*1'*..)1.2+'G-'G>8P'+*12*5I Rubidium Logic Interface (Sheet 1 of 2) w!$$'8P'G>)'J-11)JG-:'G-'G>)'=(3!$':2N8.82+'9:)V2)1J4'PG*1.*:.I'W>)'K81%-2G'9-:'w!$$'8P .)G*85).'81'G>)'G*N5)'N)5-,? Pin No. Name ! " R ; T X B < # !$ \Q7t_!'KKP'QaW =QW'UO=]( =QW'@%A W€& !'KKP'Ou e";Y'[]/W]( (€& =QW'@eA e";']\]7W(QuO73 S(Qau& Function WW\'[OS[zau\Q7tI'=a\3]3'[OS['/W'!'KKP $%TY&7'/u/\QS'D(]va]u7}'/&wa3W /u/\QS'S(Qau&'YQ\W/S]'(]D](]u7] (3%"R"'W(/u3ZOW'QaW=aW'@7ZQ3'\]Y]\3A !'KKP'WOZ]%W/S'Ou=aW'DQ('=[/3]%\Q7tOuS e";Y&7'3a==\}'DQ('[]/W](3 (3%"R"'(]7]OY]('Ou=aW'@7ZQ3'\]Y]\3A eTI$$Y&7'/u/\QS'(]D](]u7] e";Y&7'3a==\}'DQ(']\]7W(QuO73 =QU]('3a==\}'7a((]uW'(]Wa(u O1'*..8G8-16'G>):)'8P'*1'(D'J-11)JG-:',>8J>'8P'K*:G'-9'w!$$6',>8J>'8P'2P).'9-:'G>)'!$'Z[^ P81)'-2GK2G'9:-+'G>)'218GI'W>)'J-11)JG-:'P>)55'-9'w!$$'8P'*5P-'L:-21.).I 1 pps Input W>)':)*:'K*1)5'!'KKP'81K2G'8P'J-11)JG).'.8:)JG54'G-'G>)'!'KKP'81K2G'G-'G>)'=(3!$I'W>)'=(3!$ J*1'G8+)%G*L'G>)':8P81L').L)'-9'G>8P'81K2G'*1.':)K-:G'G>)'G8+)%G*L'0*52)P'08*'G>)'(3%"R"',8G> !1P':)P-52G8-1I'W>)'=(3!$'J*1'*5P-'K>*P)%5-JH'G-'G>)')EG):1*5'!'KKP'81K2G'N4'*.l2PG81L'8GP 9:)V2)1J4'-9'-K):*G8-1I W>)':)*:'K*1)5'!'KKP'81K2G'*5P-'G:8LL):P'*'!`P'-1)%P>-G'@a!$"fA'G-'.)G)JG'G>)'P41J>:-18^*G8-1 -9'G>)'!'KKP'81K2G'G-'G>)'!'KKP'-2GK2G'G-',8G>81'*'!`P',81.-,I'@W>)'!'KKP'-2GK2G'*5P-'G:8LL):P *'!`P'-1)%P>-G'@a!$"/AI'O9'G>)'G,-'!'KKP'K25P)P'>*0)':8P81L').L)P',8G>81'!`P'-9')*J>'-G>): G>)'u/u&'L*G)'@a!$!fA',855':)%G:8LL):'G>)'!IXP'-1)%P>-G'@a!$R/A',>8J>'>-5.P'G>)'!'KKP 3}u7':)5*4'@a!$BA'j-1IkA W>)'!`P'-1)%P>-G'G:8LL):).'N4'G>)'!'KKP'81K2G'*5P-'G:8LL):P'*'B$+P'-1)%P>-G'@a!$RfA',>8J> 8P'2P).'G-'N581H'G>)'9:-1G'K*1)5'j!'KKP'81K2Gk'\]&I'W>)'B$+P'-1)%P>-G'*5P-'>-5.P'-99 *..8G8-1*5'G:8LL):P'-9'G>)'!`P'-1)%P>-G'21G85'8G'G8+)P%-2G6':).2J81L'G>)'K:-N*N858G4'-9'9*5P) P41J'.)G)JG8-1'81'G>)'J*P)'G>*G'G>)'2P):pP'!'KKP'81K2G'8P':21181L'+2J>'9*PG):'G>*1'!'KKPI FS725 Rubidium Frequency Standard 26 Circuit Description Lock and 1 pps output W>)'=(3!$'-2GK2GP'5-JH'PG*G2P'*1.'!'KKP'-1'=81'!I'W>8P'-2GK2G',855'>*0)'*'7ZQ3'>8L>'5)0)5 @TYA'21G85'G>)'218G'5-JHP'8GP'J:4PG*5'-PJ855*G-:'G-'G>)':2N8.82+'K>4P8JP'K*JH*L)I'U>)1'G>)'218G 5-JHP6'=81'!',855'L-'G-'*'7ZQ3'5-,'5)0)5'@$YA'*1.'K25P)'>8L>'9-:'!$`P'*G'!'KKPI /1'(7'985G):'@(!$$'r'7!$$A'G-L)G>):',8G>'G>)'3J>+8GG'G:8LL):'@a!$;/A':)J-0):P'G>)'5-JH PG*G2P'*1.'L*G)P'G>)'!'KKP'-2GK2G'j-99k',>)1'G>)'218G'8P'215-JH).I'W>)'3J>+8GG'G:8LL):'-2GK2G >-5.P'G>)'\Q7t':)5*4'j-1k',>)1'G>)'218G'8P'5-JH).I W>)'!'KKP'-2GK2G'9:-+'G>)'=(3!$'8P'L*G).'N4'a!$!/'*1.'N299):).'N4'G>)'-JG*5'.:80):'a!$$I W>)'L*G).'!'KKP'8P'*5P-'K*PP).'G-'G>)'-KG8-1*5'-2GK2G'+-.25)PI'W>)'<'-2GK2GP'-9'a!$$'*:) L*1L).'G-L)G>):'G>:-2L>'G,-'!$$b':)P8PG-:P'@(!$!'r'(!$"A'G-'.:80)'G>)':)*:'K*1)5'!'KKP QaW'08*'*'N*521'@W!$$AI''W>)'!'KKP'-2GK2G'8P'81G)1.).'G-'.:80)'T$'b'5-*.P'G-'"ITY&7 :)V28:81L'T$+/'-9'J2::)1G'.2:81L'G>)'!$`P'K25P)I'7*:)',*P'G*H)1'G-'J-1981)'G>8P'5*:L)'J2::)1G K25P)'G-'G>)'8++).8*G)'*:)*'*:-21.'G>)'!'KKP'.:80):?'G>):)'8P'*1'8P-5*G).'L:-21.'K5*1)',>8J> 8P'5-J*554'N4K*PP).'N4'*'RR$`D'J*K*J8G-:'@7!$"A'*1.'*'I!`D'J*K*J8G-:'@7!$!A6'G>)'P4PG)+pP eTY&7'P2KK54'8P'8P-5*G).'N4'*';Bb':)P8PG-:'@(!!"A6'*1.'G>)'N*521'@W!$$A'j:)V28:)Pk'G>*G'*55 -9'G>)'-2GK2G'J2::)1G':)G2:1P'G-'G>)'5-J*5'L:-21.I RS-232 Interface W>)'=(3!$'J*1':)J)80)'P):8*5'.*G*'-1'=81'B'*1.'G:*1P+8G'P):8*5'.*G*'-1'=81';I'W>)'7ZQ3 5)0)5P'9:-+'G>)'=(3!$'*:)'5)0)5'P>89G).'N4'*1'(3%"R"'81G):9*J)'@a!$TA',>8J>'>*P'*'J>*:L) K2+K'G-'L)1):*G)'G>)'c!$Y&7':)V28:).'N4'G>)'(3%"R"I'/JG808G4'-1'G>)'(3%"R"'581)P'8P .)G)JG).'N4'.8-.)P'@&!$$'*1.'&!$!A'*1.'(7'1)G,-:HP'@(!$<6'7!$B'r'(!$#6'*1.'7!$8J>'.:80)'G>)'9:-1G'K*1)5'\]&P'@(3%"R"'()J)80)'*1.'3)1.A'08*'3J>+8GG'G:8LL):'@a!$;& *1.'a!$;]AI'W>)'J>*:L)'K2+K'(3%"R"'81G):9*J)'>*P'*'P)K*:*G)'L:-21.'K5*1)'*1.'8P'5-J*554 N4K*PP).'*1.'8P-5*G).'9:-+'G>)'P4PG)+pP'eTY&7'P2KK54I Front Panel LEDs /'P+*55'=7f'+-21G).'-1'G>)'9:-1G'K*1)5'J*1'>-5.'2K'G-'#'\]&P'*1.'G>)8:'J2::)1G'58+8G81L :)P8PG-:P'@-154'P8E'*:)'2P).'81'G>8P'K:-.2JGIA'/1'\]&'8P'58G',>)1'G>)'J-::)PK-1.81L'581)'8P K255).'5-,'08*'*'!$'J-1.2JG-:':8NN-1'J*N5)I FS725 Rubidium Frequency Standard Circuit Description 27 Rubidium Power Supplies and RF Amplifiers (Sheet 2 of 2) Power Supplies /'2180):P*5'81K2G6'e";Y&7_TTU'-2GK2G6'P,8GJ>81L'P2KK54'K-,):P'G>)'D3B"TI'/9G):',*:+%2K G>)'D3B"T'.:*,P'-154'*N-2G'!_R:.'-9'G>)':*G).'K-,):'9:-+'G>)'P2KK54',>8J>'8+K:-0)P :)58*N858G4'*1.':).2J)P':8KK5)I'W>)'-2GK2G'-9'G>)'K-,):'P2KK54'8P'92:G>):'985G):).'N4'K*PP80) \7'1)G,-:HP'@\!6'\"6'7"$$6'\"$$'*1.'7"$!A'N)9-:)'N)81L'*KK58).'G-'G>)'=(3!$':2N8.82+ 9:)V2)1J4'PG*1.*:.I W>:))%G):+81*5':)L25*G-:P'@a"$$6'a"$!'*1.'a"$RA'*:)'2P).'G-'L)1):*G)'P4PG)+P'0-5G*L)P'-9 e"$Y&76'e!$Y&7'*1.'eTY&7I'/'0):4'V28)G'eTI$$Y&7':)9):)1J)'8P'K:-08.).'N4'a"$"I'/ G:*1P8PG-:'@v"$$A'8P'2P).'*P'*'J2::)1G'N--PG'9-:'G>)'eTI$$Y&7':)9):)1J)I 10 MHz Outputs W>)'=(3!$'K:-08.)P'*'!$'Z[^'P81)',*0)'-2GK2G'-1'*1'(D'J-11)JG-:I'W>)'-2GK2G'>*P'* P-2:J)'8+K).*1J)'-9'T$'b'*1.'*+K58G2.)'-9'!I;!YKK',8G>'0):4'5-,'K>*P)'1-8P)I'W>)'D3B"TpP !$'Z[^'-2GK2G'.:80):P',):)'.)P8L1).'G-'+*81G*81'G>)'5-,'K>*P)'1-8P)'-9'G>)'=(3!$pP -2GK2GP'*1.'G-':).2J)'G>)'>*:+-18J'.8PG-:G8-1',8G>'>8L>'-2GK2G%G-%-2GK2G'8P-5*G8-1I W>)'-2GK2G'*+K5898):P'@\ZB!B!pP'a"$;'r'a"$XA'>*0)'>8L>'N*1.,8.G>6'5-,'.8PG-:G8-16'5-, J2::)1G'1-8P)6'N2G':*G>):'>8L>'0-5G*L)'1-8P)'@!;1Y_√[^AI'/'G21).'G:*1P9-:+):'@W"$$A'8P'2P). G-'81J:)*P)'G>)'0-5G*L)'@*1.'P-2:J)'8+K).*1J)A'-9'G>)'=(3!$pP'!$'Z[^'-2GK2G'G-'*0-8. .)L:*.81L'G>)'-2GK2G'1-8P)I'W>)'!$IBZ[^'G:*1P9-:+):'8P'G21).'.-,1'G-'!$'Z[^'N4'*1 *..8G8-1*5'J*K*J8G-:'-1'G>)'K:8+*:4'P8.)'-9'G>)'G:*1P9-:+):I'@W>)'G:*1P9-:+):P'>*0)'*';BKD J*K*J8G-:'81G):1*554IA'W>)'RIT?!'G:*1P9-:+):'81J:)*P)P'G>)'!$'Z[^'*+K58G2.)'G-'*N-2G'TYKK6 G>)'P-2:J)'8+K).*1J)'G-'*N-2G'X$$Ω6'*1.':).2J)P'>*:+-18J'.8PG-:G8-1I'/'!$Y&7'N8*P'@9:-+ a"$TA'8P'*..).'G-'G>)'G:*1P9-:+):'P)J-1.*:4'P-'G>*G'G>)'TYKK'-2GK2G'8P'J)1G):).'81'G>) J-++-1'+-.)'81K2G':*1L)'-9'G>)'-K'*+KP'@,>8J>'*:)'-K):*G).'9:-+'e"$Y&7IA W>)'-K'*+KP'@a"$;'*1.'a"$XA'*:)'-K):*G).',8G>'*'1-+81*5'L*81'-9'"I;I'W>)'L*81'J*1'N) *.l2PG).',8G>'="$$'-:'="$!'G-'J*58N:*G)'G>)'*+K58G2.)'-9'G>)':)*:'K*1)5'!$'Z[^'-2GK2GPI'W>) -K'*+KP'.:80)'T$'Ω'5-*.P'08*'*'G21).'-2GK2G'G:*1P9-:+):'*1.'*'R:.'.)L:))'7*2):'5-,'K*PP 985G):I'W>)'G:*1P9-:+):'8+K).*1J)'+*GJ>)P'G>)'2P):'5-*.'G-'G>)'*+K5898):6':).2J)P'0-5G*L) 1-8P)6'*1.'81P2:)P'G>*G'*55'-9'G>)'-2GK2G'J2::)1G',855':)G2:1'G-'G>)'8P-5*G).'L:-21.I'=*PP80)'\7 985G):P'-1')*J>'K-,):'P2KK54'*5P-'8+K:-0)P'J>*11)5%G-%J>*11)5'8P-5*G8-1I'W>)'-2GK2G'985G): :).2J)P'G>)'>*:+-18J'.8PG-:G8-1'N4'*1'*..8G8-1*5'!T'.fI /1-G>):'*+K5898):'@a"$)'-KG8-1*5'-2GK2G +-.25)PI'W>8P'*+K5898):'8P'-K):*G).',8G>'1-+81*5'L*81'-9'"I;',>8J>'8P'*.l2PG).'G-'K:-08.)'T YKK'G-'G>)'-KG8-1*5'-2GK2G'+-.25)PI'W>)'P-2:J)'8+K).*1J)'-9'G>)'581)'8P'"T$'Ω'*1.'8G'>*P'*1 -99P)G'-9'!$'Y&7I FS725 Rubidium Frequency Standard 28 Circuit Description 5 MHz Output /'T'Z[^'-2GK2G'8P'J:)*G).'N4'J-10):G81L'G>)'!$'Z[^'P81)'81G-'*'PV2*:)',*0)6'J5-JH81L'*'&% G4K)'958K%95-K'G-'.808.)'G>)'9:)V2)1J4'N4'G,-6'*1.'985G):81L'G>)'T'Z[^'PV2*:)',*0)'G-'K:-.2J) *'5-,'.8PG-:G8-1'T'Z[^'P81)',*0)'-2GK2GI OG'8P'1)J)PP*:4'G-'81J:)*P)'G>)'P5),':*G)'-9'G>)'!$'Z[^'J5-JH'P8L1*5'G-'G>)'958K%95-K'P-'G>*G'G>) 1-8P)'*G'G>)'J5-JH'81K2G'.-)P'1-G'K:-.2J)'l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eTI$$Y':)9):)1J)'9-:'G,:)*P-1P?'G-':).2J)'G>)'1-8P)'-9'G>)'J5-JH'G>:)P>-5.'*1.'G-':).2J)'*+K58G2.)'+-.25*G8-1'-9'G>) -2GK2GI'@W>)'-2GK2GP'-9'G>)'958K%95-K'P,81L'N)G,))1'$'*1.'YJJ'*1.'P-'*14'1-8P)'-1'YJJ G:*1P5*G)P'.8:)JG54'81G-'*+K58G2.)'1-8P)6'G>):)N4'.)L:*.81L'G>)'K>*P)'1-8P)'-9'G>)'-2GK2GIA W,-'958K%95-KP'*:)'J5-JH).',8G>'G>)'-2GK2G'-9'G>)'J5*+K81L'*+K5898):I'Q1)'-9'G>)'958K%95-KP .:80)P'G>)':)*:'K*1)5'T'Z[^'-2GK2G'08*'("R!'r'("R"6'*'G21).'G:*1P9-:+):'@W"$RA6'*1.'*'TG> -:.):'7*2):'5-,%K*PP'985G):'@7";!%";<'r'\"$#%"!$AI'/'PG*1.*:.'!$IB'Z[^'G:*1P9-:+):'8P G21).'.-,1'G-'T'Z[^'N4'*..8G8-1*5'J*K*J8G*1J)'-1'G>)'K:8+*:4'-9'G>)'G:*1P9-:+):I'W>)'G21). G:*1P9-:+):'*1.'985G):'*GG)12*G)'>*:+-18JP'-9'G>)'T'Z[^'PV2*:)',*0)'N4'+-:)'G>*1'X$.f K:-.2J81L'*'5-,'.8PG-:G8-1'T'Z[^'P81)',*0)'*G'G>)':)*:'K*1)5'-2GK2GI'W>)'-G>):'T'Z[^ PV2*:)',*0)'8P'2P).'*P'*'J5-JH':)9):)1J)'9-:'G>)'-KG8-1*5'-2GK2G'+-.25)PI Signals to the Optional Output Modules /'!$%581)'N2P'J-11)JGP'P8L1*5P'9:-+'G>)'+*81'N-*:.'G-')*J>'-9'-KG8-1*5'-2GK2G'+-.25)PI 38L1*5P'*1.'L:-21.'K5*1)P'-1'G>8P'N2P'*:)'*::*1L).'G-':).2J)'J:-PP'G*5HI'W>:))'K-,):'P2KK58)P @e"$Y6'eTY'*1.'G>)'eTI$$Y':)9):)1J)A6'G>:))'L:-21.P'@*55'81'J-++-1A6'*1.'9-2:'P8L1*5P'@!$ Z[^'P81)6'T'Z[^'*1.'8GP'J-+K58+)1G6'*1.'G>)'L*G).'!'KKP'P8L1*5A'*:)'K*PP).'G-'*55'G>)'-KG8-1 +-.25)PI Optional Output Modules aK'G-'G>:))'-KG8-1*5'-2GK2G'+-.25)P'J*1'N)'81PG*55).'81'G>)'D3B"TI']*J>'+-.25)'K:-08.)P 9-2:'!$'Z[^'P81)'-2GK2GP6'-1)'T'Z[^'P81)'-2GK2G6'*1.'-1)'!'KKP'WW\'-2GK2GI'/55'-9'G>) -2GK2GP'*:)'81G)1.).'G-'.:80)'T$'Ω'5-*.P'*1.'*55'>*0)'G>)'P*+)'.:80)'5)0)5P6'K>*P)'1-8P)6'*1. .8PG-:G8-1'*P'G>)'PG*1.*:.'-2GK2GPI 38L1*5P'K*PP).'9:-+'G>)'+*81'N-*:.'*:)'N299):).'-1')*J>'-KG8-1'+-.25)I'W>)'!$'Z[^'P81) ,*0)'8P'N299):).'N4'aR$$',>8J>'-K):*G)P',8G>'*'L*81'-9'"'G-'-0):J-+)'G>)'*GG)12*G8-1'-9'G>) 81K2G'.808.):'2P).'-1')*J>'J>*11)5I'W-'8+K:-0)'.8PG-:G8-16'N8*P)P'*:)'*::*1L).'P-'G>*G'1-1) -9'G>)'!$'Z[^'*+K5898):P'>*P'*14'.J'J2::)1G'*G'G>)8:'-2GK2GI FS725 Rubidium Frequency Standard Circuit Description 29 W>)'T'Z[^'PV2*:)',*0)P'*:)'N299):).'N4'aR$TI'W>)'!'KKP'P8L1*5'8P'N299):).'N4'aR$XI'W:).2J)'J>*11)5%G-%J>*11)5'J:-PP'G*5H6'*55'J>*11)5P'*:)'K5*J).'-1'P)K*:*G)'L:-21.'K5*1)P'*1. -K):*G)'9:-+'5-J*554'N4K*PP).'K-,):'P2KK58)PI FS725 Rubidium Frequency Standard 30 Component Parts List FS725 Component Parts List FS725 (REV B) MAIN BOARD PARTS LIST Item Quantity Reference ! T 7!$$67!$R67!$;67"TX67"TB " R$ 7!$!67!$X67!$B67!$<67!$#6 7!!$67!!!67!!R67!!;67!!T6 7!!X67!!B67"!!67"!"67"!R6 7"!;67""!67"""67""#67"R!6 7"R"67"R;67"RT67"RX67"RB6 7"R<67"R#67"T$67"TR67"T; R R 7!$"67"$$67"$! ; !$ 7!$T67!!"67"$"67"$R67"$;6 7"$T67"$X67"$B67"$<67";# T X 7"!$67"!B67""T67";"67";R6 7";T X R 7"!T67""R67"R$ B ; 7"!X67"!#67"";67""B < ; 7"!<67""$67""X67""< # ! 7";$ !$ ! 7";! !! ! 7";; !" ! 7";X !R ! 7";B !; ! 7";<6'7"TT !T " 7"T!67"T" !X !B R 7"T<67"X$67"X" !< R 7"T#67"X!67"XR !# " &!$$6&!$! "$ X &!T$6&!T!6&!T"6&!TR6&!T;6'&!TT "! ! w!$$ "" ! 7Q/€'=/(W'QD'w!$$ "R X w!$!6w!$"6w!$<6w"$"6w"$R6'w"$; "; ! w!$R "T ! ]€W](u/\'=/(W'QD'w!$R "X ! w!$; "B ! w"$T "< ; w"T$6w"T!6w"T"6w"TR "# ; w"T;6w"TT6w"TX6w"TB R$ ; \!$"6\"$X6\"$<6\"!! R! ! \"$$ R" " \"$"6\"$; RR ! \"$# R; ! \"!$ RT R ="$$6="$!6="$" RX ; ("$#6("!B6("R;6(";$ RB " v!$$6v!$! R< ! v"$$ R# ! (!$$ ;$ X (!$!6(!$"6("$;6("$X6("""6'(""T FS725 Rubidium Frequency Standard Part I$$!a I!a SRS P/N T%R 25 (at 10MHz) ±1x10-10 over -20°C to +65°C baseplate < 2x10-11 for a 1Vdc supply change < 2x10-10 for 1 Gauss field reversal ±5x10-11 (72 hr off then 72 hr on) < 5x10-12 ±2x10-9 < 6 (starting at 25°C) < 7 (starting at 25°C) MHz Vrms ∆f/f ∆f/f dBc/Hz dBc dBc ∆f/f ∆f/f dB ∆f/f ∆f/f ∆f/f ∆f/f ∆f/f ∆f/f minutes minutes Other Electrical Power supply Supply current Protection RF protection Ext calibration Cal reference out RS-232 1pps measurement 1pps output set +24.0 (nom), +22 (min), +30 (max) 2.2 (warmup) , 0.6 (steady-state at 25°C) ± 30 (to any pin except rf output) 100 (stable with any termination) 0-5.00 5.00 ± 0.05 9600 (8 bits, no parity, 1 stop bit, 0V/5V levels with x on/x off protocol) ±10 (accuracy), 1 (resolution) ±10 (accuracy), 1 (resolution) Vdc A Vdc mA Vdc Vdc baud -20 to +65 (baseplate) -55 to +85 2.00 x 3.00 x 4.00 1.32 2 4-40 (4 places) Mates with ITT/Cannon DAM11W1S series °C °C inches lbs years ns ns Miscellaneous Temperature Storage Size Weight Warranty Baseplate threads Connector PRS10 Rubidium Frequency Standard Abridged Command List 5 Abridged Command List Commands consist of two-letter ASCII mnemonics. A command may be followed one or more numeric values, and punctuation. Command sequences end with a carriage return (ASCII 1310). All commands are case insensitive. Spaces (ASCII 3210) and linefeeds (ASCII 1010) are ignored. A command followed by a value is used to set a parameter to the value. A command followed by an exclamation point (! or ASCII 3310) indicates that the current value should be saved to EEPROM to be used as the initial value after the next reset. A command followed by a question mark (? or ASCII 6310) is used to request that the current value be returned. A command followed by an exclamation point and a question mark is used to return the EEPROM value. For example, the gain parameter determines the time constant used to lock the 10MHz oscillator to the rubidium hyperfine transition. Examples of the four forms of the gain parameter command are: GA? GA7 GA! GA!? ;returns the current value of the frequency lock loop gain parameter. ;sets the frequency lock loop gain parameter to 7. ;writes the value of the gain parameter to EEPROM for use after reset. ;returns the value of the gain parameter which is stored in EEPROM. All strings returned by the unit are terminated with a carriage return (ASCII 1310). In the verbose mode, strings are preceded with a linefeed (ASCII 1010) and terminated with a carriage return and a linefeed. If more than one value is returned by a command the values will be separated by a comma (ASCII 4410). When a unit is first turned “on”, it will send the string “PRS_10” (without the quotes) followed by a carriage return. Only commands in bold type are available to the end-user. The other commands are “factory only” commands which disabled at the factory. PRS10 Rubidium Frequency Standard 6 Abridged Command List Query Value Initialize RS? VB? ID? SN? ST? LM? Freq. Lock LO? FC? DS? SF? SS? GA? PH? SP? Magnetic Tuning MS? MO? MR? 1PPS Lock TT? TS? TO? PS? PL? PT? PF? PI? Set Value or Write Query Activate EEPROM EEPROM RS 1 VB value SN value SN! SN!? LM value RC 1 LM! RC! LM!? LO value FC high,low FC! FC!? SF value SS value GA value PH value SP r,n,a SS!? GA!? PH!? SP!? MS value MO value TS value TO value PP value PS value PL value PT value PF value PI value SS! GA! PH! SP! MO! MO!? TS! TO! TS!? TO!? PS! PL! PT! PF! PS!? PL!? PT!? PF!? PRS10 Rubidium Frequency Standard Description Restart Verbose mode Read ID string Read unit serial number Read six status values Lock pin mode Recall factory calibration Frequency lock loop status Frequency control values Read detected signals (ω and 2ω) Set frequency offset Set Slope (SF calibration) FLL Gain parameter Phase angle parameter Set synthesizer parameters Magnetic switching Magnetic Offset Magnet read Time-tag (1pps input) Time slope cal. (1pps input) Time-tag offset Place pulse (1pps output) Pulse slope cal. (1pps output) Phase lock (to 1pps input) Phase lock time constant Phase lock stability factor Phase lock integral term Abridged Command List Query Value D/A Control SD0? SD1? SD2? SD3? SD4? SD5? SD6? SD7? Set Value Write Query EEPROM EEPROM SD0,value SD1,value SD2,value SD3,value SD4,value SD5,value SD6,value SD7,value SD0! SD1! SD2! SD3! SD4! SD5! SD6! SD7! Analog Test (12-bit values) AD0? AD1? AD2? AD3? AD4? AD5? AD6? AD7? AD8? AD9? AD10? AD11? AD12? AD13? AD14? AD15? Analog Test (8bit values) AD16? AD17? AD18? AD19? SD0!? SD1!? SD2!? SD3!? SD4!? SD5!? SD6!? SD7!? 7 Description Set DAC (RF amplitude) Set DAC (1pps delay) Set DAC (lamp intensity) Set DAC (lamp temperature) Set DAC (crystal temperature) Set DAC (cell temperature) Set DAC (10 MHz amplitude) Set DAC (RF deviation) Spare (J204) +24V(heater supply) / 10. +24V(electronics supply) /10 Drain voltage to lamp FET / 10 Gate voltage to lamp FET / 10 Crystal heater control voltage Resonance cell heater control Discharge lamp heater control Amplified ac photosignal Photocell’s I/V converter / 4 Case temperature (10 mV/°C) Crystal thermistors Cell thermistors Lamp thermistors Frequency calibration pot Analog ground VCXO varactor voltage VCO varactor voltage AGC for RF RF PLL lock signal PRS10 Rubidium Frequency Standard 8 Theoretical Overview Theoretical Overview of Rubidium Frequency Standards Rubidium is an alkali metal (like lithium, sodium, potassium and cesium). There are two naturally occurring isotopes of rubidium, Rb85 and Rb87, which have relative abundances of 72% and 28% respectively. The metal has a melting point of 39°C. The alkali metals behave similarly: they have one electron outside an inert core. Most of the chemical, electronic and spectroscopic properties of these elements are determined by this outer electron. The deep red glow of a low power rubidium discharge lamp is due to the resonance line transitions of the outer electron as it emits a red photon and drops back to the ground state. The ground state of Rb87 is split by a very small energy due to the relative orientation of the magnetic spins of the electron and the nucleus. The split corresponds to the energy of a photon with a (microwave) frequency of 6.834,682,612,8 GHz. It is this hyperfine transition frequency which will be used to stabilize the 10 MHz output of the PRS10. To see how this is might be done, Figure 1 shows a typical physics package which uses a discharge lamp, an isotopic filter, and a resonance cell. We will see that the amount of light which passes through the resonance cell to the photodetector can be reduced when the resonance cell is exposed to microwaves at the hyperfine transition frequency. To simplify the discussion, we will assume that the light from the Rb87 discharge lamp consists of just two lines corresponding to transitions from a single excited state to the split ground state. The filter cell contains Rb85 vapor which also has a split ground state and an isotopic shift (relative to Rb87) as well. An important coincidence exists: one of the lines from the Rb87 discharge corresponds one of the transitions in Rb85. This will allow us to reduce the intensity of this line by passing the Rb87 discharge light through the Rb85 vapor. Normally, atoms in the ground state will be equally distributed between the split states, as the splitting is much less than the thermal energy of the atoms in the vapor. This distribution is modified by the filtered light from the discharge, by a process called “optical pumping”. Suppose that the filter can completely remove one of the two discharge lines. The remaining light can be absorbed by Rb87 atoms in the resonance cell which are in the lower ground state, moving them to the upper state. When they decay from the upper state, they fall with equal probability into either ground state. As this continues, population will be moved from the lower ground state to the upper ground state, circulating through the upper state. As the population in the lower ground state is decreased, the amount of light which reaches the photodetector will increase, as the number of atoms which can absorb the radiation is reduced. PRS10 Rubidium Frequency Standard Theoretical Overview Rb87 Discharge lamp Rb85 Isotopic Filter 9 Rb87 Resonance Cell Photocell Photons RF @ 6.834GHz 5p ≅780nm 6,834,682,612.8Hz 5s Rb87 Emission Rb85 Scattering Rb87 Optical Pumpin Figure 1. Hypothetical Rubidium Physics Package Now, if we apply a microwave field at the frequency corresponding to the hyperfine transition frequency (6.834,682,612,8 GHz), the populations in the ground state will mix, and the amount of light reaching the photodetector will decrease. The PRS10 uses the “integrated filter” topology: rather than a separate filter cell, the resonance cell contains a mixture of the two rubidium isotopes, along with a buffer gas. The lamp also contains a mixture of isotopes. The isotopic mixtures, buffer gases, and operating conditions are chosen so as to minimize temperature coefficients and intensity shifts of the apparent hyperfine transition frequency. PRS10 Rubidium Frequency Standard 10 Theoretical Overview The apparent transition frequency will be shifted by about 3 kHz from the natural transition frequency by the buffer gas and discharge lamp spectral profile. The transition frequency differs slightly for each unit, depending on the fill pressure, etc. The transition frequency is also tuned over a few Hertz by a magnetic field which may be varied. In the PRS10, the rubidium physics package acts as a very stable frequency detector for a frequency around 6.834 GHz. By using a microwave frequency synthesizer which is referenced to the 10 MHz OCXO, the 10 MHz may be stabilized to the rubidium hyperfine transition frequency. PRS10 Rubidium Frequency Standard PRS10 Overview 11 PRS10 Overview All compact rubidium frequency standards discipline a crystal oscillator to the hyperfine transition frequency in the ground state of rubidium. Several different topologies have been developed. A major difference in these designs is the method chosen to lock a standard output frequency (usually 10 MHz) to the (essentially arbitrary) hyperfine transition frequency at about 6.834 GHz. Block Diagram Figure 2 shows a block diagram for the PRS10 Rubidium Frequency Standard. The design of the PRS10 is quite different from other rubidium frequency standards leading to several feature and performance benefits. Ovenized Oscillator The output from PRS10 comes directly from a 10 MHz oven stabilized, 3rd overtone, varactor tuned, SC-cut crystal oscillator. The varactor is tuned by a 22bit digital-to-analog converter which provides a full scale tuning range of ±2 ppm. The very fine step size (≈1:10-12) maintains the low noise inherent to the SC-cut resonator, yet the full-scale range is sufficient to compensate for crystal aging over the lifetime of the unit. This approach provides a 10 MHz output with extremely low phase noise which is virtually free of spurs. Frequency Synthesizer The 10 MHz also serves as the reference source to the frequency synthesizer which generates RF at about 359.72 MHz. The RF is multiplied by a factor of 19x in a step recovery diode to provide the microwave frequency (at about 6.834 GHz) which is used to interrogate the physics package. (The apparent hyperfine transition frequency varies with each physic package due to variations in buffer gas fill pressure, etc.) The frequency synthesizer has two important characteristics: a step size of about 1:10-9 and very low phase noise output. The small step size is required so that only small magnetic fields will be needed to tune the apparent hyperfine transition frequency between the steps of the synthesizer. The low phase noise is required so as not to degrade the signal from the physics package, which would lead to a noisy frequency lock, and degraded output stability. These two characteristics require a dual loop design for the frequency synthesizer. The inner loop consists of the 359.72 MHz VCO which is directly phase locked to a 3rd overtone 22.48252 MHz crystal oscillator. This loop has a large natural frequency of about 400,000r/s. The VCO’s phase noise at 359.72 MHz is very close to the phase noise of the crystal (plus 24 dB for the multiplication factor of 16). PRS10 Rubidium Frequency Standard 12 PRS10 Overview 22-bit DAC (10-12 /bit) Matching Transformer 10MHz Low Noise Ovenized Oscillator 50Ω Output CPU Control 10MHz Synthesizer Reference Dual Modulus Synthesizer 22.4825MHz VCXO 359.72MHz RF VCO ∆f≅1E-9 / step ωn≅10r/s 1/16 ωn≅400,000r/s 359.72MHz Gain Leveling Amp Temperature Controlled 150MHz Lamp Oscillator Step Recovery Diode Data to CPU Photocell Rb87 Enriched Discharge Lamp Resonance Cell Transimpedance Amplifier 12-bit ADC Figure 2. Rubidium Frequency Standard Block Diagram The outer loop compares the RF frequency to the 10 MHz. This loop provides high resolution by dividing the RF and 10 MHz by large numbers, and consequently operates at a low comparison rate (typically 4 kHz). This loop has a low natural frequency (about 10 r/s) so the phase noise of the RF more than a few Hz from carrier will be determined by the inner loop. The outer loop slowly disciplines the frequency of the inner loop’s crystal, keeping it locked to the 10 MHz reference. PRS10 Rubidium Frequency Standard PRS10 Overview 13 The frequency synthesizer is set to the nearest frequency above the apparent hyperfine transition for the unit’s physics package. A magnetic field is used to tune the physics package’s apparent hyperfine transition frequency up to the synthesizer frequency. A 70 Hz digitally synthesized sine wave is used to phase modulate the inner loop. (The outer loop bandwidth is too small to suppress this modulation.) This generates an RF output, which when multiplied to 6.834 GHz, sweeps by about 300 Hz around the apparent hyperfine transition frequency. By sweeping through the transition at 70 Hz, the output from the photocell will have an ac component at 140 Hz, when centered on the transition. There will be an ac component at 70 Hz if we are off to one side of the transition: the phase of the 70 Hz component is used to determine if the RF is above or below the transition. Physics Package The physics package consists of a discharge lamp (enriched with Rb87) and an integrated filter and resonance cell. The discharge lamp operates at about 150 MHz. The lamp oscillator can provide up to 300 Vpp to start the lamp, which drops to about 100 Vpp during normal operation. The lamp oscillator voltage and current are carefully regulated to provide a consistent intensity and low noise. The resonance cell is inside a mu-metal shell to reduce the frequency pulling effects of external magnetic fields. The apparent hyperfine transition frequency may be quadratically tuned over a range of about ±2 x 10-9 by the magnetic field coil. (The frequency shift is always positive, regardless of the direction of the magnetic field.) To further reduce the effects of external magnetic fields, the current in the field coil is switched at 5 Hz. An external field which adds to the coil’s field will increase the apparent transition frequency, and an external field which opposes the coil’s field will decrease it. By alternating the coil’s field and averaging, the effect of an external field can be reduced. Control Algorithm The microcontroller is responsible for (1) generating the 70 Hz phase modulation of the RF to probe the physics package, (2) synchronously detecting the amplitude and phase of the photosignals at 70 Hz and 140 Hz, and (3) digitally filtering the error signal to lock the 10 MHz SC-cut ovenized oscillator to the rubidium hyperfine transition. The 70 Hz digitally synthesized phase modulation waveform is generated via a 12-bit DAC in 32 discrete steps. A low pass filter is used to remove image frequencies from the modulation waveform. The microcontroller’s hardware timers are used synchronize updating of the DAC so as to eliminate sample jitter. The modulation waveform has very little distortion, noise or spurs, and is precisely 70 Hz. The photosignal is amplified and bandpass filtered before being converted by a 12-bit ADC. The microcontroller multiplies the ADC samples by table data corresponding to sines and cosines at 70 Hz and 140 Hz. The products are summed over a frame of 14 modulation cycles PRS10 Rubidium Frequency Standard 14 PRS10 Overview which completely eliminates signal components at 5 Hz, (and at any integer multiple of 5 Hz including 50 Hz, 60 Hz, 70 Hz and 140 Hz) from the error signal, so that there will be no spurs at the modulation frequency in the 10 MHz output. The summed product corresponding to the detected signal at 70 Hz and 0° is used to frequency lock the 10 MHz oscillator to the Rb hyperfine transition frequency. This value is filtered in a simple, first order, IIR digital filter. The filter coefficient determines the frequency lock loop time constant. Time constants from 1 s to 128 s are available to optimize the output stability of the 10 MHz. Initial Locking When power is first applied to the unit, the EFC (the electronic frequency control, or, the voltage applied to the varactor in the 10 MHz SC-cut oscillator) is set to the last value for which the unit was locked. As the 10 MHz oscillator heats to its operating temperature, the output frequency will increase smoothly to converge on 10 MHz. In most cases, the output frequency will be within 0.1 Hz of 10 MHz even before the lock to rubidium is achieved. After the lamp starts, and the physics package settles to its operating temperature, a resonance signal will be detected by the processor, and used to lock the crystal oscillator to rubidium. In the case that no signal is detected, or if the signal is lost during normal operation, the processor will suspend the frequency lock loop, and maintain the varactor voltage to the 10 MHz ovenized oscillator at a fixed level. Any of the following conditions would cause the CPU to suspend lock: 1) 2) 3) 4) 5) The detected signal at 140Hz is very low. The discharge lamp light level is outside an acceptable range. The RF synthesizer is unlocked. The RF AGC level is pinned high or low. The VXCO varactor voltage is outside the acceptable range. Suspending lock will prevent a radical change in output frequency in the case of a physics package failure. So, in the case of most failures which cause loss of the lock to rubidium, the 10 MHz will maintain a stable output, with an aging of a few parts in 1010 per day. Locking to External 1pps The PRS10 may be locked to an external 1pps source (from a GPS or LORAN receiver, for example) by applying a 1pps pulse to the 1pps input (pin 5 on the main connector). A second order digital phase lock loop (PLL) is used to adjust the frequency of the PRS10 to match the frequency of the 1pps source over long time intervals. The block diagram of this PLL is shown in Figure 3. The “phase detector” is the time-tagging circuit and firmware, which has a gain of Kdet = 1bit/ns. The loop filter is a digital filter consisting of an optional pre-filter and a standard proportional-integral controller PRS10 Rubidium Frequency Standard PRS10 Overview 15 (PI controller) with programmable proportional and integral gains. The VCO is the rubidium frequency standard, whose frequency, f, is tuned by the magnetic field via the SF command parameter with a sensitivity for its 1pps output of Kvco = 0.001 ns / bit-s, or (1 part in 1012) / bit. The response function for each of the elements of the digital PLL is also indicated in the figure in terms of the standard Laplace variable s. External 1pps input Pre-filter Time-tag circuit Kdet 1 τ3s + 1 1 s Proportional and Integral Gains Ap + 1 τ1 s VCO Kvco 10MHz Output 1 10,000,000 Figure Figure3.3.External External1pps 1ppsPhase PhaseLocking LockingBlock BlockDiagram Diagram The PI controller is programmed by choosing an appropriate integrator time constant, τ1, and a stability factor, ζ. τ1 determines the natural time constant, τn, of the PLL for following a step in phase of the reference, while ζ determines the relative rise time and ringing of the PLL in response to the step. The value of ζ also represents the tradeoff in the equivalent noise bandwidth verses peaking in the passband near the natural frequency of the response function. The PRS10 accepts integrator time constants, τ1, ranging from 28 to 222 seconds in powers of 2. The natural time constant is given by τ n = τ1 / K det K vco = (1000s )τ1 . Thus, the PRS10 provides natural time constants ranging from 506 seconds to 18.0 hours. While the integrator time constant ( τ1 ) determines the natural time constant ( τn ), it is the natural time constant which characterizes the loop response. The PRS10 accepts stability factors ranging from 0.25 to 4.0 in powers of 2. The default value of ζ = 1.0 corresponds to a critically damped response; ζ < 1.0 and ζ > 1.0 correspond to under-damped and over-damped responses respectively. PRS10 Rubidium Frequency Standard 16 PRS10 Overview With τ1 and ζ specified, the proportional gain, Ap, of the controller is given by the equation Ap = 2ζ / K det K vcoτ1 = 2ζ / ( 0.001s-1 )τ1 . With the default time constant, τ1, of 65,536 seconds and a stability factor, ζ, of 1.0, the proportional gain will be about 0.25. In this case the instantaneous frequency of the rubidium source will be adjusted by about 0.25 parts in 1012 per nanosecond of time-tag measured. The PRS10 also provides an optional pre-filter. The pre-filter is enabled by default, but it can be disabled by sending the command LM0, which puts the PRS10 into lock mode 0. When the pre-filter is enabled, the PRS10 will exponentially average the time tags output by the “phase detector” before passing the result to the PI controller. The time constant of the prefilter, τ3, is hard coded to be τn/6.0 in order to obtain the maximum benefits of the averaging while simultaneously insuring that the PLL will be stable Use of the pre-filter is recommended when locking to references that have poorer short term stability than the PRS10, but better long term stability. Locking to the 1pps output by GPS is a prime example of such a case. Use of the pre-filter dramatically reduces the digital PLL’s sensitivity to the sort term jitter of 50 to 300 ns present on the GPS reference 1pps. The GPS reference also has a significant amount of 1/f noise associated with it. Very long time constants are therefore required to prevent the PRS10 from following this noise too closely. The PRS10 provides natural time constants of up to 18.0 hours, which will allow the PRS10 to follow GPS over time scales on the order of a day, but retain the superior short term stability of the rubidium clock. When locking to a reference that has short term stability comparable to the PRS10, disabling the pre-filter is recommended because it will allow the PRS10 to better track the phase of the reference. In lock mode 0, the PRS10’s digital PLL will approximate one of the following three equations depending on the value of ζ: ∆T ( t ) = F0 − ζ∆T ( 0) / τ n 1 − ζ 2 / τn − ζt − ζt e τn sin( 1 − ζ 2 t / τ n ) + ∆T ( 0)e τ n cos( 1 − ζ 2 t / τ n ) −t −t ∆T ( t ) = t[ F0 − ∆T ( 0 ) / τ n ]e τn + ∆T ( 0 )e τ n ∆T ( t ) = [ − F0 − (ζ + ζ 2 − 1 )∆T ( 0) / τ n 2 ζ − 1 / τn for ζ < 1 2 ]e [F − (ζ − 0 for ζ = 1 − (ζ + ζ 2 −1 ) t τn + ζ 2 − 1)∆T ( 0) / τ n 2 ζ − 1 / τn 2 ]e −(ζ − ζ 2 −1 ) t τn for ζ > 1 ∆T(0) is the initial offset in phase of the PRS10 from the reference. F0 is the initial offset in frequency of the PRS10 from the reference before the digital PLL is enabled. ∆T(t) details how the PRS10 approaches the phase of the reference as a function of time. With the default PRS10 Rubidium Frequency Standard PRS10 Overview 17 time constant, τ1 = 65,536s, and stability factor, ζ = 1, the PRS10’s 1pps output will exponentially approach the phase of the reference 1pps input with a time constant τn = 8,095 seconds or approximately 2¼ hours. In lock mode 1, the equations describing ∆T(t) are qualitatively similar to those presented above, but generally can only be solved numerically. The locking algorithm of the PRS10 proceeds as follows: • The 1pps PLL is enabled when the unit is turned-on or restarted if the PL parameter stored in the unit’s EEPROM is “1”. • The PLL will begin to control the frequency of the rubidium frequency standard when 256 consecutive “good” 1pps inputs (i.e., 1pps inputs which are within ±2048 ns of the first timetag result, modulo 1 s) are received. • After receiving 256 consecutive “good” 1pps inputs, the 1pps pulse delay is set to the last of the 256 time-tag values. (For example, if the last of the 256 “good” time tag values is 123,456,789 ns then the program will set the 1pps output delay to 123,456,789 ns, which moves the 1pps output by 123,456,789 ns, so that new time-tag values will be about zero.) Also, the current value of the SF parameter (which adjusts the frequency of the rubidium frequency standard over the range of ± 2000 parts in 1012) is used to initialize the integrator, Int(0). (The current value of the SF parameter may be from the internal calibration pot position, an external calibration voltage, the value from a previously received SF command, or the value left over from a previous PLL lock.) If the pre-filter is enabled, the exponential filter for the time tags is zeroed. • The unit will lock the frequency of the PRS10 to the “good” 1pps input pulses. “Bad” 1pps inputs (1pps inputs with time-tags greater than 1,024 ns from the last “good” 1pps input) will be rejected. The frequency parameter, f, to the SF command will be updated with each “good” time-tag result, ∆T(n), as follows: The pre-filter : if LM0 ∆T (n+1) = ∆T(n) The pre-filter : if LM1 ∆T (n+1) = (1.0 – ∆t/τ3) ∆T (n) + (∆t / τ3) ∆T(n) The integral term: Int(n+1) = Int(n) – ( ∆T (n+1) / τ1)Kdet∆t The proportional term: Pro(n+1) = -Ap ∆T (n+1)Kdet The frequency setting:f(n+1) = Pro(n+1) + Int(n+1) In the above equations, ∆t is the time between phase comparisons, which is one second for the PRS10. The frequency control value, f, ranges over ±2000 bits. If the new f value exceeds 2000, it is set to 2000. If the new f value is less than -2000, it is set to -2000. If the new integral term exceeds 2000, it is set to 2000. If the new integral term is less than 2000, it is set to -2000. This will prevent “integrator wind-up” in the case that the f-value is pinned for a long time to slew the 1pps output in line with the 1pps input. PRS10 Rubidium Frequency Standard 18 PRS10 Overview The output of the digital filter, f, is used as the frequency control parameter for the SF (set frequency) command, which is updated once a second. • The PLL will be aborted and restarted if there are 256 consecutive “bad” 1pps inputs. (This could happen if the 1pps input is moved suddenly by more than 1,024 ns.) The PLL will also be aborted and restarted if the measured time-tag value for a “good” 1pps input exceeds ±4 ns/s * τ 1. (For τ 1’s default value of 65,536 seconds, the PLL will restart if the absolute value of a “good” time-tag is greater than 262,144 ns. This could happen if the 1pps input is more than a few parts in 10-9 off the correct frequency for a long time.) CPU Tasks In addition to the frequency lock loop control, the microprocessor is responsible for a variety of other tasks. The CPU sets D/A values which control the microwave amplitude, the lamp intensity, the 10 MHz output amplitude, and set the temperature of the crystal, lamp and resonance cell. The CPU will also controls peripheral electronics to output a 1pps pulse (with 1ns placement) and measure the time for a 1pps input pulse (with 1 ns resolution). There is an RS-232 interface which allows closed-case calibration of the PRS10. This capability may also be used to servo the 10 MHz or 1pps outputs to another frequency or time source in a system. For example, this would allow the PRS10 to be locked to the 1pps from a GPS receiver with a long time constant to eliminate aging. PRS10 Rubidium Frequency Standard Applications 19 PRS10 Applications In virtually all cases, the PRS10 may be “dropped into” applications which use the Efratom FRS-C-1A8A4C (10 MHz sine output, -5°C to +65°C) or the FRS-N-1A8A4B (10 MHz sine output, -55°C to +65°C). Some customers may wish to evaluate the PRS10 on the bench. To facilitate this, SRS can provide a connector adapter, power supply and RS-232 cable. The adapter breaks-out the Cannon plug on the PRS10 to a power connector (2.1 mm with +24 V to center pin), three BNCs (10 MHz and 1pps output and 1pps input), and a DB9 (for the RS-232). The adapter also has status indicators for power, lock and RS-232 activity. This kit allows the PRS10 to be operated from 110-240 Vac (50/60 Hz), provides for a direct connection to a PC via a serial port (typically COM2:), and allows the use of standard BNC cables. The PRS10 may also be operated with a customer supplied connector (Cannon series DAM11W1S with coaxial insert DM53740-5008 for RG178 cable) from a bench dc power supply. The power supply should be able to supply 2.2 A at +24 Vdc. Interface Connector Pin Name Description 1 2 3 4 5 6 7 8 9 10 coax LOCK/1PPS POT WIPER POT TXD/PHOTO 1PPS_IN/PHOTO +24(HEAT) RXD/EFC POT + +24(CLEAN) GROUND 10MHz Lock indication and 1pps output. (See LM command) Ext. freq. calibration. Nom:+2.50 V. 0-5 V for ±2x10-9 Ground reference for external frequency calibration. RS-232 data output or photo I/V monitor output 1pps input for time-tagging or photo-amp output +24 Vdc supply for discharge lamp and heaters RS-232 data input or EFC monitor output +5.00 Vdc reference output for external freq. cal. pot. +24 Vdc supply for electronics (not heaters or lamp) Case ground and power supply return 10 MHz sine output on center conductor Configuration Notes The functions of three pins (4, 5 and 7) on the interface connector may be modified by internal hardware jumpers. The function of the LOCK output may be modified via RS-232. Pin 1: LOCK/1PPS output. The default configuration is: +5 V indicates that the unit is not locked to rubidium (as during warm-up), 0 V indicates a successful lock of the 10 MHz oscillator to rubidium, pulsing high for 10 µs at a 1pps rate. The 1pps output may be moved earlier by any interval from 1ns to 999,999,999 ns via RS-232 command. The unit may be configured to omit the 1pps output via the LM command (via RS-232). PRS10 Rubidium Frequency Standard 20 Applications Pin 4: TXD/PHOTO The default configuration uses this pin as an output for RS-232 data. Many system parameters (including the lamp intensity) may be monitored via the RS-232 interface. The function of this pin may be changed to an analog monitor for the lamp intensity by removing one resistor (R347) and installing a 10 kΩ resistor for another (R348) on the microcontroller PCB. Pin 7: RXD/EFC The default configuration uses this pin as an input for RS-232 data. Many system parameters (including the EFC, electronic frequency control) may be monitored via the RS-232 interface. The function of this pin may be changed to an analog monitor for the EFC by removing one resistor (R354) and installing a 10 kΩ resistor for another (R353) on the microcontroller PCB. Pin 5: 1PPS_IN/PHOTO The default configuration uses this pin as a 1pps input to allow time-tagging or phase locking to an external 1pps source. The function of this pin may be changed to allow monitoring of the amplified photo-signal. When configured as a 1PPS_IN, R241 will be omitted on the top PCB, and a 1 kΩ resistor will be installed for R242. When configured for PHOTO_AMP output, R242 will be omitted on the top PCB, and a 1 kΩ resistor will be installed for R241. 10 MHz coax shield The default configuration floats the shield of the 10 MHz coaxial connector with respect to ground. The 10 MHz output is transformer coupled, and the shield may be ground referenced by installing the jumper between J101 and J102 (located near the connector on the 10 MHz oscillator PCB.) Hardware Notes All of the pins on the interface connector are protected against continuous connection to any potential up to 24 Vdc. The power supply pins are protected against polarity reversal and may be operated up to +30 Vdc. In most applications, both +24 Vdc supplies (heater and electronic supplies) will be connected together and operated from a +24 Vdc supply. Logic outputs (LOCK/1PPS and TXD/PHOTO) have a 1 kΩ output resistance driven by a CMOS logic device operating between +5 Vdc and ground. Logic inputs (RXD/EFC and 1PPS_IN) have 100 kΩ to ground and 3.9 kΩ CMOS gate inputs (which have input protection diodes to +5 V and ground). RS-232 data is sent to the host on pin 4, received from the host on pin 7. The baud rate is fixed at 9600 baud, 8 bits, no parity, with 1 start and 1 stop bit. No DTR or CTS controls are used; rather, the XON/XOFF protocol has been implemented. The transmit drive level is 0 and 5 V, not the +/-12 V normally associated with RS-232. These levels are compatible with most RS-232 line receivers, but does not require their use (a TTL inverter may be used instead), hence simplifies the interface when used inside an instrument at the sacrifice of degraded noise immunity over long lines. PRS10 Rubidium Frequency Standard Applications 21 The PRS10 may be connected directly to a PC’s COM2: port with three wires: TXD, RXD, and ground. As the PRS10 sources only +5/0 V for the RS-232 (via 1 kΩ) the connecting cable should be kept short. PRS10 PC’s COM: (DB9 Connector) PC’s COM: (DB25 Connector) Pin 3 (TXD) Pin 2 (RXD) Pin 5 (GND) Pin 3 (TXD) Pin 2 (RXD) Pin 7 (GND) Pin 7 (RXD) Pin 4 (TXD) Pin 10 (GND) Operating Temperature The unit should be operated so that the baseplate temperature stays below +65 °C. This requirement is usually met by units operating on the bench at room temperature when powered by +24 Vdc. Frequency Adjustment A magnetic field coil inside the resonance cell is used to tune the hyperfine transition frequency. The magnetic field is controlled by a 12-bit DAC. The output frequency (at 10MHz) tunes quadratically with the DAC setting (0 ≤ DAC ≤ 4095), and ∆f(Hz) ≈ 5x10-9 x DAC2 . The DAC setting is changed from the nominal calibration value (see MO command) in various ways, including, calibration pot position, external calibration voltage, direct setting (see SF command), and external 1pps PLL control. When the unit is first turned on (or restarted), the internal frequency calibration pot position will be used to set the DAC relative to the calibration value stored in EEPROM. (If a voltage is applied to pin 2 of J100 (POT_W) then this voltage will override the pot position.) An SF command may be sent, or a 1pps input may be applied, to control the frequency offset directly. If either the SF command or the 1pps input control the frequency offset, then the pot position (or external control voltage) will not be used again until the power is cycled or the unit is restarted. All the various ways to adjust the frequency of the 10 MHz output are linearized, and they have a span of ±2000 x 10-12 or ±0.020 Hz. PRS10 Rubidium Frequency Standard 22 RS-232 Instruction Set RS-232 Instruction Set Syntax Commands consist of a two letter mnemonic and one or more parameters. Commands which end with a question mark (?) will return a value. Commands which end with an exclamation point (!) write the current parameter value to EEPROM for use after the next restart. Commands which end in an exclamation point and a question mark (!?) return the value stored in EEPROM. All data is communicated in ASCII codes. Commands are case insensitive, and spaces (ASCII 3210) are ignored. Commands are processed when a carriage return (ASCII1310) is received. Returned values are delimited with commas (in the case of multiple returned values) or a carriage return (in the case of a single or the last returned value). Commands available to the end user are in bold: some commands are for factory use only and a special code must be transmitted to enable these commands. Parameter lists are enclosed in curly brackets { }, the brackets are not part of the command. On reset, the unit will transmit the characters: PRS_10 with a carriage return. Initialization RS 1 Restart. This command will restart the PRS10’s microcontroller just like power-on. (It is not necessary to send a RS command on power-up.) All values will return to the values stored in EEPROM. (verbose mode disabled, 10 MHz set to last stored value, etc.) The frequency lock-loop will be disabled until the microcontroller verifies that the unit is warmed-up and that a useful signal level is present. Example: RS 1 will cause the unit to restart. VB{0 or 1} VB? Set verbose mode. The verbose mode is useful when a human is communicating with the PRS10 using a terminal program (the PRS10 will provide an “OK”, command prompts, etc.) The verbose mode should be disabled when a computer program is communicating with the PRS10 (where format characters would interfere.) Examples: VB0 disables the verbose mode (this is the power-on default mode.) VB1 will enable the verbose mode. ID? Identify. This command returns an identification string which includes the serial number and firmware version of the PRS10. Example: ID? will return the identification string PRS10_3.15_SN_12345 (model _firmware version_serial-number). PRS10 Rubidium Frequency Standard RS-232 Instruction Set 23 SN? SN{value} SN! SN!? Serial number. This command returns the unit’s serial number. Example: SN? will return 21567 for a unit with serial number 21567. The command to write and burn a serial number are for factory use only. ST? Status. This command will return a six number string corresponding to the values of the six status bytes. Each number will range between 0 and 255, and will be separated by commas. (For definitions of the status bytes, refer to the end of the detailed command descriptions.) LM{value} value = 0, 1, 2, or 3 LM? LM! LM!? Lock mode pin configuration. This command is used to configure the LOCK/1PPS output (pin 1 on the main connector, J100.) The LOCK/1PPS pin may be configured per the following table: LM 0 1 2 3 Description of LOCK/1pps Output Output goes low when locked to Rb, pulses high for 10 µs at 1 Hz 1pps locking pre-filter disabled Output goes low when locked to Rb, pulses high for 10 µs at 1 Hz 1pps locking pre-filter enabled (default) Output goes low when locked to Rb, 1pps is disabled Output goes high when locked to Rb, 1pps is disabled The default value is 1, so that pin 1 will go low when the unit is locked to rubidium, and will pulse high for 10 µs at a 1 Hz rate. The position of the 1pps pulse may be moved with the PP command. Example: LM? Could return 1, indicating that the unit is in its default configuration so that the lock pin goes low when locked to Rb, pulsing high for 10 µs at a 1 Hz rate. To configure the unit for no 1pps output, the command string LM 2 followed by LM ! will change the unit’s power on default for no 1pps output. PRS10 Rubidium Frequency Standard 24 RS-232 Instruction Set RC 1 RC! Recall. This command is used to return all values in EEPROM to the values which were present when the unit was first shipped from the factory (except for the unit-start and lampstart counters.) This command should be used if you have been writing values to EEPROM and have somehow corrupted the operation of the device. Executing this command may require calibration of the unit, as the frequency calibration values are also returned to their factory values. The unit will be restarted after the values in EEPROM have been restored to their factory values. Example: RC 1 will return all calibration values to the values which were determined for the unit when it was manufactured and restart the unit. The RC! command is a factory-only command which writes all of the current parameter values to the EEPROM. Frequency Lock-loop Parameters LO{value} value = 0 or 1 LO? Lock. This command can be used to stop the frequency lock-loop (FLL). It is essentially the same as setting the gain parameter to zero. It may be desirable in a particular application to stop the FLL and set the frequency control value for the 10MHz oscillator manually. (See the FC command.) Example: LO 0 will stop the FLL. LO? will return a value of 0 (if the FLL is not active) or 1 (if the FLL is active.) FC? FC{high,low} 0 ≤ high ≤ 4095 FC! FC!? 1024 ≤ low ≤ 3072 Frequency control. These commands allow direct control of the 22bit value which controls the frequency of the 10 MHz ovenized oscillator. Normally, this value is controlled by the FLL control algorithm, however, the FLL may be stopped, and the value adjusted manually. (See the LO command.) Two 12-bit DACs are scaled (by 1000:1) and summed to provide a varactor voltage which controls the frequency of the 10 MHz oscillator. The low DAC, which operates over half its range (to avoid FFL oscillations at the roll-over to the high DAC) provides a LSB frequency resolution of 1.5:10-12. The high DAC, which has a nominal value of 2048, has a LBS resolution of 1.5:10-9. These DACs provide a total tuning range of about ±3 ppm. Example: Suppose a unit’s FLL has been operating for some time and has settled. An FC? will return the current value of the DAC pair which might be 2021,1654. (Tracking the FC value over a long period of time tells you about the frequency variations of the 10MHz PRS10 Rubidium Frequency Standard RS-232 Instruction Set 25 crystal. The FC values will change to correct for variations in the crystal frequency due to aging and ambient conditions.) Both DACs may be set to any value in the range specified above. Example: FC 2048,2048 will set the 10MHz oscillator back to the middle of its tuning range. However, it is possible to set the frequency of the 10 MHz oscillator so far from the correct frequency that the FLL signal disappears, making the lock impossible. If this happens, the last saved FC value may be read from EEPROM with the FC!? command and restored with the FC{high,low} command. The FC! command is used to save the current FC values in the unit’s EEPROM. The FC!? Command may be used to read the value which is stored in the EEPROM. The value stored in EEPROM is used to set the 10 MHz at startup, before the FLL can be established. Occasionally while the unit is operating (at about 20 minutes after power-on and once a day there after) the program will write a new value to EEPROM to correct the value for crystal aging. Example: FC!? will return four values (separated by commas), the number of power cycles the unit has undergone, the number of times the FC pair has been written to EEPROM, and the value of the FC pair (high, low) which is used at turn-on and restart. DS? Detected signals. This command returns two numbers corresponding to the synchronously detected signals at the modulation frequency, ωmod, and at twice the modulation frequency, 2ωmod. The first number, the amplitude of the signal at ωmod, is the error signal in the rubidium frequency lock loop. The value is proportional to the instantaneous frequency error of the 10 MHz oscillator as detected by the physics package. The value may be large when the unit is first locking, and will bobble around zero in steady state. Each LSB corresponds to about 15 µVrms of signal at ωmod. The second number is the amplitude (in millivolts rms) of the synchronously detected signal at twice the modulation frequency, 2ωmod. The amplitude of this signal is proportional to the strength of the rubidium hyperfine transition signal. The returned value is a spot measurement taken over just one cycle of the modulation frequency. Since the signals have several Hz of equivalent noise bandwidth, they will be rather noisy. Example: DS? could return 55,800 indicating a small error signal and a strong resonance signal. PRS10 Rubidium Frequency Standard 26 RS-232 Instruction Set SF{value} -2000 ≤ value ≤ +2000 SF? Set frequency. This command is used to override the internal calibration pot (or external calibration voltage) to set the frequency directly, relative to the calibration values in EEPROM (see the SP and MO commands.) The command sets the frequency offset in units of parts in 10-12 (corresponding to a frequency resolution of 10 µHz at 10 MHz.) The SF? command will return the currently set relative frequency value (with a range of ±2000) whether the value comes from the internal calibration pot position, an external frequency control voltage, an SF command, or from the external 1pps phase lock loop control algorithm. However, SF set command is ignored if the unit is phase-locked to an external 1pps signal. (To re-establish direct control via the SF command, the PLL must be disabled. See PL 0 command.) Example: SF 100 will set the frequency 100 x 10-12 (or 0.001 Hz) above the stored calibration value, and the SF? command will return 100. Data from the SF command cannot be saved when the power is turned off. (To do this type of calibration, see the SP and MO commands.) Once executed, the SF command will disable the analog channels (internal calibration pot and external calibration voltage) until the power is cycled or the unit is restarted. SS? SS{value} 1000 ≤ value ≤ 1900 SS! SS!? Set slope. This command is used to read the slope calibration parameter for the SF command. This parameter compensates for a variety of factors which affect the magnitude of the coefficient between magnetic coil current and transition frequency. Example: SS? might return 1450, the nominal parameter value. This calibration parameter may not be altered by the end user. The (factory only) SS! command is used to store the current value of the SS parameter to the unit’s EEPROM. The SS!? will return the value of the SS parameter which is used on powerup or restart. GA? GA{value} 0≤ value ≤ 10 GA! GA!? Gain. This command sets the gain parameter in the frequency lock-loop algorithm. Higher gain values have shorter time constants, (the time constant is the time it takes for the frequency lock-loop to remove 67% of the frequency error) but have larger equivalent noise PRS10 Rubidium Frequency Standard RS-232 Instruction Set 27 bandwidths (which will reduce the short-term stability of the 10 MHz output.) A gain of 0 will stop the frequency lock-loop so that the frequency of the output is determined by the 10MHz ovenized oscillator alone. The gain setting, approximate time constants, and approximate equivalent noise bandwidths are detailed in the following table. The gain parameter is set automatically by the program, however, the user may want control over the parameter in special circumstances. Example: GA7 will set the gain parameter to 7, which has a time constant of about 2 s, which is a typical value for normal operation. GA? could return a value of 8 just after restart, which has a short time constant of about 1 s to assist the initial frequency locking. Setting the gain parameter during the first 6 minutes after turn-on or restart will abort the automatic gain sequencing. Command Time Constant (seconds) Noise Bandwidth (Hz) GA 0 GA 1 GA 2 GA 3 GA 4 GA 5 GA 6 GA 7 GA 8 GA 9 GA 10 Infinite 128 64 32 16 8 4 2 1 0.5 0.25 0 0.002 0.004 0.008 0.016 0.032 0.064 0.128 0.256 0.512 1.024 The GA! command stores the current value of the frequency lock loop gain parameter into the unit’s EEPROM. Example: If the current value of the gain is 6, the command GA! will write 6 to the unit’s EEPROM which will be used to initialize the gain parameter after the next power-on or restart. Then GA!? will return a 6. PH? PH{value} 0≤ value ≤ 31 PH! PH!? Phase. This command is used to set the phase of the synchronous detection algorithm. The frequency lock-loop (FLL) uses the in-phase component of the photo-signal at the modulation frequency (70 Hz) as the error signal for the FLL. The phase between modulation source and the error signal is affected by phase shifts in the modulation and signal filters and by optical pumping time constants. This parameter corrects for the accumulation of all of these phase shifts. Each modulation cycle consists of 32 phase slots, so each phase increment corresponds to 11.25°. Example: PH? would typically return a value of 24. PRS10 Rubidium Frequency Standard 28 RS-232 Instruction Set The PH! command is used to write the current phase parameter into the unit’s EEPROM. This is a factory only command. The value which is burned in EEPROM is used on power-on and restart, and may be queried by the PH!? command. Example: PH!? could return a typical value of 24. Frequency Synthesizer Control A frequency synthesizer, which uses the 10 MHz OCXO as a frequency reference, is used to generate the RF which sweeps the rubidium hyperfine transition. The frequency synthesizer multiplies the 10 MHz by a factor M = 19 * (64*N + A) / R, to generate a frequency near 6.834 GHz. (The factor of 19 is from frequency multiplication in the step recovery diode, and the other terms come from the operation of the dual modulus frequency synthesizer integrated circuit.) The apparent transition frequency is different for each physics package, due mostly to variations in the fill pressure of the resonance cell. The frequency synthesizer parameters, R, N and A, are used to adjust the frequency synthesizer’s output frequency to the closest frequency just above the apparent transition frequency, then the magnetic field is set to move the transition frequency up to the synthesizer frequency. During frequency locking, the frequency of the 10 MHz OCXO is adjusted to maintain the output of the frequency synthesizer on the rubidium hyperfine transition frequency. Initial calibration of the unit will involve finding the synthesizer parameters and magnetic field value which will lock the 10 MHz OCXO at exactly 10 MHz. During the lifetime of the unit, there will be some aging of the physics package, which will cause the apparent transition frequency to change. This is usually corrected by minor calibration adjustments of the magnetic field strength, which provides a setting resolution of a few parts in 10-12. (See the MO command.) However, if the magnetic field strength reaches its lower or upper limit, it is necessary to change the frequency synthesizer parameters, which can change the output frequency in steps of about one part in 10-9. The table in Appendix A details the values for R, N and A for the range of frequencies needed. SP? SP {R,N,A} 1500≤ R ≤ 8191 800≤ N ≤ 4095 0≤ A ≤ 63 SP! SP!? Set Parameters. This command is used to set or query the frequency synthesizer’s parameters, which will coarsely adjust the unit’s output frequency. These parameters may need to be adjusted if the unit cannot be calibrated by magnetic field adjustment. PRS10 Rubidium Frequency Standard RS-232 Instruction Set 29 Example: During calibration, a unit’s 10 MHz output frequency is found to be low by 0.010 Hz, and the magnetic field offset adjustment is already at its maximum. (See the MO command.) Sending the SP? command returns the current values of R, N and A which are 2610,1466,63 in this example. This corresponds to line 38 in the table in Appendix A. To increase the frequency of the 10 MHz output, we select the next higher setting, line 37, which will increase the frequency by 0.01986 Hz. To do this, we send the command SP 5363,3014,22 (which are the parameters from line 37). Waiting for the frequency to settle, we now measure the output to be about 0.0098 Hz high. Now the magnetic field is adjusted down to calibrate the unit to exactly 10 MHz. (The SP! command is used to save these new values in EEPROM for the next power-on or restart. Also see the MO command for adjusting the magnetic field.) The SP! command is used to write the current frequency synthesizer parameters to the unit’s EEPROM for use after the nest restart or power-on cycle. This command is used after the SP command is used during the calibration of the unit. Example: SP! will write the frequency synthesizer parameters (R, N and A) which are currently in use to the unit’s EEPROM. SP!? will return the values for R, N and A which are currently in the unit’s EEPROM. The SP!? command may be used to verify that the SP! write command executed correctly. Magnetic field Control A magnetic field coil inside the resonance cell is used to tune the apparent hyperfine transition frequency. The magnetic field is controlled by a 12-bit DAC. Increasing the magnetic field will increase the hyperfine transition frequency, which will increase the frequency of the 10 MHz output. The transition frequency may be tuned over about ±3 x 10-9 by the magnetic field, which corresponds to ±0.030 Hz at 10 MHz. The output frequency (at 10 MHz) tunes quadratically with field strength, and ∆f(Hz) ≈ 0.08 * (DAC/4096) 2 . A minimum magnetic field should always be present to avoid locking to the wrong Zeeman component of the hyperfine transition, so the 12-bit DAC may be set from 1000 to 4095 with 3000 being the nominal midscale value. (A DAC value of 1000 corresponds to about 6% of the full-scale frequency tuning range, 3000 corresponds to about 53%, while 4095 is 100% of the full-scale range.) To help cancel frequency shifts due to external magnetic fields, the current in the coil is switched at a 5 Hz rate. The frequency lock-loop averages over a full period of the switch rate to avoid injecting a spur at 5 Hz onto the 10 MHz control signal. The switching of the magnetic field is enabled at power-on and restart, but may be turned on or off by RS-232 command. (see MS command.) The commands associated with magnetic field control (MO, MS, and MR) allow direct control of the magnetic field circuitry. Most users will not want to control the magnetic field directly, but will instead allow the program to read the frequency calibration pot or external control voltage and then control the magnetic field. If they want software control of the unit’s PRS10 Rubidium Frequency Standard 30 RS-232 Instruction Set calibration, they may choose to use the SF commands, which disable the analog control and allow the frequency to be adjusted over a range of ±2000x10-12. (The program will linearize the magnetic field control of the frequency offset with either analog or software control.) MS? MS{0 or 1} Magnetic switching. The MS command is used to turn off or on the 5Hz switching of the frequency tuning magnetic field. Magnetic switching is enabled when the unit is powered-on or after a restart. (Since the PRS10 is calibrated with the field switching enabled, turning off the field switching may alter the calibration.) Example: MS 1 will turn on the magnetic field switching, and MS 0 will turn it off. MS? will return a “1” if the field switching is currently enabled. MO? MO{value} MO! MO!? 2300 ≤ value ≤ 3600 Magnetic offset. The magnetic offset is the value, determined when the unit is calibrated, which calibrates the unit to 10 MHz. The restricted range is necessary to allow room for user calibration via the internal frequency calibration pot or by an external voltage. If the unit cannot be calibrated to 10 MHz within the allowed range of MO values, then a different setting for the frequency synthesizer is required. (See SP command and the table in Appendix A. Example: MO 3000 sets the magnetic offset to 3000, which is its nominal (mid-linear scale) value. The MO? command reads back the current value of the magnetic offset. MO! is used to store the current value of the magnetic offset parameter to EEPROM for use after the next restart. MO!? may be used to query the value stored in EEPROM. This value is used on power-up or restarts. MR? Magnetic read. This command returns the value that the 12-bit DAC is using to control the magnetic field. This value is computed from the magnetic offset value (see MO command) and the position of the internal frequency calibration pot, external calibration voltage, or value sent by the SF command. The value is computed from the equation DAC = √(SF*SLOPE + MO2) where SF is the desired frequency offset in parts per 10-12 (from the cal pot position, the SF command, or the 1pps PLL and is in the range –2000 < SF < 2000), SLOPE is the SF calibration factor with a nominal value of 1450 (see SS command), and MO is the magnetic offset value. The returned value should be in the range of 1000 to 4095. PRS10 Rubidium Frequency Standard RS-232 Instruction Set 31 Example: MR? would return a value of 3450 if the magnetic offset is at 3000, the SF command requested an offset of +2000 x 10-12, and the SS CAL factor has the nominal value of 1450. Frequency Control The frequency of the 10 MHz output may be adjusted in a number of ways: the internal calibration potentiometer may be set (accessible via a hole in the bottom plate), an external voltage (0 to +5.00 Vdc, applied to the interface connector pin 2) can override the internal pot, or, these analog channels may be overridden with a software command which sets the frequency directly. When the unit turns on, or after a restart command, the control program will default to reading the analog channel for frequency calibration. (This is important to maintain compatibility with existing sockets.) The calibration pot and the external voltage control provide a full-scale tuning range of ± 2000 x 10-12, with a worst case resolution of 5 x 10-12. All of the channels for calibrating the unit are linearized, so that the frequency characteristic will be linear with applied voltage, pot setting, or SF value even though the transition frequency changes quadratically with field strength. One pulse per second (1pps) control To facilitate system integration, the PRS10 provides a 1pps output which may be set over an interval from 0 to 999,999,999 ns with 1ns resolution. The unit also has the ability to measure the arrival time of a 1pps input over the same interval and with the same resolution. The ability to time-tag a 1pps input allows the PRS10 to be phase-locked to other clock sources (such as the 1pps output from a GPS receiver) with very long time-constants. This is a very useful feature for network synchronization, and allows the configuration of a reliable Stratum I source at a very low cost. TT? Time-tag. This command returns the value of the most recent time-tag result in units of nanoseconds. If a new time-tag value is not available then -1 (the only case for which the returned value is negative) will be returned. Example: TT? would return the value 123456789 to indicate that the most recent 1pps input arrived 123,456,789ns after the 1pps output. Returned values range from 0 to 999999999. PRS10 Rubidium Frequency Standard 32 RS-232 Instruction Set TS? TS{value} 7000 ≤ value ≤ 25000 TS! TS!? Time slope. This command is used to calibrate the analog portion of the time-tagging circuit. The analog portion is used to digitize the time of arrival with 1 ns resolution and 400 ns fullscale. (Counters are used for the portion of a time interval longer than 400 ns.) The analog circuit stretches the time interval between the 1pps input and the next edge of a internal 2.5 MHz clock by a factor of about 2000, and measures the duration of the stretched pulse by counting a 2.5 MHz clock. The analog portion of the time-tag result is calculated from the equation ∆T(ns) = counts * TS / 216, where TS is the time slope value, which has a nominal value of 13,107. Example: TS? might return 14,158 which is a time slope parameter value a bit above the nominal value, which would be required if the analog portion of the time-tagging circuit stretched the pulse by a bit less than a factor of 2000. TS? will return the current value of the time slope. The TS! command is used to write the current value of the time slope parameter into the unit’s EEPROM. The TS {value} and TS! are factory only commands. Example: TS! will write the current value of the time slope (which may be queried with the TS? command) to the unit’s EEPROM. TS!? will return the time slope calibration factor which is in the unit’s EEPROM. TO? TO{value} TO! TO!? -32767 ≤ value ≤ 32768 Time offset. This calibration value (in ns) is added to the measured time-tag value to reference the result to the 1pps output. To calibrate, the 1pps output is connected to the 1pps input and the time-tag is read with the TT? command. The returned value is subtracted from the current TO value and sent with the TO command to calibrate the offset. Example: Suppose: the 1pps output is connected to the 1pps input. A time tag value, read with the TT? query, returns a value of 25ns. The TO parameter, read via the TO? query, returns a value of -1750ns. The command TO -1775 is sent to correct for the offset. After waiting about one second (to allow another time-tag value to be acquired) the next TT? query returns a value of 2ns (indicating a measurement of 2ns after the 1pps output) Waiting another second, the next TT? query returns the value 999,999,999ns (indicating 1 ns before the 1pps output). These values are consistent with a well calibrated time-tag offset. Following calibration of the TO parameter, the TO! command is used to write the current value of the time offset to the unit’s EEPROM. Example: TO! will write the current time-tag PRS10 Rubidium Frequency Standard RS-232 Instruction Set 33 offset value to the unit’s EEPROM for use after the next power-up cycle or restart command. TO!? will return the value which is burned in the unit’s EEPROM. (Note: Firmware revisions prior to Rev 3.23 do not allow user TO! commands. Check the firmware revision with the ID? command. PP{value} 0 ≤ value ≤ 999999999 Place pulse. This command is used to move the 1pps output from its current position. The 1pps output can be moved earlier in time by 1 ns to 999999999 ns. Since the 1pps input timetag is referenced to the 1pps output, changing the 1pps output placement will change the report time-tag values as well. (See the TT and TO commands.) Example: PP 123456789 will move the 1pps pulse train earlier by 123,456,789 ns. PS? PS{value} PS! PS!? 100 ≤ value ≤ 255 Pulse slope calibration. This command is used to calibrate the analog portion of the 1pps output time delay circuit. This circuit is used to delay the 1pps pulse train with 1 ns resolution and 100 ns full-scale. (Counting logic is used for the portion of the time interval longer than 100 ns.) The pulse slope value corresponds to the DAC8 value which provides a delay closest to (but not exceeding) 100 ns. Example: PS 200 set the pulse slope to its nominal value of 200. (PS{value} is a factory only command.) The PS? command will return the current value of the pulse slope. The PS! command writes the current value of the pulse slope to the unit’s EEPROM for use after the next power-on or restart. This command is used after the pulse output analog output is calibrated. Example: PS! will write the current value of the pulse slope (which calibrates the 100 ns analog delay portion of the 1pps pulse delay circuit) to the unit’s EEPROM. Note that PS! is a factory-only command. 1PPS Locking Control To facilitate integration into systems which require very low aging, automatic calibration, or a traceable frequency standard, the PRS10 may be locked to an external 1pps input. A second-order digital PLL is used to lock the unit’s frequency (both the 10 MHz and 1pps outputs) to an external 1pps input with time constants ranging from 256 s to 65536s (about 4 minutes to about 18 hours). When provided with an accurate and stable 1pps source, the unit will automatically align its 1pps output to the 1pps input and then adjust the frequency of the rubidium reference to PRS10 Rubidium Frequency Standard 34 RS-232 Instruction Set maintain the alignment over time. A typical application would lock the PRS10 to the 1pps output from a GPS receiver with a time constant of several hours. Several commands and one status byte may be used to control and monitor the PLL, however, default values will allow units to lock to clean 1pps inputs without any software interaction. PL? PL{0 or 1} PL! PL!? Phase lock control. This command may be used to disable the 1pps PLL, or to re-enable (and so restart) the 1pps PLL. The unit is shipped with the phase lock control enabled. This command would be used if the 1pps time-tagging were being used to measure the position of 1pps inputs and phase locking is not desired. Example: PL 0 will disable the PLL to the 1pps inputs so that the frequency of the rubidium standard will not be affected by the 1pps inputs. PL? will return a “1” if the PLL to the 1pps is enabled. PL! is used to write the current value (0 or 1) to the EEPROM for use after the next start up. PL!? is used to query the value of the phase lock control parameter which is stored in the unit’s EEPROM. PT? PT{value} PT! PT!? 0 ≤ value ≤ 14 ; τ1 = 2(value+8) seconds (256, 512, ... 4,194,304) Phase-lock integrator time constant. This command is used to set the PLL’s integrator’s time constant, τ1, which phase-locks the PRS10 to an external 1pps input. The integrator time constant is equal to 2(value+8) seconds. The default value is 8, which provides an integrator time constant of 2(8+8) or 65536 seconds. Integrator’s time constants can range from 256 to 4,194,304 seconds, or from about 4 minutes to 18 days. It is important to note that the natural time constant, τn, is different from the integrator time constant, as shown in the table below. The natural time constant is the best measure of the loop response. The PLL natural time constant spans between 8 minutes and 18 hours for PT values between 0 and 14. Example: PT10 sets the integrator time constant to 2(10+8) seconds, or about 72 hours. (Refer to Table below.) For PT10 the natural time constant is about 4.5 hours. PT? will return the current value of the time constant parameter. A phase lock time constant may be stored in EEPROM as a new default with the PT! command. The PT!? command may be used to verify the value stored in EEPROM. The following case will illustrate the operation of the PLL: Suppose that the PRS10 has been phase locked to a stable 1pps reference for a very long time (several periods of τn) when the 1pps reference input makes an abrupt shift of +100ns (moving later in time). The PRS10’s 1pps PLL algorithm will reduce the PRS10’s frequency of operation (by adjusting its SF PRS10 Rubidium Frequency Standard RS-232 Instruction Set 35 parameter) to eliminate the 100ns phase shift between the 1pps reference input and the 1pps output. After the phase shift is eliminated, the PRS10 will settle to the “correct” operating frequency. The PLL algorithm computes integral and proportional terms from time-tag measurements, adjusting the SF parameter to phase lock the 1pps output to the 1pps input. The table below shows the integral and proportional gain terms. For the nominal PT value of 8, the integral term is -0.055 SF bits per hour per ns of time-tag and the proportional gain is -0.25 SF bits per ns of time-tag. Per the table below for PT8, if the input reference shifts by +100ns, the proportional term will adjust the SF by -0.25bits/ns * 100ns = -25 bits. Each SF bit corresponds to 1:10-12 of the operating frequency, and so the PRS10 frequency will be shifted by about -25 x 10-12. The integral term will begin ramping by (-0.055bits/hour/ns) * 100ns, or by -5.5 bits per hour. The phase shift between the 1pps input and 1pps output will be gradually eliminated. (Phase jumps of 100ns are quite common on 1pps outputs from GPS receivers, which are a likely 1pps reference to the PRS10. The corresponding frequency jumps of 25 x 10-12 may be excessive in some applications, and so a digital pre-filter is used to smooth the time-tag values before they are used by the PLL algorithm. See LM command.) PLL Table for all PT values, assuming a stability factor, ζ=1. PT Parameter Integrator TimeConstant Integral Gain Proportional Gain Natural TimeConstant Parameter set by PT command (hours) (SF bits per hour per ns of time-tag) (SF bits per ns of time-tag) Characterizes PLL response (hours) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 0.07 0.14 0.28 0.57 1.14 2.28 4.55 9.10 18.20 36.41 72.82 145.64 291.27 582.54 1,165.08 -14.063 -7.031 -3.516 -1.758 -0.879 -0.439 -0.220 -0.110 -0.055 -0.027 -0.014 -0.007 -0.003 -0.002 -0.001 -3.95 -2.80 -1.98 -1.40 -0.99 -0.70 -0.49 -0.35 -0.25 -0.17 -0.12 -0.09 -0.06 -0.04 -0.03 0.14 0.20 0.28 0.40 0.56 0.80 1.12 1.59 2.25 3.18 4.50 6.36 8.99 12.72 17.99 PRS10 Rubidium Frequency Standard 36 RS-232 Instruction Set PF? PF{value} PF! PF!? 0 ≤ value ≤ 4 ; (value:ζ) : (0:1/4, 1:1/2, 2:1, 3:2, or 4:4) Phase-lock stability factor. This command is used to set the stability factor, ζ, of the 1pps PLL. The stability factor is equal to 2(value-2). The default value is 2, which provides a stability factor of 2(2-2) = 20 = 1. Stability factors can range from 0.25 to 4.0. Example: PF 1 sets the stability factor to 0.5, which will reduce the equivalent noise bandwidth of the PLL at the cost of increasing the ringing near the natural frequency (relative to the default settings). PF? will return the current value of the stability factor parameter. PF! may be used to write the current stability factor to the EEPROM for use as the new default. PF!? may be used to read the value of the stability factor which is stored in EEPROM. PI? PI {value} -2000 ≤ value ≤ 2000 Phase-lock integrator. This command is used to set the value of the integral term in the PLL’s digital filter. It is not necessary to set this value, as it will be initialized by the PLL routine to the current frequency setting parameter when the PLL begins. Users may want access to the value to alter the PLL characteristics, or to investigate its operation. Example: PI 0 will set the integrator in the PLL’s digital filter to 0, which is the center of the ±2000 bit range. PI? will return the current value of the PLL integrator. (There are two terms which control the phase locking of the PRS10 to an external 1pps source: the integral term and the proportional term. The proportional term is equal to the value returned by an SF? minus the value returned by the PI?.) Analog Control SD{port}? SD{port,value} 0 ≤ port ≤ 7 and 0 ≤ value ≤ 255 (factory only) SD{port}! SD{port}!? Set DAC. This command is used to set (or read the settings of) an octal 8bit DAC which provides analog signals to control systems parameters. The command which sets values is only available to the factory. The command to query values may be used by all. The query command returns a single integer in the range of 0 to 255. Port 0 1 Function Controls the amplitude of the RF to multiplier in resonance cell Controls the analog portion (0 to 99 ns) of the delay for the 1pps output PRS10 Rubidium Frequency Standard RS-232 Instruction Set 2 3 4 5 6 7 37 Controls the drain voltage for the discharge lamp’s FET oscillator Controls the temperature of the discharge lamp Controls the temperature of the 10 MHz SC-cut crystal Controls the temperature of the resonance cell Controls the amplitude of the 10 MHz oscillator Controls the peak deviation for the RF phase modulation Example: SD2? could return the value 255 indicating that the unit has set the discharge lamp’s FET drain voltage to the maximum (which it does while it is trying to start the lamp.) The SD{port}! is a factory only command which writes the data from the corresponding SD port to the unit’s EEPROM for use on subsequent restarts. Example: SD3!? will return the start-up value for SD3 (lamp temperature control value) which is stored in the unit’s EEPROM. Analog Test Voltages AD{port}? port = 0,1,2,...15 Analog to digital. This command reads the voltage at the corresponding 12-bit ADC port and returns the voltage as a floating point number. Values can range from 0.000 to 4.998. The voltages correspond to various test points in the system per the following table. Note that this command can only query. Examples: AD10? could return the value 0.710 indicating that the case temperature sensor is at 71 °C (this sensor indicates a temperature which is about midway between the baseplate temperature and the lamp temperature.) Command Returned voltage AD 0? AD 1? AD 2? AD 3? AD 4? AD 5? AD 6? AD 7? AD 8? AD 9? AD 10? AD 11? AD 12? AD 13? AD 14? AD 15? Spare (J204) +24V(heater supply) divided by 10. +24V(electronics supply) divided by 10 Drain voltage to lamp FET divided by 10 Gate voltage to lamp FET divided by 10 Crystal heater control voltage Resonance cell heater control voltage Discharge lamp heater control voltage Amplified ac photosignal Photocell’s I/V converter voltage divided by 4 Case temperature (10 mV/°C) Crystal thermistors Cell thermistors Lamp thermistors Frequency calibration pot / external calibration voltage Analog ground PRS10 Rubidium Frequency Standard 38 RS-232 Instruction Set AD{port}? 16 ≤ port ≤ 19 A/D via CPU’s E-port. This command returns a value corresponding to the voltage present at the input to the microcontroller’s octal 8bit ADC (port E on the MC68HC11). Only the first four ports are in use. The voltage corresponds to various test point in the system per the following table. Example: AD17? could return a value of 4.81 indicating that the 360 MHz RF synthesizer has acquired lock. Command AD 16? AD 17? AD 18? AD 19? Returned voltage Varactor voltage for 22.48 MHz VCXO (inside RF synthesizer) / 4 Varactor voltage for 360 MHz VCO (output of RF synthesizer) / 4 Gain control voltage for amplifier which drives frequency multiplier / 4 RF synthesizer’s lock indicator voltage (nominally 4.8 V when locked ) Status Bytes ST? Status query. This command returns the six system status bytes which are used to indicate the health and status of the unit. The values ranges from 0 to 255. The six status bytes are detailed in the tables below. A status bit will remained set until it is read, even though the condition which caused the error has been removed. Some status bits are not errors: for example, during warmup the status bytes may indicate that the lamp is not lit, temperatures are low, and the unit is not locked. Example: Immediately after power is applied to a unit, the command ST? returns 16, 3, 21, 1, 2, 129. From the status byte definitions below, we see that the following conditions exist: 16… 3… 21… 1… 2… 129.. the lamp has not yet started the RF VCXO has not yet locked the lamp, crystal, and cells are all below their set point temperatures the frequency lock has not been established fewer than 256 1pps inputs have been qualified both the lamp and unit have been restarted ST1 : Power supplies and Discharge Lamp ST1 bit 0 1 2 Condition which sets bit Corrective Action +24 for electronic < +22 Vdc +24 for electronics > +30 Vdc +24 for heaters <+22 Vdc Increase supply voltage Decrease supply voltage Increase supply voltage PRS10 Rubidium Frequency Standard RS-232 Instruction Set 3 4 5 6 7 +24 for heaters > +30 Vdc Lamp light level too low Lamp light level too high Gate voltage too low Gate voltage too high 39 Decrease supply voltage Wait: check SD2 setting Check SD2 setting Wait: check SD2 setting Check SD2 setting ST2: RF Synthesizer ST2 bit 0 1 2 3 4 5 6 7 Condition which sets bit Corrective Action RF synthesizer PLL unlocked RF crystal varactor too low RF crystal varactor too high RF VCO control too low RF VCO control too high RF AGC control too low RF AGC control too high Bad PLL parameter Query SP? verify values Query SP? verify values Query SP? verify values Query SP? verify values Query SP? verify values Check SD0? values Check SD0? values Query SP? verify values ST3: Temperature Controllers ST3 bit 0 1 2 3 4 5 6 7 Condition which sets bit Corrective Action Lamp temp below set point Lamp temp above set point Crystal temp below set point Crystal temp above set point Cell temp below set point Cell temp above set point Case temperature too low Case temperature too high Wait for warm-up Check SD3, ambient Wait for warm-up Check SD4, ambient Wait for warm-up Check SD5, ambient Wait for warm-up Reduce ambient ST4: Frequency Lock-Loop Control ST4 bit 0 1 2 3 Condition which sets bit Corrective Action Frequency lock control is off Frequency lock is disabled 10 MHz EFC is too high 10 MHz EFC is too low Wait for warm-up Enable w/LO1 command SD4,SP,10MHz cal,Tamb SP, 10 MHz cal PRS10 Rubidium Frequency Standard 40 RS-232 Instruction Set 4 5 6 7 Analog cal voltage > 4.9 V Analog cal voltage < 0.1 Int cal. pot, ext cal. volt Int cal. pot, ext cal. volt ST5: Frequency Lock to External 1pps ST5 bit 0 1 2 3 4 5 6 7 Condition which sets bit Corrective Action PLL disabled < 256 good 1pps inputs PLL active > 256 bad 1pps inputs Excessive time interval PLL restarted f control saturated No 1pps input Send PL 1 to enable Provide stable 1pps inputs ST6: System Level Events ST6 bit 0 1 2 3 4 5 6 7 Condition which sets bit Lamp restart Watchdog time-out and reset Bad interrupt vector EEPROM write failure EEPROM data corruption Bad command syntax Bad command parameter Unit has been reset PRS10 Rubidium Frequency Standard Provide stable 1pps inputs Provide accurate 1pps Provide stable 1pps inputs Wait, check 1pps inputs Provide 1pps input PRS10 Calibration Procedures 41 Calibration Procedures Many applications for the PRS10 only require that the frequency of the 10 MHz output be calibrated. This may be done by adjusting a potentiometer, which is accessible through a hole in the bottom of the unit. The unit should be operating for at least 24 hours before it is calibrated. The 15 turn pot has a range of ±0.020 Hz. The frequency increases if the pot is turned clockwise, by about 0.001 Hz for 3/8’s of a turn. Note: the potentiometer position will not affect the frequency of operation if : (1) it is turned to either extreme, (2) an external control voltage is applied to pin 2 of the main connector, J100, (3) an SF (set frequency) command has been sent via the RS-232 interface, or, (4) the unit is locked to an external 1pps input. The time constant for pot adjustments depend on the setting of the frequency lock-loop gain (see GA command: the default is about 2 seconds.) In the case that the unit cannot be calibrated because the internal pot has reached an extreme position, it will be necessary to modify a calibration values which are stored in the unit’s EEPROM. To verify that the pot has been turned to a limit of its motion, measure the voltage on pin 2 (POT_W) of J100 (the main connector) with respect to the chassis. Zero volts on pin 2 indicates that the pot has been adjusted for the lowest frequency, and +5.0 Vdc indicates that the pot has been adjusted for the highest frequency. To modify EEPROM calibration values, it will be necessary to establish RS-232 communications with the PRS10. This can be done with a three wire connection between the PC COM: port and the PRS10’s main connector. A communication program (see Windows Accessories or other) will be needed as well. (See MO and SP commands.) PRS10 Rubidium Frequency Standard 42 Circuit Descriptions Circuit Descriptions Schematic RB_F1 (sheet 1 of 6) Components shown on this schematic are located on the vertical PCB which holds the main connector to the outside. This board has a 10MHz SC-cut ovenized oscillator which is frequency locked by the microprocessor to the hyperfine transition in rubidium via a high resolution DAC. This will overcome two important shortcomings of the oscillator circuit: frequency aging of a few parts in 10-10/day , and a sensitivity of a few parts in 10-9 over the ambient temperature range of 0°C to 65°C. Input Power D101 and D102 (MBRD660CT Schottky diodes in DPAKs) protect the unit from input power supply polarity reversals on +24_CLEAN and +24_HEAT. The supplies are filtered by L104 and L105 (ferrite beads with about 3µH and Q=15 at 100kHz) and C115 and C116. These filters are designed to reduce EMI emission and susceptibility but they have a low Q resonance at about 40kHz. Voltage Reference U100 provides a 10.00V low noise reference for the entire unit and various biases for the crystal oscillator. The reference voltage is divided by two and buffered by U102B to provide a +5.00V reference for the internal calibration pot and for the POT+ output. Crystal Oscillator The crystal oscillator uses a Colpitts configuration. The 3rd overtone SC-cut crystal is specified to operate at 10.0MHz with a series load of 20pF. (Hence the crystal will operate slightly above its series resonance to contribute an inductive reactance equal in magnitude to the series capacitive reactance.) At 10MHz, the network L100, L101 and C102 has a capacitive reactance equivalent to an 87pF capacitor. At the fundamental (3.3MHz) and at the B-mode frequency (10.8MHz) this network is inductive, and so there will be no gain provided by Q100. In addition to this network, C103, C104, the varactor D100, and C106 (which connects to the ac ground at the emitter of Q101) are all in series with the crystal. C104 is selected when the unit is calibrated so that the crystal will operate at 10.0MHz with the nominal EFC voltage applied to the varactor. The crystal frequency tunes linearly with the net series reactance, with a tuning coefficient of -1Hz/20Ω. Series capacitors tune the crystal to higher frequencies, series inductors tune the crystal to lower frequencies. Only NPO capacitors are to be used and inductors should be either air or iron powder core (no ferrites) in order to preserve the relative insensitivity to ambient temperature variations. To move the oscillator to higher frequencies, C(pF)=808/∆f(Hz). To move the oscillator to lower frequencies, L(µH)=0.29∆f(Hz). PRS10 Rubidium Frequency Standard Circuit Descriptions 43 The MMBV609 varactor provides an approximate linear tuning characteristic over ±2 ppm. This will allow the unit to correct for aging of the crystal for a nominal 27 year life, given a daily aging of 2 parts in 10-10. The crystal is operated at its temperature plateau of about 80°C. (The plateau temperature is determined at calibration for each unit. ) The frequency is a maximum at the plateau and so the oscillator will typically be a few hundred Hertz low when the unit is turned on at room temperature. Near the plateau top, the frequency deviation verses temperature is about ∆f(Hz) = -0.061x ∆T(°C)2. Note that if the crystal oven were to lose regulation by 12.8°C (perhaps the baseplate is too hot) that this would cause a 1ppm frequency error, which could be corrected by the Rb frequency lock loop. Power to overcome losses (to sustain oscillation) is provided by Q100. The dominate loss is the series resistance of the crystal (about 80Ω). Q100 provides power by injecting a current at the top of L100 which is in phase with the 10MHz voltage at this node. The amount of current injected depends on the size of C103 and R103: the current injected is equal to the ac voltage across C103 divided by the resistance of R103 (assuming emitter following action of Q100). The magnitude of the oscillation will grow until the peak voltage at the base exceeds the collector voltage, causing Q100 to saturate. The circuit is designed to allow about 1mA(rms) to circulate through the crystal. The ac current is high enough to provide low phase noise, but low enough to minimize aging. This ac current is cascoded to the inverting input of the high speed op-amp, U101, by Q101. Q101 provides a good ac ground for the crystal circuit (to maintain high in-circuit Q). With an emitter current of 4mA the emitter resistance of Q101 will be about 6Ω. Q101 also helps to isolate the crystal circuit from variations from the external 10MHz load (as does U101) so that the frequency of operation of the circuit will not be pulled by the load. The op-amp operates as a transconductance amplifier with a transconductance gain of about 2000Ω at 10MHz. The dc output of the op-amp is midway between the supplies (at about 8.25Vdc), which is controlled by the current drawn by Q101 and the value of R111. There is a 10Vpp sine at 10MHz at the output which is ac coupled, reverse terminated, and matched to a 50Ω load by C111, R114, and T100. The primary of T100 is tuned to 10MHz, so that spurs and harmonics are attenuated. The 7:2 turns ratio transforms the 50Ω into a 612Ω load at 10MHz. The output amplitude into 50Ω is 0.50Vrms (1.414Vpp or +7dBm). Extremely low phase noise is an important specification for this oscillator. The phase noise close to carrier (10Hz offset and below) is dominated by 1/f components, including, crystal parameters, temperature stabilization, amplitude limiting, and gain mixing. Far away from carrier (>1kHz) the noise floor is determined by ratio of broadband noise sources to the signal current at 10MHz. Examples of broadband sources include the shot noise current on base currents, the Johnson noise current from bias resistors, and the op-amp’s input current and voltage noise. It is also important to maintain very low noise on the EFC and amplitude PRS10 Rubidium Frequency Standard 44 Circuit Descriptions control signals. Typical phase noise is -125dBc/Hz @ 10Hz, -145dBc/Hz @ 100Hz, and 155dBc/Hz @ >1kHz. Circuit elements and operating points were chosen to reduce noise sources. An SC-cut resonator was chosen for high Q and stable motional impedances. The transistors are operated at a few mA, trading off base bias current noise against emitter resistance. Metal film resistors are used to reduce 1/f noise. Series 100µH inductors are used to reduce the Johnson noise current of bias resistors. The op-amp was chosen for low input current noise, and it is operated with sufficient gain so that its voltage noise would not degrade the phase noise floor. Finally, the crystal is operated at its plateau temperature to reduce the frequency instability associated with temperature fluctuations. Crystal Heater The crystal heater has the same design as the two other heaters (resonance cell and lamp) in the system. There are two heaters in TO-220 packages: an LM340-12 (a +12Vdc voltage regulator) and a TIP107 (a pnp power Darlington). The tabs of both TO-220 heaters are at ground, so they are bolted directly to the block. All of the heater current passes through three parallel 1Ω shunt resistors to sense current. The block temperature is sensed by two series 100kΩ thermistors, which are directly beneath the TO-220 heaters in the oven block. (Two sensors are used because the division of power will depend on the heater voltage applied to the unit.) At the operating temperature of 75°C, each thermistor will have a resistance of about 15kΩ. The control circuit will allow operation up to 90°C. (For the lamp, the nominal operating temperature is 105°C, for which each thermistor will have a resistance of about 5.5kΩ. The maximum setpoint for the lamp is 122°C.) The control circuits for all of the heaters are on the top (analog) PCB. The control circuit can vary the heater current from 0 to 0.7A to maintain the set point. In the case of a control failure, the LM340-12 will turn off the current if the junction temperature reaches 125°C. Schematic RB_F2 (Sheet 2 of 6) The components contained on this schematic are all located on the top (analog) PCB. This board contains most of the analog circuitry for the system, including, temperature servos, photodiode amplifier and filter, analog signal multiplexers, and noise filters for the crystal’s EFC and amplitude control signals. Temperature Control Servos There are three temperature control servos (for the crystal oven, the Rb discharge lamp, and the Rb resonance cell). The three servos are identical except for the maximum set point (122°C for the lamp, and 90°C for the others.) The circuit description will refer to the crystal temperature controller. PRS10 Rubidium Frequency Standard Circuit Descriptions 45 The controller is a proportional-integral controller. The output of the error amplifier (U200A) is used to control the current flowing in the heater circuit, with a range from 0 to 500mA (to provide heater powers from 0 to 12W). The error amplifier has a proportional gain of (R205/R204)+1=6.5 and an integration time constant of R204xC201=1 s for the signal at its non-inverting input. The inverting input is biased near 1.00Vdc, so that the servo will try to maintain the temperature so that there is 1.00Vdc on the thermistors. For a set point of 75°C the series thermistor pair will have a resistance of 30kΩ. To get 1.00Vdc at the non-inverting input of U200A, XTAL_SET is set to 170 bits (full-scale of 4V/255=0.01568V/bit, so 170 bits=2.66Vdc). After settling, a LSB step in XTAL_SET (15.6mV) will become about 5.8mV at the oninverting input, and cause an immediate change of 2x5.8mV = 11.6mV at the output of U200A, followed by a ramp of 5.8mV per second. This quickly increases the power by about 0.27W, then by 0.14W/S thereafter. The servo will settle when the thermistors heat-up, decreasing their resistance, so that the voltage at the non-inverting input returns to 1.00Vdc. The thermistor resistance decreases by about 3%/°C. An LSB increase in XTAL_SET near the nominal 2.66Vdc will cause the current to increase by .0156/(2.66-1.00) or about 0.9%. So the servo will settle when the temperature of the block increases by 0.9%/3%/°C =0.3°C. There is a small temperature offset between the temperature sensor and the device whose temperature we wish to control. Since the sensor is located very near the heat source, the sensor will be warmer, and the temperature offset will increase as more heat is required. To compensate for this effect, a small portion of a voltage proportional to the baseplate temperature (10mV/°C) is summed to the voltage at the inverting input of the error amplifier. This is the electronic equivalent of a double oven, as the errors due to changes in ambient temperature are greatly reduced. U200B controls the current in the heaters in proportion to the signal from error amplifier (U200A). When the output of the error amplifier goes up, the output of U200B goes down, increasing the current in the heaters, causing the signal XTAL_SHUNT- to go down. The gain (from error amplifier to shunt voltage) is set by R207 and R208. Offsets are arranged so that the heaters will be off when the output of the error amplifier is less than +5Vdc. Conversion to 10MHz TTL U205 converts a 10MHz offset sinewave from the crystal oscillator into complimentary 10MHz TTL level signals. The +10MHZ signal is used as a reference for the microwave frequency synthesizer and the -10MHZ signal is used as a clock for the microprocessor. Separate signals are used to improve the isolation between the CPU and the synthesizer. The 10MHz sine has an offset of 8.2Vdc and an amplitude of 10Vpp and is sourced via a 2.0kΩ resistor. After attenuation by R249, R250 and C210, the non-inverting input to U205 PRS10 Rubidium Frequency Standard 46 Circuit Descriptions sees a signal with 0.91Vdc offset and an amplitude of 0.91Vpp, while the inverting input is biased at 0.91Vdc. Photocell Amplifier The output from the photocell is a sink current which is proportional to the light intensity of the discharge lamp as attenuated by the resonance cell. The light transmission through the resonance cell decreases slightly (by about 1 part in 1000) when the microwave synthesizer sweeps through the hyperfine transition frequency. The microwave frequency is modulated at 70Hz, so the light output will dip at 140Hz when centered on the hyperfine transition. The S/N of the photocell is limited by shot noise: the shot noise current on a dc current of I amps is given by √(2qI) (amps/√Hz) where q=1.6x10-19. On a 50µA dc current the best we can do is 4pA/√Hz of noise. A good design requires that the shot noise be the dominate noise term. U206A is a low noise bipolar input op-amp whose input range includes ground. A 150kΩ metal film resistor shunted by a 1nF film capacitor is used in feedback, providing a transconductance bandwidth of 1kHz. The input current noise of the op-amp (0.4pA/√Hz) and the Johnson noise current of the feedback resistor (0.33pA/√Hz) are not important noise terms. Also, the voltage noise of the op amp (3nv/√Hz) times the noise gain (which is about 10x for a photocell whose shunt resistance is 1MΩ at 25°C, but drops to 15kΩ at the operating temperature of 80°C) is not important as the expected shot noise current times the transconductance gain is about 600nV/√Hz. The transconductance amplifier is followed by a high gain amplifier (x288 for ac signals). This amplifier has a pass band from 16Hz to 1.6kHz. The non-inverting input to this amplifier is biased to place the output of the following bandpass filter at midscale. A two-pole Butterworth low pass filter (300Hz bandwidth) is used to reduce noise at the A/D input, while preserving gain between 70Hz and 140Hz. The filter has a gain of 1.59 for signals in the pass band. The input voltage noise specifications for the high gain and filter amplifiers are not particularly important as there is about 600nV/√Hz of noise on the output of the transconductance amplifier. With an noise equivalent bandwidth of about 400Hz, we expect a total noise (from the shot noise of the photocell’s dc current) of about 3.4mVrms or about 17mVpp. This is much larger than the LSB (1.25mV) of the A/D converter, so the quantization noise of the A/D will not be important. PRS10 Rubidium Frequency Standard Circuit Descriptions 47 Signal Filters for Oscillator Control The amplitude and frequency of the crystal oscillator are controlled by signals from D/A converters. In order to preserve low phase noise, these signals must have very little voltage noise. The EFC signal has a full scale of 17Vdc, and a resolution of 22 bits. A LSB represents a step of about 4µV which is a fractional frequency step of about 1:10-12. We would like for noise on the EFC to be less than one LSB. To arrange this, the DAC22 signal is filtered with a time constant of 1s and buffered by a FET input op-amp (U210B, an AD822). The FET opamp has 1/f noise of about 2µVpp in the two decade band from 0.1Hz to 10Hz. Both the opamp and the 10.0kΩ feed back resistor will have noise of about 30nV/√Hz at 10Hz, which is well under the target of 1.6µV/√Hz required to meet the specification of -125dBc/Hz at 10Hz offset. The oscillator’s amplitude control is filtered is a similar fashion, using U210A. Noise on this signal would be detrimental to the phase noise spectrum, but would not affect zero-crossings of the sine output. Analog Multiplexers There are 16 analog signals which may be multiplexed to the 12-bit A/D converter. One of these signals, PHOTO_AMP, is be digitized 32 times during each cycle of the 70Hz modulation (2240 Hz) in order to lock the crystal to the Rb hyperfine transition. The other 15 signals are monitored intermittently and in response to RS-232 requests. A0 A1 A2 A3 A4 A5 A6 A7 B0 B1 B2 B3 B4 B5 B6 B7 Amplified and filtered photocell signal Photocurrent (x150kΩ/4) (37.5mV/µA) Case temperature (10mV/°C) Crystal thermistor voltage Resonance cell thermistor voltage Lamp thermistor voltage Calibration voltage (Pot or user input) Signal Ground J204 (Spare) +24_HEAT/10 +24_CLEAN/10 Discharge lamp FET’s drain voltage Discharge lamp FET’s gate voltage Crystal heater control signal Resonance cell heater control signal Discharge lamp heater control signal PRS10 Rubidium Frequency Standard 48 Circuit Descriptions Schematic RB_F3 (Sheet 3 of 6) All of the components shown on this schematic reside on the vertical PCB on the left side of the unit. The large hole in this PCB allows access to an SMB connector to sample the microwave field in the resonance cell. Power on reset, low voltage protection, and a watch-dog time-out is provided by U300, a MAX705. The RESET input to the microcontroller is asserted on power-up. The reset will be asserted for about 1 second after power is applied (to allow time for the 10MHz crystal oscillator to start.). A non-maskable interrupt (XIRQ) is asserted if the SPI clock is inactive for more than 1.6 seconds, which should never occur. A maskable interrupt (IRQ) is asserted (which will also retrigger the reset cycle) when the +18V supply drops below 16.0Vdc. Microcontroller The system is controlled by U302, a MC68HC11E9, which is an 8-bit microcontroller with RAM, ROM, EEPROM, A/Ds, UART, serial interface, timers, and I/O control bits. The controller is clocked by the 10 MHz timebase which is to be disciplined to the atomic transition frequency. The microcontroller communicates with external devices via a the serial peripheral interface (SPI). Data is clocked by SPI_CLK to (or from) these devices on SPI_DATA. To reduced digital crosstalk to the most sensitive devices, the SPI data and clock are gated, so that these outputs are only active when necessary. The microcontroller is also responsible for a variety of housekeeping tasks: power on circuit checks, setting and reading temperatures, boost-starting the discharge lamp, digitally filtering the frequency-lock error signal, passing the filtered error signal to the 22 bit D/A converter, and responding to commands and queries via the RS-232 interface. A description of I/O from the controller follows: Name Function CLK RESET XIRQ IRQ MODA MODB 10MHz TTL clock input TTL low to assert system reset Non-maskable interrupt on watch-dog time-out (SPI dead) Maskable interrupt on power failure (+18 goes below +16V) Configure for internal program memory Configure for internal program memory PORT A Mixed inputs and outputs PA0 PA1 Time tag input to measure 1PPS input to 400ns Interpolation input to measure 1PPS input to 0.2ns PRS10 Rubidium Frequency Standard Circuit Descriptions PA2 PA3 PA4 PA5 PA6 PA7 ADC_BUSY input is high during 12-bit A/D conversions MAG_SIGN output controls sign of magnetic field -CONV strobe low to initiate 12-bit A/D conversion EN/-CLR control for 1PPS time-tagging 1PPS output strobe (400ns resolution) Spare output (connected to J305) PORT B Eight TTL outputs PB0 PB1 PB2 PB3 PB4 PB5 PB6 PB7 MPX0 Select bit for analog multiplexer MPX1 Select bit for analog multiplexer MPX2 Select bit for analog multiplexer MPX3 Low to select MPX-A, high for MPX-B 1PPS_SEL0 Low bit for 100ns 1PPS output delay 1PPS_SEL1 High bit for 100ns 1PPS output delay Spare (connected to J306) LOCKED bit is set high to indicate Rb frequency lock PORT C Chip select outputs PC0 PC1 PC2 PC3 PC4 PC5 PC6 PC7 -CS_PLL -STB_DAC8 -CS_EFC_HIGH -CS_MAGNET Spare (connected to J308) -CS_EFC_LOW -CS_PHASE_MOD EN_ADC_CLK PORT D SPI and RS-232 PD0 PD1 PD2 PD3 PD4 PD5 RS-232_IN RS-232_OUT SPI_IN SPI_DATA SPI_CLK SPI_GATE PORT E Octal 8-bit A/D converter with +5.12V full-scale PE0 PE1 PE2 RF_XVCO. Should be between 0.2 and 3.5Vdc RF_VCO. Should be between 3.0 and 4.0Vdc RF_AGC. Should be 1.0 and 3.75Vdc 49 PRS10 Rubidium Frequency Standard 50 Circuit Descriptions PE3 PE4 PE5 PE6 PE7 PLL_LOCK. Should be >4.0Vdc Ground Spare analog input (J302 with 100kΩ to ground) Spare analog input (J303 with 100kΩ to ground) Spare analog input (J304 with 100kΩ to ground) RS-232 The system may be controlled by commands sent via the RS-232. Two pins on the system connector (J100) are used for transmit and receive. Data is sent to the host on pin 4, received from the host on pin 7. The baud rate is fixed at 9600 baud, 8 bits, no parity, with 1 start and 2 stop bits. No DTR or CTS controls have been used, rather, the XON/XOFF protocol has been implemented. The transmit drive level is 0 and 5V, not the +/-12V normally associated with RS-232. These levels are compatible with RS-232 line receivers, but does not require their use (a TTL inverter may be used instead), hence simplifies the interface when used inside an instrument at the sacrifice of degraded noise immunity over long lines. 12 Bit A/D Conversion A serially interfaced 12 bit A/D converter is used to measure the ac and dc components of the photocell signal. The analog input to the ADC is buffered by U309A, a FET input op-amp configured as a unit follower. The quantization noise of this converter will not degrade the S/N of the ac signal, even in the case when the ac signal occupies a relatively small portion of the converter's full scale range. The A/D converter can also measure the position of a 10 turn "user cal" pot, which has a (software defined) range of +-2E-9. The 12 bits of resolution will provide a frequency trim of 1E-12. 12-Bit Digital to Analog Converters There are four 12-bit DACs. Two of the DACs are scaled, summed, and offset to provide a level with 22-bits of resolution to control the crystal frequency. One of the DACs is used to control the magnitude of the magnetic field in the resonance cell. The forth DAC is used to digitally synthesize the 70Hz phase modulation of the 6.834GHz microwave field. Two of the DACs ( the upper DAC of the 22-bit pair and the DAC which controls the magnetic field ) are rarely changed and would be very sensitive to digital crosstalk and so are communicated with via the gated SPI interface. Magnetic Field Control R331, a 348Ω shunt resistor, is used to measure the current through the magnetic field coil which is in the resonance cell. U307B, an LM358 op amp, maintains a current through the field coil so that the voltage across the shunt resistor matches the output from the 12-bit DAC (U310, an LTC1452). The coil current can be programmed from 0 to 8mA, but a minimum level (3mA) is always maintained to spread out the non 0-0 Zeeman transitions. The PRS10 Rubidium Frequency Standard Circuit Descriptions 51 frequency offset is quadratic in the field strength, with a fractional frequency resolution of about 1x10-12 at 3mA, and of 2.5x10-12 at 8mA. To reduce the susceptibility of the transition frequency to external magnetic fields, the polarity of the magnetic field is chopped at 5Hz by the CPU control signal (MAG_SIGN) and U306 (a DG211 quad analog switch). The apparent transition frequency is synchronously filtered by the CPU over the field reversal period so as to notch out any 5Hz noise from the EFC signal. Phase Modulation The main task for the microcontroller is to modulate the microwave carrier to sweep through the Rb hyperfine transition frequency. The microcontroller will A/D the optical signal via a 12 bit A/D converter, synchronously detect the components of the optical signal at the sweep rate and at twice the sweep rate, and adjust the frequency of the 10 MHz timebase so as to null the component at the sweep rate (which keeps the optical dip centered in the middle of the sweep). The CPU digitally synthesizes the 70Hz sinewave which phase modulates the RF frequency synthesizer. U313, an 12-bit DAC, outputs 32 samples during each cycle of the 70Hz sinewave. The amplitude of the sinewave is controlled by the signal “PHASE_DEV”, which comes from an 8-bit DAC on the frequency synthesizer PCB. The amplitude of the sinewave controls the magnitude of the frequency deviation (which is adjusted to optimize the deviation sensitivity of the resonance cell). The frequency deviation is about ±300Hz at 6.834GHz. 1PPS Output A port bit on the microcontroller (PA7) may be used to output a 10µs pulse at a rate of 1Hz. This pulse is combined with the LOCK output signal on the main connector (pin 1 of J100). (The function of the LOCK/1PPS output may be configured via RS-232.) This port bit is controlled by the microcontroller’s timer which has a resolution of one E_CLK cycle (400ns). Hardware on the bottom circuit board provides delays in 100ns steps (under control of the port bits 1PPS_SEL0 and 1PPS_SEL1) and in steps of about 0.5ns via an analog signal from an 8-bit DAC. The combination of these three delays allows the 1PPS output pulse to be placed with an accuracy, resolution, and differential non-linearity of about 1ns. 1PPS Input Time-Tag The rising edge of a 1PPS input signal on pin 5 of the main connector can be time-tagged with 1ns resolution. The time may reported via RS-232, or used to servo the unit to another frequency standard (such as GPS). PRS10 Rubidium Frequency Standard 52 Circuit Descriptions Hardware on the bottom board provides two signals: TIME_LATCH and INTERPOLATE. These signals latch the value of a free-running counter (clocked by the E_CLK) which is part of the microcontroller. TIME_LATCH is just the 1PPS input re-synchronized to the CPU’s E_CLK, which allows the processor to time-tag the input to 400ns resolution. INTERPOLATE will go low for a time equal to about 2000 times the interval between the 1PPS input and the next E_CLK. Measuring the duration of INTERPOLATE allows the position of the 1PPS input to be measured to about 400ns/2000=0.2ns. Schematic RB_F4. (Sheet 4 of 6) High Resolution, Low Phase Noise, RF Synthesizer The pressure tuned Rb hyperfine transition lies at about 6,834,685,850Hz. This will vary depending on the fill pressure and gas composition of the Rb resonance cell. In order to lock the crystal oscillator to this transition, we need to synthesize and sweep frequencies in this region. In order to minimize the amount of magnetic field tuning needed, the frequency synthesizer should be capable of being set with high resolution (about 1:10-9). In order to detect the transition with good signal to noise, the synthesizer will need to have very low phase noise (on the order of -70dBc/Hz at 6.8GHz). Since we want to stabilize a 10.000MHz crystal to an (essentially) arbitrary frequency with low phase noise, we will need a dual loop synthesizer: a fast loop to stabilize an RF VCO to a crystal (for good phase noise), and a slow loop to stabilize the crystal to the 10.000MHz reference. Typical numbers: A typical microwave frequency is 6,834,685,853Hz Which is the 19th harmonic of the RF frequency: 359,720,308Hz Which is 16 times the crystal frequency: 22,482,519Hz In this case, dividing the RF frequency by (1386*64+39)=4053.5Hz Which equals the reference frequency (10,000,000Hz) divided by 2467. The dual modulus frequency synthesizer will be programmed with R=2467, N=1386, and A=39. The microwave frequency is generated by frequency multiplication of the RF frequency in a step recovery diode (SRD). The RF frequency was chosen to give good conversion efficiency, with favorable “numerology” (so that the gaps between available frequency steps from the dual modulus synthesizer are small). A reasonable crystal frequency is the RF frequency divided by 16 (dividers and oscillator/mixers are available in this frequency range). A third overtone crystal resonator with a nominal frequency of 22.48252MHz is used to provide a low-noise “flywheel”. We PRS10 Rubidium Frequency Standard Circuit Descriptions 53 only need to tune over a range of 0.1ppm to accommodate for fill pressure variations of the resonance cell. The varactor tuned crystal oscillator has a tuning coefficient of about 2 ppm/V. The RF VCO is phase locked to this oscillator by a mixer/loop filter combination with a high natural frequency (about 400,000r/s), a high comparison frequency (22.48MHz), and a damping factor of one. Low noise components (metal film resistors, film capacitors and an OP27 op amp) help achieve the low phase noise. The varactor for the crystal is tuned by the dual modulus frequency synthesizer (U400, an MC145190) which compares the divided reference (10.00MHz) to the divided RF (at about 359.72MHz). Since large divisors must be used to achieve the high frequency resolution, the comparison frequency will be low (a few kHz), but the crystal oscillator provides good frequency stability in spite of the low comparison rate. The gain of U400’s phase detector may be set (coarsely) by the CPU, and it is adjusted to maintain roughly the same PLL damping factor as divisors are changed. This loop has a very low natural frequency (about 10 r/s) and a damping factor which ranges from 0.84 to 1.19. After multiplication to 6.834GHz, the phase noise has been measured at -72dBc/Hz. This is low enough so that the S/N of the dip signal is not adversely affected by the microwave phase noise. RF Output Amplifier The 359.720MHz RF must be amplified to drive the SRD. It is important to maintain a constant RF level, optimized to provide a large frequency deviation sensitivity and immunity to RF level variations. The variable gain output amplifier is designed to provide a conjugate match of Q400 (an MFR5812 medium power RF transistor) to the 50Ω source (U404, the VCO) and to the 50Ω load (the SRD, which has its own matching network). The gain of Q400 is adjusted by changing its dc collector current. U406A compares the DAC signal (RF_LEVEL) to the rectified RF current in the SRD (which is the dc current sourced by R444). If the detected RF is low, the output of U406A will ramp up, increasing the output of U406B, which increases the base current to Q400, increasing the available power from Q400. The output of U406A linearly controls the collector current of Q400 from 0 to about 35mA. U406A’s output settles when the detected RF signal on R444 is exactly 1/10th of the RF_LEVEL DAC signal. Step Recovery Diode Matching The output of the RF amplifier is connected to the SRD via an SMB connector. The SRD can be modeled at RF frequencies and at our drive level as a resistor (20-40Ω, depending on PRS10 Rubidium Frequency Standard 54 Circuit Descriptions drive level) with a shunt capacitor (about 1pF) and a series inductor (a few nH). Matching (for best return loss) is achieved by adding a shunt capacitor (5pF) across the SMB and with a series inductor (10nH) to the SRD. The SRD is inside the mu-metal can which encloses the resonance cell and photodetector. The can is not resonant at the microwave frequency (as is common practice), and so there is no need to tune the length of the cavity or worry about the affect of coming off resonance. Sufficient field strength at 6.834GHz is available without resonant enhancement due to the high RF drive frequency and efficient coupling into the SRD. The SRD loop is oriented inside the can in such a way as to minimize the drive level required for a good hyperfine optical signal. Analog Control Various analog voltages are provided by an octal 8-bit DAC to control temperatures, intensities, and for system tests. U407, a TLC5628, is connected to the microcontroller via the gated serial interface. Each of the eight analog outputs may be set from 0 to 4.00V with 10mV resolution. (Except for the PHASE_DEV output, which has a full scale of 2.00V and a step size of 5mV.) The outputs are dedicated as follows: OUTPUT A B C D E F G H NAME DESCRIPTION RF_LEVEL 1PPS_DELAY LAMP_DRAIN LAMP_TSET XTAL_TSET CELL_TSET OSC_AMPL PHASE_DEV Controls the RF power level to the SRD Analog control of 1PPS output delay (0.5ns/bit) Drain voltage (x6) to lamp FET Controls the lamp temperature (Tmax=122°C) Controls the crystal temperature (Tmax=90°C) Controls the cell temperature (Tmax=90°C) Controls the 10.00MHz output amplitude Controls the frequency deviation of RF Schematic RB_F5 (Sheet 5 of 6) Power Supply, Lamp Control and 1PPS Timing PCB Components shown on this schematic are located on the bottom PCB. Three TO-220 power regulators are mounted to the back wall of the device. Linear Power Supplies All of the power supplies operate from the +24_CLEAN input (pin 9 of the main connector). U503, an LM317 adjustable voltage regulator, is used to supply +18Vdc to the system. The +18V is used on the analog PBC, on the frequency synthesizer, for the crystal oscillator, and for the analog switches and ADC buffer on the CPU PCB. PRS10 Rubidium Frequency Standard Circuit Descriptions 55 U504, an LM340-5 three terminal regulator is used to provide +5.0Vdc. This supply is used for all logic circuits and for analog circuits which interface to analog devices which must not be driven above their logic supplies. Lamp Regulator A discharge is ignited and maintained by a MOSFET powered oscillator operating at about 150MHz inside the lamp enclosure. It is very important that the voltage provided to the lamp circuit be well regulated, as the lamp intensity is nearly proportional to this voltage. Since the synchronously detected light signal at 70Hz is used to lock to the hyperfine transition, noise at 70Hz will add noise to the frequency lock-loop. Also, noise at other frequencies may be heterodyned by the 2ω signal (140Hz), which is really a modulation of the attenuation of light through the resonance cell. For example, if the power supply has noise at 210Hz, the lamp will have an intensity fluctuation at 210Hz, which when mixed by the 140Hz attenuation modulation will create a component at 70Hz, which will interfere with the frequency lock loop. Long term stability (thermal and aging) of the lamp voltage regulator is also important. The voltage provided to the lamp oscillator affects the operating conditions of the lamp (temperature, Rb vapor pressure, and discharge intensity) which will affect the apparent hyperfine transition frequency. The drain voltage and current are controlled by the lamp regulator. The gate voltage to the MOSFET is controlled so that the drain current is about 60mA + (10mA/V)*Vdrain. The gate voltage is supplied by U502B which measures the drain current through the shunt resistors R504, R505, R552 and R553. The offset and slope of the drain current vs. drain voltage is set by R510 and R511. The drain voltage is controlled by an 8bit DAC whose output is multiplied by 6 and buffered by U502 and Q500. An adjustable regulator, U501, is bootstrapped at 1.75Vdc above the drain voltage. This regulator will provide the drain current for drain voltages above 6.25Vdc. When the drain voltage is set below 6.25Vdc, the drain current is sourced from a +8V regulator, which is part of the lamp heater circuit. (This is done to reduce the power required by the unit by redirecting the heat of the regulator to the lamp block which needs to operate at a high temperature.) To start the discharge, the drain voltage to the MOSFET is set to about 20Vdc, which is regulated from the +24_HEAT supply. The drain voltage is reduced to about 5V after the lamp starts. 1PPS Input Time-Tag The rising edge of a 1PPS input signal on pin 5 of the main connector can be time-tagged with 1ns resolution. The time may reported via RS-232, or used to servo the unit to another frequency standard (such as GPS). PRS10 Rubidium Frequency Standard 56 Circuit Descriptions Hardware on this board provides two signals: TIME_LATCH and INTERPOLATE. These signals latch the value of a free-running counter (clocked by the E_CLK) which is part of the microcontroller. TIME_LATCH is just the 1PPS input re-synchronized to the CPU’s E_CLK, which allows the processor to time-tag the input to 400ns resolution. INTERPOLATE will go low for a time equal to about 2000 times the interval between the 1PPS input and the next E_CLK. Measuring the duration of INTERPOLATE allows the position of the 1PPS input to be measured to about 400ns/2000=0.2ns. The E_CLK is synchronized to the 10MHz clock, and four phases are generated by U500, an octal latch. E_0 is used to synchronize EN/-CLR (U506A), and E_90 is used to arm the timetagging circuit (U507A). A gate pulse (the output of U507B) will start with the first 1PPS input after U507A is set, and end synchronously with the first E_180 rising edge after the first E_90 rising edge after the 1PPS input. This will generate a gate pulse of 100ns to 500ns duration that is a measure of the position of the 1PPS input relative to the E_CLK. The width of the gate pulse is multiplied by a factor of about 2000 by the pulse stretcher circuit. Initially, C509 is charged to 11.4Vdc. C509 is rapidly discharged by Q502’s collector current (about 10.8mA) during the gate pulse, driving the output of the comparator (U509) low. C509 is then recharged by Q501, a 5.4µA constant current source. When C509 reaches 11.0V, the output of the comparator goes high. The ratio of the collector currents of Q501 and Q502 sets the stretch multiplier. The circuit is temperature compensated against variations in the transistors’ base-emitter voltages as both the charge and discharge currents are equally affected by their junction temperature, leaving the ratio unchanged. 1PPS Output Pulse Delay A port bit on the microcontroller (PA7) may be used to output a 10µs pulse at a rate of 1Hz. This port bit is controlled by the microcontroller’s timer which has a resolution of one E_CLK cycle (400ns). Hardware on this circuit board provides delays in 100ns steps (under control of the port bits 1PPS_SEL0 and 1PPS_SEL1) and in steps of about 0.5ns via an analog signal from an 8-bit DAC. The combination of these three delays allows the 1PPS output pulse to be placed with an accuracy, resolution, and differential non-linearity of about 1ns. The 1PPS port bit from the CPU is synchronized to E_0 by U506B, then synchronized and delayed by U500. The multiplexer, U510, selects one of the four phases of the 1PPS output, delayed in steps of 100ns by the 10MHz clock. The selected 1PPS pulse may be delayed by an analog control signal. C513 is charged to a level of 10+Vdac/2 by Q503’s collector current, which turns on D503, connecting C513 to the output of U512B. The selected 1PPS output turns Q503’s current down, and turns Q504’s current up, discharging C513. As C513 passes through 9.0Vdc, the comparator output (U514) is forced low. C513 continues to discharge down to 8- Vdac/2, where it stays until the 1PPS PRS10 Rubidium Frequency Standard Circuit Descriptions 57 pulse goes low. When the 1PPS pulse goes low, the process is reversed, and Q504’s current is reduced while Q503’s current is increased, charging C513 back towards 10+Vdac/2. This time, as C513 passes through 9.0V, the comparator’s output is set high. In this way, both the leading and trailing edges off the 1PPS output are delayed the same amount. Baseplate Temperature Sensor U505, an LM45 centigrade temperature sensor, has an output of 10mV/°C. This sensor is in thermal contact with one of the baseplate standoffs that hold the thermal shield which encloses the lamp. The sensor’s output may be read by the CPU via the 12-bit DAC so that the baseplate temperature may be read with 0.125°C resolution. The output of the temperature sensor is also used to tweak the setpoints of the temperature control servos, which will reduce the affect of ambient temperature changes on the temperatures of the lamp, resonance cell, and crystal ovens. Schematic RB_F6 (Sheet 6 of 6) Resonance Cell and Lamp Heaters The heater and control circuits for the lamp and resonance cell are identical to the circuit described for the crystal oscillator. (See Sheet 1 of 1.) The resonance cell heaters (U600 and Q600) are located on the back of the resonance cell. The lamp heaters (U800 and Q800) are located on the bottom of the lamp block. The other passive components are located on the small vertical PBCs attached to the back of the resonance cell and lamp blocks. The control circuits of the heaters are located on the top PCB. Resonance Cell Components shown inside the resonance cell include: L700, a 50 turn magnetic field coil, D700, the SRD with its input matching network mounted on an SMB connector, and D701, the photodiode. Another SMB connector, J701, is used to pick-up some of the microwave field to allow diagnostic tests with an RF spectrum analyzer. Discharge Lamp A plasma discharge is maintained inside a small bulb (filled with a few Torr of an inert gas and some Rb metal) by an RF oscillator. The oscillator operates at about 150MHz, with a peak-to-peak voltage of about 10 times the dc voltage applied to the FET’s drain. Q900, an MRF134 medium power n-channel FET, is used as the active element in the oscillator circuit. This part is characterized for operation at +28Vdc and 150MHz, and is rated for a dissipation of 9.5W (derated for our 105°C operation). Our most severe operation is during lamp ignition, with an total input power of about 3.2W. The total input power PRS10 Rubidium Frequency Standard 58 Circuit Descriptions during normal operation is 0.5W. (The power dissipated in the MRF134 is probably about 1/2 the total input power.) The oscillator current circulates through the series LC network consisting of C903-906 and L903. The coil, L903, is in contact with the bulb. The high voltage end of the coil connects to C905. When oscillating, the drain of the FET swings between ground and twice the dc drain voltage. C903 is in parallel with the FET’s drain-source capacitance (about 10pF), for a total capacitance of 78pF (or a reactance of about –j13.6Ω at 150MHz). With a drain voltage of 20Vdc, the drain will have about 40V peak-to-peak, so there will be a circulating current of 2.9A, peak-to-peak. The series capacitance of C904/C905 is 9pF (a reactance of about j118Ω), so they will have about 340Vpp across the pair (due to the circulating current), which is in phase with the 40Vpp drain voltage, for a total of 380Vpp at the top of the coil. It is very important that C903-906 be very low loss and high stability capacitors. Porcelain capacitors are used in this circuit: they have Qs of about 500, for ESRs of about 0.03Ω (for the 56pF part at 150MHz). Low loss is important to reduce self-heating (which can destroy other types of capacitors), and high stability is important to maintain a constant discharge intensity. The operation of the oscillator depends somewhat on the conditions of the discharge. Over certain temperature ranges (which are carefully avoided) the losses caused by the discharge can quench the oscillation, which stops the discharge, which allows the oscillation to start again. This cycle can occur at several kHz, which makes frequency locking impossible. PRS10 Rubidium Frequency Standard Circuit Descriptions 59 Schematic RB_F7 (Sheet 1 of 1) Connector Interface Board (Not part of standard product) This board is not part of the standard product and is available from the factory at and additional charge. It is intended to facilitate customer evaluation of the product by adapting the standard product’s interface connector to connector types which are more readily available in the laboratory (such as BNCs and DB9 for RS-232). This board connects to the outside of the unit. Three BNCs are used to source 10MHz and the 1PPS outputs, and to receive the 1PPS input. A DB9(female) allows direct connection to a computer (usually via COM2:). A 2.1mm power connector allows the unit to be connected to a standard +24V/2.5A power supply (center conductor must be positive). The 10MHz output should be terminated into a 50Ω load. The output will be about 0.5Vrms (about 1.41Vpp). The RS-232 interface uses CMOS logic levels (0V and +5V) which will work with standard RS-232 line drivers and receivers. The ±12V of the standard RS-232 line driver will not harm the logic input, and the 0/+5V RS-232 output from the rubidium standard will work with virtually all computers, provided the cable is less than 25 feet long. The RS-232 control lines, CD, DSR and CTS are all pulled high via 10kΩ resistors. An XON/XOFF protocol is used to pause communications as needed. The LOCK/1PPS function may be configured via RS-232. The factory default is a low level to indicate lock, with a 10µs pulse to +5V at 1PPS, with the leading edge being defined as the 1PPS timing reference. This BNC output is a CMOS logic output via a 1kΩ resistor. LEDs are used to indicate +24 power (electronics and heaters), lock status, and RS-232 data received and RS-232 data transmitted. PRS10 Rubidium Frequency Standard 60 Appendix A Appendix A: Frequency Synthesizer Table This table provides a list of frequency synthesizer parameters and the frequency offset relative to the settings for a nominal cell. Also listed is the frequency step between adjacent settings. This information is needed to calibrate units which have aged by more than ± 2x10-9, or in the case that an application may require operating the unit at a frequency up to 0.6Hz away from 10MHz. Number R N A f-fo(Hz) df(hz) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 6900 6757 6614 6471 6328 6185 6042 5899 5756 5613 5470 5327 5184 5041 4898 4755 4612 4469 4326 4183 4040 3897 3754 3611 7079 3468 6793 3325 6507 3182 6221 3039 5935 2896 5649 2753 3878 3797 3717 3637 3556 3476 3395 3315 3235 3154 3074 2994 2913 2833 2752 2672 2592 2511 2431 2351 2270 2190 2109 2029 3978 1949 3818 1868 3657 1788 3496 1708 3335 1627 3175 1547 15 55 31 7 47 23 63 39 15 55 31 7 47 23 63 39 15 55 31 7 47 23 63 39 54 15 6 55 22 31 38 7 54 47 6 23 0.000000 -0.005963 -0.012183 -0.018678 -0.025467 -0.032570 -0.040009 -0.047809 -0.055996 -0.064600 -0.073654 -0.083195 -0.093261 -0.103899 -0.115158 -0.127094 -0.139771 -0.153258 -0.167638 -0.183000 -0.199450 -0.217108 -0.236110 -0.256618 -0.267493 -0.278816 -0.290617 -0.302924 -0.315773 -0.329199 -0.343243 -0.357947 -0.373360 -0.389534 -0.406527 -0.424402 0.005963 0.006220 0.006495 0.006789 0.007103 0.007439 0.007800 0.008187 0.008604 0.009054 0.009540 0.010067 0.010638 0.011259 0.011936 0.012676 0.013488 0.014379 0.015362 0.016450 0.017657 0.019002 0.020508 0.010875 0.011324 0.011800 0.012308 0.012849 0.013426 0.014043 0.014704 0.015413 0.016174 0.016993 0.017875 PRS10 Rubidium Frequency Standard Number 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 R 5363 2610 5077 2467 7258 4791 7115 2324 6829 4505 6686 2181 6400 4219 6257 2038 5971 3933 5828 1895 5542 3647 5399 7151 1752 6865 5113 3361 4970 6579 1609 6293 4684 3075 4541 6007 1466 N 3014 1466 2853 1386 4079 2692 3999 1306 3838 2532 3757 1225 3597 2371 3516 1145 3356 2210 3275 1065 3114 2049 3034 4019 984 3858 2873 1889 2793 3697 904 3537 2632 1728 2552 3376 823 A 22 63 38 39 29 54 5 15 21 6 61 55 13 22 53 31 5 38 45 7 61 54 37 20 47 36 53 6 29 52 23 4 45 22 21 20 63 f-fo(Hz) -0.443231 -0.463091 -0.484071 -0.506266 -0.521791 -0.529786 -0.537941 -0.554753 -0.572269 -0.581306 -0.590535 -0.609599 -0.629515 -0.639810 -0.650341 -0.672141 -0.694986 -0.706824 -0.718952 -0.744123 -0.770593 -0.784348 -0.798466 -0.805666 -0.827855 -0.850968 -0.858888 -0.875065 -0.891707 -0.900209 -0.926471 -0.953926 -0.963357 -0.982657 -1.002566 -1.012757 -1.044325 df(hz) 0.018829 0.019860 0.020979 0.022195 0.015526 0.007995 0.008155 0.016812 0.017516 0.009036 0.009229 0.019064 0.019916 0.010295 0.010531 0.021800 0.022845 0.011838 0.012128 0.025171 0.026470 0.013754 0.014118 0.007200 0.022189 0.023113 0.007920 0.016177 0.016642 0.008502 0.026261 0.027455 0.009431 0.019301 0.019908 0.010191 0.031568 Appendix A Number 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 R 7187 5721 4255 7044 2789 6901 4112 5435 6758 1323 6472 5149 3826 6329 2503 6186 3683 4863 6043 7223 1180 6937 5757 4577 3397 5614 2217 N 4039 3215 2391 3959 1567 3878 2311 3054 3798 743 3637 2894 2150 3557 1406 3476 2070 2733 3396 4059 663 3899 3235 2572 1909 3155 1246 A 35 36 37 11 38 51 13 52 27 39 43 4 29 19 54 59 5 20 35 50 15 2 51 36 21 27 6 f-fo(Hz) -1.070709 -1.077471 -1.088890 -1.098166 -1.112316 -1.126759 -1.136556 -1.148995 -1.156563 -1.187656 -1.220123 -1.228465 -1.242576 -1.254056 -1.271605 -1.289559 -1.301761 -1.317282 -1.326742 -1.333111 -1.365727 -1.399688 -1.406649 -1.417199 -1.435079 -1.449656 -1.471991 61 df(hz) 0.026385 0.006761 0.011420 0.009275 0.014150 0.014444 0.009796 0.012439 0.007569 0.031093 0.032467 0.008342 0.014111 0.011480 0.017548 0.017954 0.012202 0.015521 0.009460 0.006369 0.032616 0.033961 0.006961 0.010550 0.017880 0.014577 0.022336 PRS10 Rubidium Frequency Standard 62 Appendix B Appendix B: Precision Frequency Measurement One goal for the calibration of the PRS10 is to set the frequency to within 1 part in 1011 of 10MHz (which is 10MHz ± 0.0001Hz, or 10MHz ±100µHz). Two things are required to make this measurement: (1) a very good 10MHz frequency reference, and, (2) a very good time-interval counter. The frequency reference should be stable and accurate to a few parts in 1012. Another PRS10 locked to the 1pps from a GPS receiver, or a cesium beam standard (such as HP 5071A), are two possibilities. The time-interval counter needs to measure time intervals with a resolution of better than 50ps, and should be able to do fast averaging of the time-interval measurements. Suitable instruments include the SR620 or an HP5370B. The time-interval counter may be used to directly measure the frequency of the device under test (DUT). In this case, the frequency reference is used as the timebase for the time-interval counter. Unfortunately, the time-interval counter will require about 100 seconds to measure the frequency to a resolution of 1 part in 1012 when used in the frequency measurement mode. A faster way to make the comparison between the reference frequency and the DUT is to use the time interval measurement mode of the counters. In this case, the time intervals between the 10MHz zero crossings of the reference frequency and the DUT are measured and averaged. If this time interval changes by less than 10ps per second, then the DUT is within 1 part in 1011 of the frequency reference. This technique is very similar to the technique of offsetting the reference frequency from the DUT, mixing the two sources, amplifying and filtering and measuring the frequency of the beatnote. (Often referred to as a heterodyne measurement.) However, the time interval measurement technique does not require mixers or amplifiers or offsetting the reference from the DUT. The resolution of the time-interval technique is remarkable. Each time-interval measurement has an rms jitter of about 25ps (in the case of the SR620). As the jitter is randomly distributed, the jitter of the mean is reduced by the square root of the number of samples. For a 1000 sample measurement, (which takes less than one second to complete) the rms jitter of the mean will be less than 1ps, and the difference between two time interval measurements will have a jitter of less than 2ps. This provides a relative frequency measurement to 2 parts in 1012 in 2 seconds. PRS10 Rubidium Frequency Standard Appendix B 63 Set-up for an SR620 Described here is the set-up for an SR620 Time Interval Counter to make precision frequency measurements. For a detailed description for the operation of the SR620, refer to the instrument’s operation and service manual. Four input connections: The 10MHz reference frequency is connected to both the rear panel 10MHz input and to the “A” (START) input. (Place the tee on the rear panel input.) Connect the 10MHz from the DUT to the “B” (STOP) input. Connect the 1kHz TTL square wave from “REF” output to gate “EXT” input BNC. Four input setups: From the front panel “CONFIG” menu, use “SET” to choose the “cAL” menu, then use “SELECT” to select the “cLoc SourcE”. Use the arrow keys to set the clock source to “rEAr”. This will allow the SR620 to use the 10MHz reference frequency which has been applied to the rear panel 10MHz input as the timebase for all measurements. Set the “EXT” gate input “LOGIC” to POS, “TERM” to 50Ω, and “LEVEL” to +1.0V. The “TRIG” LED will go on when the “GATE/ARM” is setup properly. Both “A” (START) and “B” (STOP) are AC coupled and terminated into 50Ω. The “SLOPE” is set to “+”, and the “LEVEL” is turned full counter-clockwise to “AUTO” and the “UHF” LED should be off. The “TRIG” LEDs will be on when the 10MHz sources are present. “Coarse” Frequency Measurements You should verify that the DUT is very close (within 0.1Hz) to 10MHz. To measure the frequency, set “MODE” to “FREQ”, set “SOURCE” to “B”, set the “GATE/ARM” to 1s, and set the “SAMPLE SIZE” to 1. Hold the “START” button down for a few seconds to start continuous measurements. Set the display to “MEAN” to display the frequency of the 10MHz output from the DUT. “Fine” Frequency Measurements If the 10MHz from the DUT is within 0.1Hz of 10MHz, you may use the “fine” frequency measurement technique to make measurements to a few parts in 1012 in a one second interval. As explained above, the frequency offset between the reference and the DUT is inferred by time-interval measurements between their zero-crossings. To carry out these measurements: Set the “MODE” to “TIME”, select the “SOURCE” (of START) to “A”, set the “GATE/ARM” mode to “+TIME” and “EXT”, and set the PRS10 Rubidium Frequency Standard 64 Appendix B “SAMPLE SIZE” to 1000. With the external gate triggered by the SR620’s 1kHz reference output, the unit will display a new “MEAN” every second. If the DUT is adjusted so that the mean of the time interval measurements changes by less than 10ps per second, then the DUT is within 1 part of 1011 of the reference frequency. PRS10 Rubidium Frequency Standard PRS10 Parts List 65 Parts list for Revision H Part reference numbers may be used to help locate the part per the following table: Reference Designator Location 100 to 149 150 to 199 200 to 299 300 to 399 400 to 499 500 to 599 600 to 699 700 to 799 800 to 899 900 to 999 10MHz oven oscillator (front vertical) PCB Crystal heater PCB (front vertical) Analog servos and amplifiers (top) PCB Microcontroller (left-side, vertical) PCB Frequency synthesizer (right side, vert) PCB P/S and 1PPS circuits (bottom) PCB Cell heater PCB (rear vertical) Inside the resonance cell Lamp heater PCB (center vertical) Inside lamp enclosure Rubidium Oscillator PC Board Assembly Parts List REF. SRS PART VALUE DESCRIPTION C 100 C 101 C 102 C 103 C 106 C 107 C 109 C 110 C 111 C 112 C 113 C 114 C 115 C 116 C 151 C 152 C 200 C 201 C 202 C 203 C 204 C 205 C 206 C 207 5-00595-569 5-00299-568 5-00370-552 5-00375-552 5-00298-568 5-00298-568 4-01146-462 5-00299-568 5-00387-552 5-00361-552 5-00375-552 5-00299-568 5-00586-569 5-00586-569 5-00299-568 5-00299-568 5-00387-552 5-00466-572 5-00299-568 5-00387-552 5-00466-572 5-00299-568 5-00387-552 5-00466-572 2.2U/50V .1U 39P 100P .01U .01U 2.00K .1U 1000P 6.8P 100P .1U 4.7UF/50V 4.7UF/50V .1U .1U 1000P .1U .1U 1000P .1U .1U 1000P .1U Cap, Tantalum, SMT (all case sizes) Cap, Ceramic 50V SMT (1206) +/-10% X7R Capacitor, Chip (SMT1206), 50V, 5%, NPO Capacitor, Chip (SMT1206), 50V, 5%, NPO Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R Thin Film, 1%, 50 ppm, MELF Resistor Cap, Ceramic 50V SMT (1206) +/-10% X7R Capacitor, Chip (SMT1206), 50V, 5%, NPO Capacitor, Chip (SMT1206), 50V, 5%, NPO Capacitor, Chip (SMT1206), 50V, 5%, NPO Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Tantalum, SMT (all case sizes) Cap, Tantalum, SMT (all case sizes) Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R Capacitor, Chip (SMT1206), 50V, 5%, NPO SMT Film Capacitors, 50V, 5%, All Sizes Cap, Ceramic 50V SMT (1206) +/-10% X7R Capacitor, Chip (SMT1206), 50V, 5%, NPO SMT Film Capacitors, 50V, 5%, All Sizes Cap, Ceramic 50V SMT (1206) +/-10% X7R Capacitor, Chip (SMT1206), 50V, 5%, NPO SMT Film Capacitors, 50V, 5%, All Sizes PRS10 Rubidium Frequency Standard 66 PRS10 Parts List REF. SRS PART VALUE DESCRIPTION C 208 C 210 C 212 C 216 C 217 C 218 C 219 C 220 C 221 C 222 C 223 C 224 C 226 C 227 C 228 C 229 C 230 C 231 C 232 C 301 C 302 C 304 C 306 C 308 C 309 C 310 C 311 C 400 C 401 C 402 C 403 C 404 C 405 C 406 C 407 C 408 C 409 C 410 C 411 C 413 C 414 C 415 C 416 C 417 C 418 C 419 C 420 C 421 5-00299-568 5-00387-552 5-00299-568 5-00387-552 5-00466-572 5-00299-568 5-00375-552 5-00466-572 5-00454-572 5-00454-572 5-00299-568 5-00299-568 5-00466-572 5-00466-572 5-00299-568 5-00299-568 5-00299-568 5-00375-552 5-00355-552 5-00299-568 5-00299-568 5-00299-568 5-00299-568 5-00298-568 5-00375-552 5-00375-552 5-00586-569 5-00299-568 5-00299-568 5-00387-552 5-00387-552 5-00299-568 5-00299-568 5-00387-552 5-00466-572 5-00298-568 5-00466-572 5-00462-572 5-00299-568 5-00299-568 5-00373-552 5-00375-552 5-00387-552 5-00387-552 5-00375-552 5-00456-572 5-00456-572 5-00299-568 .1U 1000P .1U 1000P .1U .1U 100P .1U .01U .01U .1U .1U .1U .1U .1U .1U .1U 100P 2.2P .1U .1U .1U .1U .01U 100P 100P 4.7UF/50V .1U .1U 1000P 1000P .1U .1U 1000P .1U .01U .1U .047U .1U .1U 68P 100P 1000P 1000P 100P .015U .015U .1U Cap, Ceramic 50V SMT (1206) +/-10% X7R Capacitor, Chip (SMT1206), 50V, 5%, NPO Cap, Ceramic 50V SMT (1206) +/-10% X7R Capacitor, Chip (SMT1206), 50V, 5%, NPO SMT Film Capacitors, 50V, 5%, All Sizes Cap, Ceramic 50V SMT (1206) +/-10% X7R Capacitor, Chip (SMT1206), 50V, 5%, NPO SMT Film Capacitors, 50V, 5%, All Sizes SMT Film Capacitors, 50V, 5%, All Sizes SMT Film Capacitors, 50V, 5%, All Sizes Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R SMT Film Capacitors, 50V, 5%, All Sizes SMT Film Capacitors, 50V, 5%, All Sizes Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R Capacitor, Chip (SMT1206), 50V, 5%, NPO Capacitor, Chip (SMT1206), 50V, 5%, NPO Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R Capacitor, Chip (SMT1206), 50V, 5%, NPO Capacitor, Chip (SMT1206), 50V, 5%, NPO Cap, Tantalum, SMT (all case sizes) Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R Capacitor, Chip (SMT1206), 50V, 5%, NPO Capacitor, Chip (SMT1206), 50V, 5%, NPO Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R Capacitor, Chip (SMT1206), 50V, 5%, NPO SMT Film Capacitors, 50V, 5%, All Sizes Cap, Ceramic 50V SMT (1206) +/-10% X7R SMT Film Capacitors, 50V, 5%, All Sizes SMT Film Capacitors, 50V, 5%, All Sizes Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R Capacitor, Chip (SMT1206), 50V, 5%, NPO Capacitor, Chip (SMT1206), 50V, 5%, NPO Capacitor, Chip (SMT1206), 50V, 5%, NPO Capacitor, Chip (SMT1206), 50V, 5%, NPO Capacitor, Chip (SMT1206), 50V, 5%, NPO SMT Film Capacitors, 50V, 5%, All Sizes SMT Film Capacitors, 50V, 5%, All Sizes Cap, Ceramic 50V SMT (1206) +/-10% X7R PRS10 Rubidium Frequency Standard PRS10 Parts List REF. SRS PART VALUE DESCRIPTION C 422 C 423 C 424 C 425 C 426 C 427 C 428 C 429 C 430 C 431 C 432 C 433 C 434 C 436 C 437 C 438 C 439 C 440 C 500 C 502 C 504 C 506 C 507 C 508 C 509 C 510 C 511 C 512 C 513 C 514 C 515 C 516 C 517 C 518 C 519 C 520 C 521 C 600 C 601 C 602 C 700 C 800 C 801 C 802 C 803 C 804 C 805 C 900 5-00298-568 5-00299-568 5-00387-552 5-00387-552 5-00299-568 5-00375-552 5-00387-552 5-00298-568 5-00359-552 5-00356-552 5-00299-568 5-00364-552 5-00366-552 5-00299-568 5-00299-568 5-00466-572 5-00298-568 5-00466-572 5-00595-569 5-00595-569 5-00387-552 5-00595-569 5-00595-569 5-00595-569 5-00387-552 5-00356-552 5-00387-552 5-00299-568 5-00376-552 5-00299-568 5-00387-552 5-00299-568 5-00299-568 5-00299-568 5-00299-568 5-00299-568 5-00299-568 5-00299-568 5-00299-568 5-00299-568 5-00480-574 5-00299-568 5-00299-568 5-00387-552 5-00387-552 5-00299-568 5-00387-552 5-00100-517 .01U .1U 1000P 1000P .1U 100P 1000P .01U 4.7P 2.7P .1U 12P 18P .1U .1U .1U .01U .1U 2.2U/50V 2.2U/50V 1000P 2.2U/50V 2.2U/50V 2.2U/50V 1000P 2.7P 1000P .1U 120P .1U 1000P .1U .1U .1U .1U .1U .1U .1U .1U .1U 5.6P 500V .1U .1U 1000P 1000P .1U 1000P 2.2U Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R Capacitor, Chip (SMT1206), 50V, 5%, NPO Capacitor, Chip (SMT1206), 50V, 5%, NPO Cap, Ceramic 50V SMT (1206) +/-10% X7R Capacitor, Chip (SMT1206), 50V, 5%, NPO Capacitor, Chip (SMT1206), 50V, 5%, NPO Cap, Ceramic 50V SMT (1206) +/-10% X7R Capacitor, Chip (SMT1206), 50V, 5%, NPO Capacitor, Chip (SMT1206), 50V, 5%, NPO Cap, Ceramic 50V SMT (1206) +/-10% X7R Capacitor, Chip (SMT1206), 50V, 5%, NPO Capacitor, Chip (SMT1206), 50V, 5%, NPO Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R SMT Film Capacitors, 50V, 5%, All Sizes Cap, Ceramic 50V SMT (1206) +/-10% X7R SMT Film Capacitors, 50V, 5%, All Sizes Cap, Tantalum, SMT (all case sizes) Cap, Tantalum, SMT (all case sizes) Capacitor, Chip (SMT1206), 50V, 5%, NPO Cap, Tantalum, SMT (all case sizes) Cap, Tantalum, SMT (all case sizes) Cap, Tantalum, SMT (all case sizes) Capacitor, Chip (SMT1206), 50V, 5%, NPO Capacitor, Chip (SMT1206), 50V, 5%, NPO Capacitor, Chip (SMT1206), 50V, 5%, NPO Cap, Ceramic 50V SMT (1206) +/-10% X7R Capacitor, Chip (SMT1206), 50V, 5%, NPO Cap, Ceramic 50V SMT (1206) +/-10% X7R Capacitor, Chip (SMT1206), 50V, 5%, NPO Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R SMT, High Voltage Porcelain Cap. Cap, Ceramic 50V SMT (1206) +/-10% X7R Cap, Ceramic 50V SMT (1206) +/-10% X7R Capacitor, Chip (SMT1206), 50V, 5%, NPO Capacitor, Chip (SMT1206), 50V, 5%, NPO Cap, Ceramic 50V SMT (1206) +/-10% X7R Capacitor, Chip (SMT1206), 50V, 5%, NPO Capacitor, Tantalum, 35V, 20%, Rad 67 PRS10 Rubidium Frequency Standard 68 PRS10 Parts List REF. SRS PART VALUE DESCRIPTION C 903 C 904 C 905 C 906 D 100 D 101 D 102 D 202 D 203 D 204 D 205 D 400 D 401 D 500 D 501 D 502 D 503 D 504 D 700 J 100 J 100X J 400 J 700 J 701 J 800 J 801 J 802 JP500 JP501 L 100 L 101 L 102 L 103 L 104 L 105 L 200 L 300 L 301 L 302 L 400 L 401 L 402 L 403 L 902 LX104 LX105 P 100 PC1 5-00487-574 5-00479-574 5-00479-574 5-00487-574 3-00803-360 3-00648-360 3-00648-360 3-00538-360 3-00854-313 3-00854-313 3-00854-313 3-00803-360 3-00803-360 3-00648-360 3-00806-360 3-00649-360 3-00544-360 3-00806-360 3-00235-308 1-00319-166 1-00320-100 1-00224-141 1-00222-141 1-00222-141 6-00017-630 6-00017-630 6-00017-630 1-00323-130 1-00324-130 6-00171-606 6-00171-606 6-00264-609 6-00264-609 6-00174-630 6-00174-630 6-00236-631 6-00236-631 6-00236-631 6-00236-631 6-00530-609 6-00513-609 6-00266-609 6-00281-609 6-00011-603 0-00772-000 0-00772-000 4-01576-459 7-00767-701 68P 500V 18P 500V 18P 500V 68P 500V MMBV609 MBRD660CT MBRD660CT MMBD352L ZMM5230B ZMM5230B ZMM5230B MMBV609 MMBV609 MBRD660CT BAV170LT1 BAW56LT1 BAV70LT1 BAV170LT1 MP4025 10 PIN MALE COAX INSERT STRAIGHT PLUG REAR MT JACK REAR MT JACK FB43-301 FB43-301 FB43-301 64 PIN STRIP 64 HDR PIN R/A 4.7UH-5PH 4.7UH-5PH 100UH - SMT 100UH - SMT 6611 TYPE 43 6611 TYPE 43 FR47 FR47 FR47 FR47 .027UH - SMT .012UH - SMT .18UH - SMT 2.2U - SMT 1.0U 1.5" WIRE 1.5" WIRE 50K 9MM SIDE RB MULTIPLES SMT, High Voltage Porcelain Cap. SMT, High Voltage Porcelain Cap. SMT, High Voltage Porcelain Cap. SMT, High Voltage Porcelain Cap. Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Diode, SMT Diode, SMT Diode, SMT Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Diode, Step Recovery Connector, D-Sub, Male Connector, Misc. SMB Connector SMB Connector SMB Connector Ferrite Beads Ferrite Beads Ferrite Beads Connector, Male Connector, Male Inductor, Variable Inductor, Variable Inductor, Fixed, SMT Inductor, Fixed, SMT Ferrite Beads Ferrite Beads Ferrite bead, SMT Ferrite bead, SMT Ferrite bead, SMT Ferrite bead, SMT Inductor, Fixed, SMT Inductor, Fixed, SMT Inductor, Fixed, SMT Inductor, Fixed, SMT Inductor, Axial Hardware, Misc. Hardware, Misc. Pot, Multi-Turn Cermet, Various sizes Printed Circuit Board PRS10 Rubidium Frequency Standard PRS10 Parts List REF. SRS PART VALUE DESCRIPTION Q 100 Q 101 Q 150 Q 400 Q 500 Q 501 Q 502 Q 503 Q 504 Q 600 Q 800 Q 900 R 100 R 101 R 102 R 103 R 104 R 105 R 106 R 107 R 108 R 109 R 110 R 111 R 112 R 113 R 114 R 115 R 116 R 117 R 118 R 119 R 120 R 121 R 123 R 150 R 151 R 153 R 154 R 200 R 201 R 202 R 203 R 204 R 205 R 206 R 207 R 208 3-00808-360 3-00555-360 3-00325-329 3-00895-360 3-00807-360 3-00540-360 3-00808-360 3-00809-360 3-00810-360 3-00325-329 3-00325-329 3-00665-360 4-01242-462 4-01184-462 4-01309-462 4-00954-462 4-01280-462 4-01213-462 4-01447-461 4-01088-462 4-01184-462 4-01213-462 4-01184-462 4-01067-462 4-01447-461 4-01146-462 4-01096-462 4-01251-462 4-01251-462 4-01479-461 4-01503-461 4-01503-461 4-01503-461 4-01213-462 4-00925-462 4-01407-461 4-01407-461 4-00899-431 4-00899-431 4-01280-462 4-01305-462 4-01295-462 4-01213-462 4-01557-461 4-01575-461 4-01213-462 4-01376-462 4-01230-462 MMBR5179 MMBR941L TIP107 NE461M02 MJD47 MMBT5087 MMBR5179 MMBTH81LT1 MMBTH10LT1 TIP107 TIP107 MRF134 20.0K 4.99K 100K 20 49.9K 10.0K 47 499 4.99K 10.0K 4.99K 301 47 2.00K 604 24.9K 24.9K 1.0K 10K 10K 10K 10.0K 10 1 1 P1H104-T-NTC P1H104-T-NTC 49.9K 90.9K 71.5K 10.0K 1.8M 10M 10.0K 499K 15.0K Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Voltage Reg., TO-220 (TAB) Package Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Voltage Reg., TO-220 (TAB) Package Voltage Reg., TO-220 (TAB) Package Integrated Circuit (Surface Mount Pkg) Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thermistor, various Thermistor, various Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor 69 PRS10 Rubidium Frequency Standard 70 PRS10 Parts List REF. SRS PART VALUE DESCRIPTION R 209 R 210 R 211 R 213 R 214 R 215 R 216 R 217 R 218 R 219 R 220 R 221 R 222 R 223 R 224 R 226 R 227 R 228 R 229 R 230 R 231 R 232 R 233 R 234 R 235 R 236 R 237 R 238 R 240 R 241 R 248 R 249 R 250 R 252 R 256 R 261 R 262 R 263 R 264 R 265 R 266 R 267 R 268 R 269 R 270 R 271 R 272 R 273 4-01280-462 4-01230-462 4-01278-462 4-01280-462 4-01305-462 4-01309-462 4-01213-462 4-01557-461 4-01575-461 4-01213-462 4-01376-462 4-01230-462 4-01280-462 4-01230-462 4-01278-462 4-01238-462 4-01305-462 4-01363-462 4-01213-462 4-01557-461 4-01575-461 4-01213-462 4-01309-462 4-01376-462 4-01251-462 4-01280-462 4-01251-462 4-01278-462 4-01479-461 4-01117-462 4-01439-461 4-01059-462 4-01479-461 4-01479-461 4-01503-461 4-01335-462 4-01355-462 4-01309-462 4-01309-462 4-01098-462 4-01309-462 4-01309-462 4-01405-462 4-01280-462 4-01347-462 4-01213-462 4-01280-462 4-01455-461 49.9K 15.0K 47.5K 49.9K 90.9K 100K 10.0K 1.8M 10M 10.0K 499K 15.0K 49.9K 15.0K 47.5K 18.2K 90.9K 365K 10.0K 1.8M 10M 10.0K 100K 499K 24.9K 49.9K 24.9K 47.5K 1.0K 1.00K 22 249 1.0K 1.0K 10K 187K 301K 100K 100K 634 100K 100K 1.00M 49.9K 249K 10.0K 49.9K 100 Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor PRS10 Rubidium Frequency Standard PRS10 Parts List REF. SRS PART VALUE DESCRIPTION R 274 R 275 R 276 R 277 R 278 R 279 R 280 R 281 R 282 R 283 R 284 R 285 R 286 R 287 R 288 R 289 R 290 R 291 R 292 R 293 R 294 R 295 R 296 R 297 R 298 R 299 R 300 R 301 R 303 R 304 R 305 R 324 R 325 R 326 R 327 R 329 R 331 R 332 R 333 R 334 R 335 R 336 R 337 R 338 R 339 R 340 R 341 R 342 4-01191-462 4-01213-462 4-01305-462 4-01213-462 4-01305-462 4-01213-462 4-01305-462 4-01213-462 4-01305-462 4-01213-462 4-01294-462 4-01280-462 4-01294-462 4-01280-462 4-01294-462 4-01280-462 4-01479-461 4-01575-461 4-01479-461 4-01213-462 4-01251-462 4-01575-461 4-01213-462 4-01280-462 4-01213-462 4-01280-462 4-01405-462 4-01302-462 4-01479-461 4-01479-461 4-01527-461 4-01249-462 4-01230-462 4-01213-462 4-01455-461 4-01455-461 4-01073-462 4-01117-462 4-01405-462 4-01251-462 4-01213-462 4-01575-461 4-01455-461 4-01503-461 4-01479-461 4-01479-461 4-01503-461 4-01479-461 5.90K 10.0K 90.9K 10.0K 90.9K 10.0K 90.9K 10.0K 90.9K 10.0K 69.8K 49.9K 69.8K 49.9K 69.8K 49.9K 1.0K 10M 1.0K 10.0K 24.9K 10M 10.0K 49.9K 10.0K 49.9K 1.00M 84.5K 1.0K 1.0K 100K 23.7K 15.0K 10.0K 100 100 348 1.00K 1.00M 24.9K 10.0K 10M 100 10K 1.0K 1.0K 10K 1.0K Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor 71 PRS10 Rubidium Frequency Standard 72 PRS10 Parts List REF. SRS PART VALUE DESCRIPTION R 343 R 344 R 345 R 346 R 347 R 348 R 349 R 350 R 351 R 352 R 353 R 354 R 355 R 356 R 357 R 358 R 359 R 360 R 400 R 401 R 402 R 403 R 404 R 405 R 406 R 407 R 408 R 409 R 410 R 411 R 412 R 413 R 414 R 415 R 416 R 417 R 418 R 419 R 420 R 421 R 422 R 423 R 424 R 425 R 426 R 427 R 428 R 429 4-01503-461 4-01464-461 4-01464-461 4-01464-461 4-01464-461 0-00000-000 4-01464-461 4-01464-461 4-01464-461 4-01464-461 0-00000-000 4-01493-461 4-01527-461 4-01493-461 4-01527-461 0-00000-000 0-00000-000 4-01213-462 4-01347-462 4-01405-462 4-01447-461 4-01463-461 4-01527-461 4-01201-462 4-01561-461 4-01213-462 4-01259-462 4-01355-462 4-01309-462 4-01527-461 4-01088-462 4-01088-462 4-01088-462 4-01251-462 4-01251-462 4-01117-462 4-01117-462 4-01467-461 4-01467-461 4-01088-462 4-01355-462 4-01309-462 4-01479-461 4-01471-461 4-01479-461 4-01479-461 4-01447-461 4-01503-461 10K 240 240 240 240 UNDECIDED PART 240 240 240 240 UNDECIDED PART 3.9K 100K 3.9K 100K UNDECIDED PART UNDECIDED PART 10.0K 249K 1.00M 47 220 100K 7.50K 2.7M 10.0K 30.1K 301K 100K 100K 499 499 499 24.9K 24.9K 1.00K 1.00K 330 330 499 301K 100K 1.0K 470 1.0K 1.0K 47 10K Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Hardware, Misc. Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Hardware, Misc. Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Hardware, Misc. Hardware, Misc. Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor PRS10 Rubidium Frequency Standard PRS10 Parts List REF. SRS PART VALUE DESCRIPTION R 430 R 431 R 432 R 433 R 434 R 435 R 436 R 437 R 438 R 439 R 440 R 441 R 442 R 443 R 444 R 445 R 446 R 447 R 448 R 449 R 450 R 500 R 501 R 502 R 503 R 504 R 505 R 506 R 507 R 508 R 509 R 510 R 511 R 512 R 513 R 514 R 515 R 516 R 517 R 518 R 519 R 520 R 521 R 522 R 523 R 524 R 525 R 526 4-01280-462 4-01117-462 4-01447-461 4-01447-461 4-01447-461 4-01213-462 4-01280-462 4-01503-461 4-01355-462 4-01309-462 4-01280-462 4-01213-462 4-01184-462 4-01439-461 4-00992-462 4-01511-461 4-01503-461 4-01455-461 4-01447-461 4-01551-461 4-01439-461 4-01059-462 4-01021-462 4-01280-462 4-01213-462 4-00925-462 4-00925-462 4-01213-462 4-01213-462 4-01309-462 4-01309-462 4-01347-462 4-01280-462 4-01479-461 4-01059-462 4-01167-462 4-01487-461 4-01213-462 4-01405-462 4-01242-462 4-01146-462 4-01088-462 4-01230-462 4-01117-462 4-01251-462 4-01447-461 4-01479-461 4-01242-462 49.9K 1.00K 47 47 47 10.0K 49.9K 10K 301K 100K 49.9K 10.0K 4.99K 22 49.9 22K 10K 100 47 1.0M 22 249 100 49.9K 10.0K 10 10 10.0K 10.0K 100K 100K 249K 49.9K 1.0K 249 3.32K 2.2K 10.0K 1.00M 20.0K 2.00K 499 15.0K 1.00K 24.9K 47 1.0K 20.0K Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor 73 PRS10 Rubidium Frequency Standard 74 PRS10 Parts List REF. SRS PART VALUE DESCRIPTION R 527 R 528 R 529 R 530 R 531 R 532 R 533 R 534 R 536 R 537 R 538 R 539 R 540 R 541 R 542 R 543 R 544 R 545 R 546 R 547 R 548 R 550 R 551 R 552 R 553 R 600 R 601 R 602 R 603 R 604 R 605 R 800 R 801 R 803 R 804 R 900 T 100 U 100 U 101 U 102 U 150 U 200 U 201 U 202 U 205 U 206 U 207 U 208 4-01230-462 4-01213-462 4-01213-462 4-01213-462 4-01213-462 4-01213-462 4-01493-461 4-01213-462 4-01213-462 4-01213-462 4-01213-462 4-01489-461 4-01184-462 4-01184-462 4-01184-462 4-01146-462 4-01218-462 4-01117-462 4-01146-462 4-01447-461 4-01469-461 4-01405-462 4-01479-461 4-00925-462 4-00925-462 4-01407-461 4-01407-461 4-01407-461 4-00899-431 4-00899-431 4-01407-461 4-01407-461 4-01407-461 4-00899-431 4-00899-431 4-01597-405 6-00195-610 3-00542-360 3-00819-360 3-00773-360 3-00346-329 3-00774-360 3-00774-360 3-00774-360 3-00653-360 3-00659-360 3-00774-360 3-00661-360 15.0K 10.0K 10.0K 10.0K 10.0K 10.0K 3.9K 10.0K 10.0K 10.0K 10.0K 2.7K 4.99K 4.99K 4.99K 2.00K 11.3K 1.00K 2.00K 47 390 1.00M 1.0K 10 10 1 1 1 P1H104-T-NTC P1H104-T-NTC 1 1 1 P1H104-T-NTC P1H104-T-NTC 10K 10.7 MHZ AD587JR LM7171AIM LM358 7812 LMC662C LMC662C LMC662C AD8561AR OP284FS LMC662C 74HC4051 Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thin Film, 1%, 50 ppm, MELF Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thermistor, various Thermistor, various Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thick Film, 5%, 200 ppm, Chip Resistor Thermistor, various Thermistor, various Resistor, Carbon Film, 1/8W, 5% Transformer Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Voltage Reg., TO-220 (TAB) Package Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) PRS10 Rubidium Frequency Standard PRS10 Parts List REF. SRS PART VALUE DESCRIPTION U 209 U 210 U 300 U 301 U 303 U 304 U 306 U 307 U 308 U 309 U 310 U 311 U 312 U 313 U 314 U 400 U 401 U 402 U 403 U 404 U 405 U 406 U 407 U 500 U 501 U 502 U 503 U 504 U 505 U 506 U 507 U 508 U 509 U 510 U 511 U 512 U 514 U 600 U 800 Y 100 Y 400 Z0 Z0 Z0 Z0 Z0 Z0 Z0 3-00661-360 3-00581-360 3-00563-360 3-00662-360 3-00663-360 3-00662-360 3-00643-360 3-00773-360 3-00659-360 3-00581-360 3-00652-360 3-00652-360 3-00652-360 3-00652-360 3-00658-360 3-00946-360 3-00581-360 3-00654-360 3-00660-360 6-00193-625 3-00650-360 3-00773-360 3-00655-360 3-00751-360 3-00149-329 3-00581-360 3-00149-329 3-00112-329 3-00775-360 3-00742-360 3-00742-360 3-00742-360 3-00813-360 3-00812-360 3-00581-360 3-00581-360 3-00534-360 3-00346-329 3-00561-329 6-00132-620 6-00194-620 0-00045-013 0-00096-041 0-00098-042 0-00231-043 0-00243-003 0-00605-025 0-00606-025 74HC4051 AD822 MAX705CSA 74HC14 74HC08 74HC14 DG211BDY LM358 OP284FS AD822 LTC1452CS8 LTC1452CS8 LTC1452CS8 LTC1452CS8 AD7896AR MC145193F AD822 SA602D OP27GS 380 MHZ MC12026AD LM358 TLC5628 74HC574 LM317T AD822 LM317T 7805 LM45CIM3 74HC74 74HC74 74HC74 LM311M 74HC153 AD822 AD822 AD790JR 7812 7808 10 MHZ SC-CUT 22.4825 MHZ 4-40 MINI #4 SPLIT #6 LOCK 1-32, #4 SHOULD TO-220 4-40X1/4 SOCKET 4-40X1/4 BUTTON Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Voltage Controlled Crystal Oscillator Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Voltage Reg., TO-220 (TAB) Package Integrated Circuit (Surface Mount Pkg) Voltage Reg., TO-220 (TAB) Package Voltage Reg., TO-220 (TAB) Package Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Integrated Circuit (Surface Mount Pkg) Voltage Reg., TO-220 (TAB) Package Voltage Reg., TO-220 (TAB) Package Crystal Crystal Nut, Mini Washer, Split Washer, lock Washer, nylon Insulators Screw, Allen Head Screw, Allen Head 75 PRS10 Rubidium Frequency Standard 76 PRS10 Parts List REF. SRS PART VALUE DESCRIPTION Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 0-00607-025 0-00608-025 0-00609-025 0-00629-066 0-00630-034 0-00641-031 0-00642-031 0-00643-020 0-00644-020 0-00645-055 0-00902-034 0-00908-030 0-00915-034 1-00323-130 1-00324-130 3-00668-312 7-00557-717 7-00560-721 7-00636-720 7-00638-721 7-00639-721 7-00641-721 7-00862-720 9-00571-924 4-40X1/2 SOCKET 6-32X1/4 BUTTON 6-32X5/8 SOCKET FOIL;CU 1/2" #22 INSULATING 4-40X3/16 M/F 4-40X3/8 M/F 4-40X3/16PF UND 4-40X1/4PF UNDR #34AWG MAGNET S/S SEAMLESS PROTO MATERIAL CU TUBING 1/16 64 PIN STRIP 64 HDR PIN R/A PHOTODIODE RB-10 RB-1 RB-4 RB-6 RB-7 RB-9 RB SPACER SPECIALTY #56 Screw, Allen Head Screw, Allen Head Screw, Allen Head Copper Foil Tape, Self Adhesive Tubing Standoff Standoff Screw, Flathead Phillips Screw, Flathead Phillips Wire, Other Tubing Spacer Tubing Connector, Male Connector, Male Photodiode Deep-Drawn or Stamping Machined Part Fabricated Part Machined Part Machined Part Machined Part Fabricated Part Tape, All types Miscellaneous Parts List REF. SRS PART VALUE DESCRIPTION R 901 U 302 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 4-01620-409 3-00646-360 0-00096-041 0-00602-060 0-00606-025 0-00628-065 0-00644-020 0-00659-044 0-00668-025 0-00669-025 0-00670-025 1-00355-150 6-00505-600 7-00556-717 7-00637-720 7-00640-720 7-00764-720 9-00805-917 536-2W 68HC711E20CFN #4 SPLIT 4-40X3/32 SET 4-40X1/4 BUTTON 4-40X10-32X1/4" 4-40X1/4PF UNDR LAMP WINDOW 4-40X3/16 HEX 4-40X5/16 HEX 4-40X3/8 BUTTON LAMP RB CLOCK RB-12 RB-5 RB-8 RB-15 RUBIDIUM SERIAL Resistor, Wire Wound Integrated Circuit (Surface Mount Pkg) Washer, Split Screw, Misc Screw, Allen Head Inserts, Threaded Screw, Flathead Phillips Window Screw, Allen Head Screw, Allen Head Screw, Allen Head Socket, THRU-HOLE Misc. Components Deep-Drawn or Stamping Fabricated Part Fabricated Part Fabricated Part Product Labels PRS10 Rubidium Frequency Standard PRS10 Parts List 77 4.00 3.60 2.00 0.20 TYP. 3.00 2.60 BOTTOM VIEW BASEPLATE 0.144 MOUNTING PLATE 1.637 END VIEW 10 7 0.30 6 1 FREQUENCY ADJUSTMENT 1.03 MOUNTING HOLES #4-40 UNC-2B x 0.25 DEEP (4 PLACES) CONNECTOR MATES WITH 1. POSITRONIC CBM11W1F2 WITH COAX INSERT MS4104D 2. CANNON DAM11W1S WITH COAX INSERT DM53740-5000 NOTE: ALL DIMENSIONS IN INCHES. Figure 4. Mechanical Dimensions PRS10 Rubidium Frequency Standard
Source Exif Data:
File Type : PDF File Type Extension : pdf MIME Type : application/pdf PDF Version : 1.5 Linearized : No Modify Date : 2005:11:10 13:53:49-08:00 Create Date : 2002:05:09 12:59:23Z Page Count : 115 Has XFA : No About : uuid:7013eb44-814c-4d9f-af8a-909815a2590f Producer : Acrobat Distiller 4.05 for Windows Mod Date : 2005:11:10 13:53:49-08:00 Creation Date : 2002:05:09 12:59:23Z Metadata Date : 2005:11:10 13:53:49-08:00 Document ID : uuid:1a961ef3-aa0a-4839-8b85-c3d4b81455d0 Format : application/pdfEXIF Metadata provided by EXIF.tools