Hitachi Kokusai Electric America AT7120 120 Watt UHF ATSC Transmitter User Manual 2
Hitachi Kokusai Electric America LTD 120 Watt UHF ATSC Transmitter 2
Exhibit D Users Manual per 2 1033 c3
AT7120 Owner Manual Rev. 1.1 – March 2009 2/76
AT7120
120W UHF 8VSB-ATSC TRANSMITTER
ADVANCED TV LINE
Owner Manual
Table of Contents
User Notices and WARNINGS .................................................................................................. 3
Section 1 – AT7120 General Description................................................................................... 6
Section 2 – Control Set ............................................................................................................ 15
Section 3 – 8VSB Modulator and Master Clock ....................................................................... 22
Section 4 – IF/UHF up-converter ............................................................................................. 26
Section 5 – UHF ATSC Exciter ................................................................................................ 31
Section 6 – UHF ATSC Amplifier ............................................................................................. 35
Section 7 – Power Supply ........................................................................................................ 40
Section 8 – DC/DC Converter .................................................................................................. 47
Section 9 – Memory Interface .................................................................................................. 48
Annex A – AT7120 Operational Software ................................................................................ 49
Annex B – Checking the RF Power LDMOS Transistors ......................................................... 72
Annex C – Typical Final Test Reports Results ........................................................................ 73
AT7120 Owner Manual Rev. 1.1 – March 2009 3/76
User Notices and WARNINGS
USER NOTICES
IT IS VERY IMPORTANT TO READ THE FOLLOWING MANUAL SECTIONS PRIOR TO
OPERATION OF THIS TRANSMITTER!
Notice 1
The transmitter main operating voltage setting is marked on the rear of the chassis.
Notice 2
The transmitter operating frequency is set from the factory.
Notice 3
For adjusting the RF output power setting a qualified technician should always employ the use of an RF
Wattmeter and a calibrated dummy load.
Notice 4
Should accident or injury occur to the personnel engaged in the installation, operation, or service of the
equipment should seek proper medical attention. It is advisable that such personnel have familiarity
with first-aid practices.
Notice 5
To call our technical support center or for other customer service issues at Linear Inc, refer to the
following number: 847 428-5793, or e-mail to broadcast@linear-tv.com
Notice 6
If you experience some specific difficulty and the technical information available in this manual is not
enough to help you, do not hesitate to call LINEAR technical support center.
Notice 7
The technical information presented on this manual is sole intellectual propriety of LINEAR
INDUSTRIES Inc. Reproduction of this document in full or partial is prohibiting without written
authorization. This document is legally protected by the copy rights laws.
WARNING!
THE VOLTAGES AND CURRENTS IN THIS EQUIPMENT COULD BE DANGEROUS. PERSONEL
MUST, AT ALL TIMES, OBSERVE SAFETY WARNINGS, INSTRUCTIONS, AND ANY
REGULATIONS.
AT7120 Owner Manual Rev. 1.1 – March 2009 4/76
THIS OWNER’S MANUAL IS INTENDED AS A GENERAL GUIDE FOR TRAINED AND
QUALIFIED PERSONNEL WHO ARE AWARE OF THE DANGERS THAT ARE INHERENT IN
THE HANDLING AND OPERATION OF POTENTIALLY HAZARDOUS ELECTRICAL AND
ELECTRONIC CIRCUITS. IT IS NOT THE INTENT OF THIS MANUAL TO PROVIDE A
COMPLETE SET OF SAFETY INSTRUCTIONS OR PRECAUTIONS THAT SHOULD ALREADY
BE UNDERSTOOD BY TRAINED OR EXPERIENCED PERSONNEL IN USING THIS OR OTHER
TYPES OF ELECTRONIC EQUIPMENT.
THE INSTALLATION, OPERATION, AND MAINTENANCE OF THIS EQUIPMENT INVOLVE
RISKS TO PERSONNEL AND ALSO TO THE EQUIPMENT. LINEAR, INC. SHALL NOT BE
RESPONSIBLE FOR INJURY OR DAMAGE THAT IS THE RESULT OF IMPROPER
PROCEDURES OR USE BY PERSONS IMPROPERLY TRAINED OR LACKING THE
KNOWLEDGE TO PERFORM ASSOCIATED TASKS.
ALL LOCAL CODES FOR BUILDING, SAFETY, FIRE, OR RELATED STANDARDS MUST BE
OBSERVED. CONSULT LOCAL AUTHORITIES FOR THE STANDARDS FOR THE AREA OR
REGION WHERE THE EQUIPMENT WILL BE INSTALLED AND PUT IN USE.
WARNING!
AT ALL TIMES DISCONNECT AC/MAINS POWER BEFORE OPENING COVERS, DOORS,
ENCLOSURES, PANELS, OR PROTECTIVE SHIELDS THAT EXPOSE LIVE CIRCUITS. NEVER
PERFORM MAINTENANCE, MAKE ADJUSTMENTS, OR SERVICE THE EQUIPMENT WHEN
ALONE OR FATIGUED.
WARNING!
IF ELECTROLYTIC OR OIL FILLED CAPACITORS ARE UTILIZED IN THE EQUIPMENT AND
THE COMPONENT APPEARS LEAKY, OR IS BULGING, OR IF THE CASE OR COVERING OF
THE COMPONENT APPEARS DAMAGED OR DISTRESSED ALLOW SUFFICIENT TIME FOR
THE UNIT TO COOL and FULLY DISCHARGE BEFORE SERVICING. SERVICING HOT OR
LEAKY CAPACITORS CAN CAUSE A RUPTURE OF THE CASE AND POSSIBLE INJURY.
Returns and Exchanges
Equipment (Damaged or undamaged) should not be returned without written approval and a
Merchandise Return Authorization (MRA Number) from your Linear Sales representative or Linear
Customer Service. Special shipping instruction will be provided which will assure proper handling.
The circumstances and reasons for the return must be included in the request for return. Equipment that
is special or “custom” ordered may not be returnable. In situations where return or exchange is at the
request of the customer a restocking fee may be charged. All returns must be sent freight prepaid and
AT7120 Owner Manual Rev. 1.1 – March 2009 5/76
properly insured by customer. When communicating with Linear please refer to your Order or Invoice
Number.
Unpacking
Use care when unpacking the equipment. First perform a visual inspection of the item(s) to determine if
any damage occurred during shipment. Be sure to retain all the shipping materials (crates and boxes or
cartons) until such time that it has been determined that the received equipment arrived undamaged.
Find all PACKING LISTS and keep them to assist in locating and identifying any components or
assemblies that may have been removed for safe. Make sure that all shipping straps, supports and
packing materials are completely removed from the equipment prior to initialization and use.
AT7120 Owner Manual Rev. 1.1 – March 2009 6/76
Section 1 – AT7120 General Description
The ATSC DTV transmitter model AT7120 is part of the ADVANCED TV line, having modular
construction meeting EIA 19”rack standards, and is composed for the following modules:
01 Main Control unit - CIM3297
01 Keypad - CIM3003
01 Display LCD 20 columns x 02 lines - CIM3004
01 Memory interface - CIP8421
01 1Mbits memory card – CIP8421
01 UHF ATSC Exciter- Module 4407
01 up-Digital Converter - Module 4492
01 Power Supply - Module 4401 (versions M110/M220/B220)
01 8VSB Modulator and Master Clock Generator - Module 4549
01 DC/DC Converter (+2.5V and +5V) – Module 4567
02 UHF ATSC Amplifier – Module 4442
01 OCXO – Module 4292
When AT7120 is a TRANSMITTER that can be installed with or without a 6 pole elliptical filter on its
RF output. In this application, the overall performance of the unit will meet or exceed the FCC
requirements for out of channel spurious emission. Please refer to Annex C.
AT7120 Owner Manual Rev. 1.1 – March 2009 7/76
AT7120 Block Diagram
+28V
RELIGADO
UHF ATSC EXCITER
MODULE 4407
+8V +15V
KEYBOARD
CIM3003
LINEAR EQUIPAMENTOS ELETRÔNICOS
DISPLAY
CIM3004
RESTART
RFOUT
ALARME DE
TEMPERATURA LEITURA DE
POTÊNCIA DIRETA
FAN
FILTER FAN
CIM6646 +24V
IN OUT
EXC.TEMPERATURE
PA1 TEMPERATURE
PA2 TEMPERATURE
ALARMS
SHUT DOWN 1
CONTROL UNIT
CIM3297
(CIP8231)
MAIN POWER SUPPLY
MODULE 4401
ID
CURRENT
READING +28V
READING +18V
READING -18V
READING +9V
READING
+18V-18V
+9V
+28V
FIXO
+28V
RES.
1 SUBORDINATE
POWER SUPPLY
MODULE 4402
SHUT DOWN 1
+28V
FIXO
AC FAN
+32V
(VA) +32V
(VB) TEMP
PA 1 PA1
TEMP
ALARM
ID1
READ ID2
READ
+28V
FIXO
UHF ATSC
AMPLIFIER
PA1
MODULE 4442
IN OUT
+32V
(VA) +32V
(VB)
1 SUBORDINATE
POWER SUPPLY
PA1
TEMP
8VSB
MODULATOR AND
MASTER CLOCK UHF UPCONVERTER
MODULE 4492
+18V-18V
RFOUT
SW2
TEMP
ENABLE Q DAC
ENABLE I DAC
CLOCK DAC
DATA DAC
ALC
+28V
FIXO
CLOCK PLL
LOCK DETECT
MODULE 4549
+5V+2.5V +18V-18V
10MHz
OCXO
MODULE 4281
RD
ENA
CLK
DIN
DO
LD
CONTROL UNIT
+28V
MODULE 4567
DC CONVERTER
+5V+2.5V
MEMORY
MEMORY
CARD
CARD
CIP8421
CIP8421
MEMORY INTERFACE
MEMORY INTERFACE
CIP8437
CIP8437
DCLK
ASDI
CS
DATA
FROM
CONTROL
UNIT
110 / 220V
MONOPHASIC / BIPHASIC
ON/OFF
SWITCH
5A / 220V
10A / 110V
FUSE
FUSE 5A / 220V
10A / 110V
120Wrms
RF OUT
RF
PW REF
PW
+15V
REFLT
IN OUT
MODULE
4166
FPB
MODULE
4252
310M IN
ASI IN
EXT. REF. IN
EXCITER FORWARD POWER
FORWARD POWER
REFLECTED POWER
I1 MAIN POWER SUPPLY
PA1 CURRENT ID1
PA1 CURRENT ID2
PA2 CURRENT ID3
PA2 CURRENT ID4
+28V MAIN POWER SUPPLY
+18V MAIN POWER SUPPLY
-18V MAIN POWER SUPPLY
+9V MAIN POWER SUPPLY
+32V 1 SUBORDINATE POWER SUPPLY
+32V 2 SUBORDINATE POWER SUPPLY
READINGS
MASTER CLOCK LOCK DETECT
+5V
QIN
IIN
+32V
READ
ENABLE
DATA PLL
SW1
DCLK
ASDI
CS
DATA
TO MEMORY
INTERFACE
RD
ENA
CLOCK
DIN
DO
LD
MODULATOR
÷
OUT 1
OUT 2
IN
MODULE 4442
IN OUT
+32V
(VA) +32V
(VB)
2 SUBORDINATE
POWER SUPPLY
PA2
TEMP
UHF ATSC
AMPLIFIER
PA2
Σ
IN 1
IN 2
OUT
2 SUBORDINATE
POWER SUPPLY
MODULE 4402
SHUT DOWN 2
+28V
FIXO
+32V
(VA) +32V
(VB) TEMP
PA 2 PA2
TEMP
ALARM
ID3
READ ID4
READ +32V
READ
AC FAN
SHUT DOWN 2
RS232
TELESUPERVISION
CONTROL
UNIT
AT7120 Owner Manual Rev. 1.1 – March 2009 8/76
Module 4549
8VSB Modulator
The 8VSB modulator automatically recognizes the incoming transport stream as either SMPTE310M or
ASI. The transport stream input utilizes the BNC connector located on the rear panel of the unit. The
modulated output signal of this module is composed by two IF orthogonal carriers termed; signals (I)
and (Q). The central frequency of the 8VSB modulated IF signal is 18.83339MHz. The signal
processing and modulation performed on this module follows the ATSC recommendation A/53 E.
This module also performs the non-linear corrections that might be necessary to enhance the equipment
efficiency to meet FCC spurious emissions requirements. In this case, an RF output filter is required.
The recommended linear equalization is also automatically performed in this module.
Master Clock
The master clock unit generates signals utilizing a Voltage Controlled Oscillator and Phase Locked
Loop at 172.16MHz. The PLL is locked at 10MHz reference, externally or internally generated. This
signal provides the time base for the 8VSB modulator.
Module 4492
IF to UHF up-Converter
The IF carries the orthogonal (I) and (Q) signals generated in module 4549, (8VSB Modulator), which is
then routed to the up-converter module. The output signal of this module is set on the FCC/UHF
operational 6MHz channel of the transmitter AT7120.
Inside the converter the modulated IF band is mixed with the continuous wave local oscillator LO. As a
result of this mixing, the IF translation to the UHF band is performed. The LO is a free oscillator, that
has its frequency locked via PLL. The LO/PLL is generated by a 10MHz OCXO (oven controlled
crystal oscillator), or provided by an external reference signal.
Module 4281
10MHz reference automatic switching
Both circuits; the 8VSB modulator and the up-converter, share the same reference signal source. The use
of the same reference signal creates perfect synchronization and stability during the DTV transmission
process. The internal 10MHz signal is obtained from an OCXO oscillator with a stability of 0.3ppm. An
external 10MHz signal can be used as the reference signal; a GPS signal for instance. The external
reference input is a BNC connector located on the rear panel of the unit. In the absence of this external
source, the unit automatically utilizes the internal 10MHz source generated by the OCXO.
AT7120 Owner Manual Rev. 1.1 – March 2009 9/76
Module 4407
60W UHF band multistage amplifier
The IF modulated signal (previously converted into UHF) is amplified by a 60W UHF amplifier. This
amplifier uses transistors built with LDMOS technology operating in a class AB configuration, which
provides excellent efficiency and linearity. The RF OUT connector of the unit provides the high power
RF output.
RF Output monitoring
Module 4407 detects the direct and reverse RF power present on the RF OUT connector of the unit. The
detected information is then converted to correspondent DC levels before being routed to the master
control unit, where it is processed and displayed at the front panel LCD screen in watts.
Module 4442
AT7120 transmitter has two Modules 4442 connected in parallel, which work as digital TV end
amplifiers in all UHF band. The amplifier is made of the following components:
Input Coupler
The input RF coupler equally divides the UHF signal present in the input connector for the two
amplification cells, maintaining 50Ω impedance.
Cell A – 35W Amplifier
The amplification cell A is obtained by a Push-Pull 35W amplifier, class AB. Transistor T1 is in this
cell. The polarization circuit of cell A is made of a VGS timer circuit with temperature compensation,
differential amplifier and gate impedance reducer.
Cell B – 35W Amplifier
Just as cell A, cell B’s amplification is obtained by a Push-Pull 35W amplifier, class AB. Transistor T2 is in this
cell. The polarization circuit in cell B also is made of a VGS timer circuit with temperature compensation,
differential amplifier and gate impedance reducer.
Output Coupler
It is a hybrid coupler built with a special semi-rigid coaxial cable, better known as “wireline”. This type
of cable has 2 internal conductors interlinked; this set has the characteristics of a hybrid coupler. As the
input coupler, this coupler also has four gates (input/output; isolated, -3dB 0˚, -3 dB 90˚).
Temperature Alarm
Module 4442 has a protection circuit that disarms the module in case the temperature rises above 65˚ C.
This circuit is basically made of thermal sensor S1, DC amplifier and voltage comparator CI-1.
AT7120 Owner Manual Rev. 1.1 – March 2009 10/76
CIM3297
Control unit card
The digital management of the DTV AT7120 transmitter is done by the control unit card, CIM3297.
This control unit uses an A128 microcontroller programmed in assembler language. The unit process
data regarding the following operational parameters:
Warns of signal lock failure of the PLL in the up-converter.
Warns of excessive temperature of the 60W amplifier.
Monitors and displays the RF direct and reflected powers of the 60W amplifier, muting the transmission
in case of extreme levels.
Displays DC current levels of the main power supply module.
Process and displays power supply voltage(s).
Sets in the operational channel of the Up-converter unit and transmits power levels via ALC. Sets and
monitors the operational channel frequency in the up-converter unit as well as the transmit power levels
which is controlled by the automatic level control circuits.
The control unit is directly connected to a keypad and LCD screen, both located on the front panel of the
transmitter AT7120. Numerous parameters can be set via the keypad and monitored by the LCD screen.
The same functions can be performed via RS232 HyperTerminal connection.
Module 4401
Power Supply
The power supply module is a switching power supply type, utilizing a half-bridge topology. A control unit
monitors the power supply output and adjusts to varying load to maintain a nominal +32 VDC. The voltage and
current data is provided to the control unit card for display on the LCD screen.
AT7120 Owner Manual Rev. 1.1 – March 2009 11/76
AT7120 External Interfaces
Fig.1.2: AT7120 Front View
AT7120 Owner Manual Rev. 1.1 – March 2009 12/76
Fig.1.3: AT7120 Rear Panel View
Power Switch
ID Tag
External 10MHz
Reference Input
Main Fuse
ASI/SMPTE310M Transport
Stream Input
AC Power Cord
(DB-9) RS232
Hyper-terminal Interface
Hot Air Outlets
GND
RF Output
Connector
Internal DB-9
Not Used
AT7120 Owner Manual Rev. 1.1 – March 2009 13/76
AT7120 - Modules and Parts Displacement
Fig.1.4: AT7120 Modules and Parts displacement
Key Pad
CIM3003
RF Power Amplifier
Module 4407
LCD Screen
CIM3004
Memory Card &
Interface
CIP 8437
DC/DC
Converter
Module 4567
DC Fan Filter
CIM6646
Digital Control Card
CIM3297/CIP8231A
+32V Power
Supply Module
4401
Ref. 10MHz OCXO
Module 4281
Power Switch
Fuse & GND
Up Converter
Module 4492
8VSB Modulator &
Master Clock
Module 4549
AT7120 Owner Manual Rev. 1.1 – March 2009 14/76
AT7120 - 120W ATSC UHF Transmitter - Technical
Specifications
Table XX: AT7120 Technical specifications
Electrical
Main
220 VAC, bi phase, 50-60 Hz. standard
Consumption
400W @ 120W RMS/RF
Power Factor Correction, FPC.
Included
Signal Input
Transport Stream Input
ATSC/MPEG2, compliant to
SMPTE310M
Input Data Rate
19.39 Mbps
External Reference Signal
10MHz. (0 to +10 dBm).
Input Connector
75Ω (BNC),
Reference Input Connector
50Ω (BNC),
RF
Modulation Mode
8VSB.
IF
18.833916 MHz.
Channel Bandwidth
6MHz.
Test Signal
PRBS
Frequency Range
UHF. C14 to Ch53, (3 bands).
Frequency Step
1 Hz. ± 220kHz
Symbol Rate
10.76 MSymbol/sec.
Digital/Analog Converter
16 bit
Linearization Pre-Correction
Included
Pilot frequency stability overall
± 4.6 ppm.
Initial tolerance
± 1.0 ppm.
Vs. temperature in operating temperature range (steady
state)
± 10 ppb.
Holdover 24 hours, full temp. range
± 12 ppb.
24 hours drift (after 30 days)
± 1.0 ppb.
Long term stability over 15 years
± 3.5 ppm.
Peak to peak frequency response
0.15 dB.
Peak to peak group delay response
10 ns.
Phase noise
≤ -104 dBc/Hz @ 20kHz offset.
Conducted spurious and harmonics
< -60 dBc, FCC 47 Part 74.
Radiated spourious and harmonics
< -80 dBc, FCC 47 Part 74.
MER (Modulation Error Rate)
≥ 29 dB (transmitter output) typical.
RF output connector
N
Communication
Hyper-terminal
RS232 (DB-9)
External Command – ON/OFF
(DB-9)
Mechanical
Air speed over drawers
50 ft/minute.
Dimensions
5UR (H), 19”(W), 26”(D)
Weight
Gross: 110 lb.
AT7120 Owner Manual Rev. 1.1 – March 2009 15/76
Section 2 – Control Set
Functional Description
The digital control is responsible for all management of AT7120 transmitter.
This unit Monitors and assures the system is operating within acceptable parameters and provides user control
access via key pad located on the front panel, or via RS232 hyper-terminal.
Its main attributions are:
Warns of signal lock failure of the PLL in the up-converter.
Warns of excessive temperature of the 60W amplifier.
Monitors and displays the RF direct and reflected powers of the 60W amplifier, muting the
transmission in case of extreme levels.
Displays DC current levels of the main power supply module (I1).
Process and displays power supply voltage(s).
Sets in the operational channel of the Up-converter unit and transmits power levels via ALC.
Sets and monitors the operational channel frequency in the up-converter unit as well as the
transmit power levels which is controlled by the automatic level control circuits.
The control unit is directly connected to a keypad and LCD screen, both located on the front panel of the
transmitter AT7120. Numerous parameters can be set via the keypad and monitored by the LCD screen.
The same functions can be performed via RS232 HyperTerminal connection.
Control unit block diagram
CONTROL
UNIT
CIP8231
(CIM3297)
MICROCONTROLLER
DISPLAY
CIM3004
KEYBOARD
CIP8002
(CIM3003)
EXCITER FORWARD POWER READING
EXCITER REFLECTED POWER READING
EXC.20W ID CURRENT READING
VOLTAGES SUPPLY READINGS
RS232 REMOTE CONTROL
EXTERNAL FUNCTIONS
Fig.2.1: Control unit general block diagram
AT7120 Owner Manual Rev. 1.1 – March 2009 16/76
The printed circuit board CIP8231 is referred to as the control unit, and provides the major functionality
of the AT7120 digital control unit.
For a better understanding of the functioning of this board please refer to Fig.2.1 “Control unity general
block diagram”, above, which depicts the main components and connections. Figure 2.2, below, shows
a detailed schematic of CIP8231 including connector pin layout.
01 control unit board - CIP8231 (CIM3297)
01 keypad board - CIP8002 (CIM3003)
AT7120 Owner Manual Rev. 1.1 – March 2009 17/76
01 20 x 2 LCD display board - CIM3004
CIP8231 Connections
(BK) SW2 PIN 3 –CON 6 –CIP8388 –MOD. 4492 –UHF UPCONVERTER
(GR) TEMPERATURE ALARM PIN 4 –CON-5 –CIP8209 –MOD.4408 –UHF AMPLIFIER
(GY) RESTART PIN 6 –CON-8 –CIP8111 –MOD. 4401 –POWER SUPPLY
CON-1
BL
7
CON-2
1 9
9
1
3
6CON-7 CON-8 CON-9
1
GND
VCC
DA1
DA2
+15V
IRQ
CON-3
1
6
CON-4
8
CON-5
8
1
CON-6
8
1
PA21
PA31
PA41
PA51
PA61
PA71
1
PA02
PA12
PA22
PA32
PA42
PA52
PA62
PA72
PB01
PB11
PB21
PB31
PB41
PB51
PB61
PB71
PB72
PB62
PB52
PB42
PB32
PB22
PB12
PB02
GND
TX
RX
PC6
PC5
GND
A16
A15
A14
A13
A12
A11
A10
A09
GND
A08
A07
A06
A05
A04
A03
A02
A01
CI -7
LM7805
CI-1
1 2 3
TPO-1
AJUSTE
LUM. DISPLAY
XTAL1
1
14
SCL
SDA
PM4
PM3
PJ1
PJ0
16MHz DTR
CTS
RX
TX
GND
RTS
DCD
CON-11
1
6
CON-10
1
7
J1 VM
BDM IN
MC34064
LM358
CI -4
MCS12A128BMCS12A128B
MC9S12A128B
Q1
BCX53
CON-12
1
1
.
DS229
..
RS232
RS485
J4
J5
.
DS229
CI -6
CI-2
.
CI-3
.
(GY) DATA PLL PIN 6 –CON-3 –CIP8388 –MOD. 4492 –UHF UPCONVERTER
A
B
GND
(WH) RX RS232 PIN 2 –CON DB9 RS232 –REAR PANEL
(RD) TX RS232 PIN 3 –CON DB9 RS232 –REAR PANEL
(SH) GND RS232 PIN 5 –CON DB9 RS232 –REAR PANEL
(WH) GND PIN 1 –CON-6 –CIP8388 –MOD. 4492 –UHF UPCONVERTER
(BL) +15V PIN 1 –CON-13 –CIP8111 –MOD. 4401 –POWER SUPPLY
(GR) +8V PIN 1 –CON-11 –CIP8111 –MOD. 4401 –POWER SUPPLY
(YL) ENABLE QDAC PIN 8 –CON 6 –CIP8388 –MOD.4492 –UHF UPCONVERTER
(GY) SW1 PIN 4 –CON 6 –CIP8388 –MOD.4492 –UHF UPCONVERTER
(OR) CLOCK DAC PIN 7 –CON-6 –CIP8388 –MOD.4492 –UHF UPCONVERTER
(OR) LD CLOCK GENERATOR PIN 1 –CON-7 –CIP8358 –MOD. 4549 –8VSB MODULATOR
(BK) DATA OUT PIN 3 –CON-2 –CIP8357 –MOD. 4549 –8VSB MODULATOR
(BR) ENABLE PLL PIN 5 –CON-3 –CIP8388 –MOD. 4492 –UHF UPCONVERTER
(YL) CLOCK PLL PIN 7 –CON-3 –CIP8388 –MOD. 4492 –UHF UPCONVERTER
(VL) LOCK DETECT PIN 8 –CON-3 –CIP8388 –MOD. 4492 –UHF UPCONVERTER
(OR) DATA IN PIN 2 –CON-2 –CIP8357 –MOD.4549 –8VSB MODULATOR
(RD) MODULATOR CLOCK PIN 4 –CON-2 –CIP8357 –MOD.4549 –8VSB MODULATOR
(GR) MODULATOR ENABLE PIN 5 –CON-2 –CIP8357 –MOD.4549 –8VSB MODULATOR
(VL) MODULATOR READ PIN 6 –CON-2 –CIP8357 –MOD.4549 –8VSB MODULATOR
(VL) DATA DAC PIN 6 –CON-6 –CIP8388 –MOD.4492 –UHF UPCONVERTER
(YL) TX ON PIN 3 –CON DB9 –REAR PANEL
(RD) ENABLE IDAC PIN 9 –CON 6 –CIP8388 –MOD. 4492 –UHF UPCONVERTER
(YL) BACK LIGHT DISPLAY POINT A –LCD DISPLAY–CIM3004
(YL) CS MEMORY PIN 4 –CON-2 –CIP8437 –MEMORY INTERFACE
(YL) ROW1_KEYBOARD PIN 1 –CON-3 –CIP8002 –KEYBOARD
(BL) LINE1_KEYBOARD PIN 6 –CON-3 –CIP8002 –KEYBOARD
(GY) ROW3_KEYBOARD PIN 3 –CON-3 –CIP8002 –KEYBOARD
(OR) DCLK_MEM PIN 6 –CON-2 –CIP8437 –MEMORY INTERFACE
(OR) LINE3_KEYBOARD PIN 4 –CON-3 –CIP8002 –KEYBOARD
(WH / RD) ALC PIN 2 –CON-6 –CIP8388 –MOD. 4492 –UHF UPCONVERTER
(RD) ASDI_MEM PIN 5 –CON-2 –CIP8437 –MEMORY INTERFACE
(VL) DATA_MEM PIN 3 –CON -2–CIP8437 –MEMORY INTERFACE
(RD) +32V OUTPUT VOLTAGE READING PIN 5 –CON-8 –CIP8111 –MOD. 4401 –POWER SUPPLY
(OR) +32V OUTPUT CURRENT READING PIN 1 –CON-7 –CIP8111 –MOD. 4401 –POWER SUPPLY
(BL) +15V READING PIN 2 –CON-8 –CIP8111 –MOD. 4401 –POWER SUPPLY
(BR) TEMPERATURE READING PIN 5 –CON-6 –CIP8388 –MOD. 4492 –UHF UPCONVERTER
(BL) FORWARD POWER READING PIN 1 –CON-5 –MOD. 4408 –UHF AMPLIFIER
(WH) GND INPUT EXTERNAL PIN 5 –CON-DB09 –PANEL
(GY) REFLECTED POWER READING PIN 2 –CON-5 –MOD. 4408 –UHF AMPLIFIER
(GR) +8V READING PIN 1 –CON-8 –CIP8111 –MOD. 4401 –POWER SUPPLY
(BK) -15V READING PIN 3 –CON-8 –CIP8111 –MOD. 4401 –POWER SUPPLY
(BK) LINE2_KEYBOARD PIN 5 –CON-3 –CIP8002 –KEYBOARD
(BR) ROW2_KEYBOARD PIN 2 –CON-3 –CIP8002 –KEYBOARD
Fig.2.2: CIP8231- the control unit board - components and connections.
The major components and functions of CIP8231 are described below:
Integrated circuit CI-4 (A128) is a 16 bit microcontroller programmed in assembly that performs all
system management functions. This component is programmed in the factory and includes a numeral
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designation identifying the unity and software version. The unit contains firmware control software that
allows the operating system software to be updated as needed.
All the available analog parameter information from the system is sent to connector CON-9 on the
CIP8231 board. The parameters monitored and displayed are as follows:
Direct power – 120W Amplifier
Reverse power - 120W Amplifier
(+9V) - Power supply
(+18V) - Power supply
(-18V) - Power supply.
(+32V) - Power supply.
(I1) – the main power supply electrical current.
The analog signals are sent to microcontroller CI-4, where they are digitalized and processed. The
software of this microcontroller compares the readings with the stored nominal values. Readings
outside of nominal values generate associated alarms. Values and alarm states are displayed on the LCD
panel located on the front of the unit. Important note: The equipment is designed so that a nominal
analog reading presents +4 volts DC to the Con-9 connector. The voltage level presented to Con-9 can
be adjusted during setup or maintenance when external equipment is used to assure proper calibration /
reading.
Each module that generates analog control / monitoring information has an associated test point on the
unit. If during the calibration process external measurements indicate the correct nominal value for that
function, a trimpot is adjusted to set the voltage on the test point to +4Volts.
Note: Set the voltage on the test point associated with reflected power, if the voltage becomes higher
than +4Volts, the control unit will process this event as an alarm. This event is associated with a reverse
power in excess of 10% of the transmit power.
Alarm detection
For the alarms listed below, the CIP8231 control unit board shuts down the transmission by Setting the
Automatic Level Control (ALC) to zero volts (provided to the up-converter module 4492). For more
details see the power control description on the next page.
The following alarms reach the connectors CON-4, CON-5 and CON-6 at the CIP8231 board as digital
information.
In case of substitution of the CI-4 or the entire PCB CIP8231, it is mandatory to
provide the factory, prior to replacement, the programming identification number
that is clearly indicated on CI-4.
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Lack of lock voltage of the PLL at the Up-converter - Module 4492.
Excessive temperature of the 60W UHF amplifier - Module 4407 – (above 65ºC).
Excessive reverse power (above +4V at CON-9).
Overflow of the FIFO register in the 8VSB modulator (communication between microcontroller
and modulator).
Failure of synchronization of the transport data (MPEG) stream
Presence of non-programmed hardware (a false alarm may present during the warm-up phase of
the equipment).
Imperfections associated with the generation of master clock signal in the modulator 8VSB -
Module 4549.
Nominal operation of the equipment presents +5Vdc on the alarm pins on CON-4 and CON-6; CON-5
indicates that there is no alarm condition. An alarm state is indicated by a voltage of less than 5 VDC.
In most cases the alarm state will present zero volts dc to the associated connector. The microcontroller
(CI-4) will inhibit transmission during an alarm state.
The alarms generated in the system are shown in the LCD display of the MCU. The corresponding
indication for these alarms are “*” for active alarms - - and “#” for previous alarms (an alarm state that
has been resolved or that has ended.) - PAST. The occurrence of an alarm “*” will automatically end the
transmission. When the reason for this alarm “*” is resolved, a symbol “#” will appear and the
transmission will be restored automatically. To erase old alarms, just press the “CLR.ALL” key on the
front panel of the equipment or when using a hyper-terminal press “1” on the keyboard.
Communication with 8VSB modulator
The CIP8231 board communicates with the 8VSB modulator - Module 4549 - through a set of serial
port interfaces (SPI). These SPI’s are located on pins 2 to 5 of connector CON-3 and on pins 5 and 6 of
connector CON-5.
The communication between CIP8231 board and the 8VSB modulator - Module 4549 - monitors and
sets the configuration parameters of this module. For example, the adjustment of the pilot programming
stream (the 8VSB signal), and adjustment of the superior lateral band rejection are managed over this
communication interface.
Setting the FCC/UHF operational channel
The operational channel of the equipment is set via the CIP8231 board. The board generates a code that
represents the selected channel (UHF) which is then sent over the SPI to the up-converter - Module 4492
- This stream of information is composed by data, clock and enabling code, and is presented on pins 1, 2
and 3 of connector CON-4 of the CIP8231 board.
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The control board also sends the operational channel information to program the PLL circuit at
CIP8388, which will then synthesize the local oscillator frequency required to create the desired
channel. During normal operation the CIP8231 continuously manages the PLL of module 4492.
It is important to remember that the initial programming of the CIP8231 board for the transmitter
AT7120 is made at the factory. These programming procedures are not accessible to the end user.
In turn, Module 4492 sends the lock detected information to the CIP8231 board indicating that the PLL
circuitry is in lock and ready for operation. This information is presented as voltage level of
approximately +3.6V and is routed to pin 5 of connector CON-4. The absence of this voltage will trigger
the lock alarm that will terminate transmission (RF output power is set to zero dbm) and present an
alarm “*” on the LCD display located on the front panel of the transmitter.
RF power control
RF transmitter power is set by the end user, via the front panel. The CIP8231 board converts this digital
input programming information into analog voltage levels. This voltage is then sent to the up-converter
of the exciter. This specific voltage level is called ALC REFERENCE VOLTAGE or trellis voltage, and
is shown on the LCD digital display as V.P. Adj.
The trellis voltage is directly proportional to the RF power level at the output of the exciter, in other
words, the higher the trellis voltage the higher the exciter RF power level. The typical value of trellis
voltage at normal rated power output is between 3V and 4V.
In case of failures or malfunctions, the power control is responsible for acting immediately to set the RF
power level to zero, thus correspondingly, the trellis voltage is set to zero. This may occur in during any
alarm state where transmission must be terminated to protect equipment or to maintain regulatory
compliance.
A warm up period of approximately five (5) seconds is required for the exciter to reach nominal RF
power. This period of time, is also known as SLOPE UP time, it is the time necessary for the trellis
voltage to increase from its initial zero volts up to its the value, set corresponding to the programmed RF
power level as measured at the output of the transmitter.
Programming the off-set operational frequency
The AT7120 transmitter is factory set to a FCC/UHF operational channel, under ATSC standards. The
channel off-set frequency can be changed at the end user discretion. The offset can shift the RF channel
band up to 30 kHz, in 1Hz increments. The shift of frequency can increase or decrease the start
frequency of the band of the UHF channel. The offset is programmed at the CIP8231 board, which
provides control signals to the up-converter - Module 4492 - on pins 1, 2, 3 of connector CON-4.
While the equipment is turned on, the CIP8231 board automatically re-confirms the last set of
programmed data at the up-converter – module 4492. The programming instructions generated by the
CIP8231 board of the transmitter are set at the factory and, therefore, are not accessible to the user.
+32V power supply ON/OFF control.
The CIP8231 board sends a +5 volt dc signal to the power supply - Module 4401- to switch it ON. The
signal is located at pin 6 of connector CON-3.
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In the absence of this signal, the power supply - Module 4401 - will stop supplying the +32 volt line,
which feeds the 60W UHF amplifier - Module 4407. The other voltages remain present if the transmitter
is operational.
Serial communication RS232
The access to CIP8231 board is through a PC that has the Windows Hyper Terminal. At the rear panel of
the transmitter there is a DB9 connector - tag as RS232- which is linked to connector CON-10, located
at CIP8231 board.
Keypad – CIP8002 board
The CIP8002 board contains five key buttons SW1 to SW5, located on the front panel of the transmitter.
This board is a matrix of electrical ON/OFF contacts. The responses are made available at the connector
CON-3.
LCD - CIM3004 board
CIM3004 board is a LCD - Liquid Crystal Display - of 20 columns by 2 lines. The back light of this
display is controlled by the CIP8231 board which sends +5V between a test point termed A+ (yellow
wire) and ground test point termed K- (white wire). The trimpot TPO-1 located at CIP8231 board
controls the intensity of the characters of the display. The jumper J1, also located at CIP8231 board, can
be set to the R61 position, if the LCD back light is desired to stay ON at all time.
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Section 3 – 8VSB Modulator and Master
Clock
Module 4549
Introduction
The Module 4549 is composed by an 8VSB MODULATOR including an IF pre-correction circuit board
(CIM3510) and the MASTER CLOCK UNIT, CIP8358.
Each one of these printed circuit boards are located below one of the two lateral covers of module 4549,
as it shows the drawing of external connections of this module.
(a)
(b)
Fig.3.1: Module 4549, (a) top view, (b) connectors, from rear panel
Internal 10MHz TCXO ref. input
10MHz OCXO ref. output to Up Converter
172MHz Master Clock
8VSB IF Modulated - 18.8339 MHz
IF (I) carrier
IF (Q) carrier
8VSB Modulator
Section
Master Clock
Section
Transport Stream Input
10MHz External Reference Input
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General Functional Description
Module 4549 consists of 2 printed circuit boards. This section describes the 8VSB modulator only; the
Master Clock is described in the next section. The two boards are physically located below each side of
the top covers, as shown on the figure above.
CIP8412 board - 8VSB Modulator/Pre-corrector
The CIP8412 is part of the Module 4549. The 8VSB modulator process the transport stream (TS) that
carries up to 4 broadcast programming signals including, audio, video and data. All the information is
compressed and multiplexed in a MPEG2 format.
Fig.3.2: CIP8412 – 8VSB Modulator Block Diagram
The 8VSB channel modulator inserts the forward error correction, (FEC), into the MPEG2 transport
stream. The modulator follows the ATSC standard A/53 annex D.
CIP8412 board - functional description
The input TS signal to be modulated must be in either ASI or SMPTE310M format, 19.39Mbps bit rate,
and 800mVpp @ 75 ohms. The ASI/SMPTE 310M input is located on the rear panel by a BNC
connector.
First the circuit responsible for the clock rate is used to perform the protocol interface. After that, there
is a rate equalization of the TS performed by the insertion or removal of null packets. At the end, the
symbol rate is ready to be stabilized and locked with an external/local reference of 10MHz rather than
with the TS that is limited to 2.8ppm accuracy. This processing also includes PCR (Principle Response
Curve) re-sampling for multiple programs,.
The entire 8VSB modulation process is digital. This process includes the FIR filters, not analog SAW
filters, to create the VSB band. Digital modulation increase the quality of the modulated signal as
measured via a proportional improvement of the MER, (Modulation Error Rate). The modulation
process generates two identical but orthogonal signals, I and Q. The frequency of the IF carrier is
21.52MHz, and the center of the channel is 18.8MHz.
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The benefit of working with two orthogonal carriers is: the possibility to implement corrections on non-
linear distortions, or simply implement digital pre-distortion. The digital pre-correction is possible using
LUT (Look up Tables); refer to Section 9 for more details. This table synthesizes inverted responses
regarding the RF power amplifier transfer function, reducing the IMD products.
The digital processing generates I and Q distorted, and these two signals are then converted analog via a
16 bits DAC, with two balanced outputs, with a total of four output analog signals. These signals are
termed; I, I’, Q and Q’, and are respectively present at the CN9, CN8, CN6, and CN5 connectors on
CIM3444.
These four signals will become the UHF up-converter - Module 4453 - input signals. After the data
stream is processed to receive the channel coding. This process contains the following steps:
Frame synchronization
For each 188 bytes on the MPEG2 package, this circuit identifies and removes the 47th byte.
Randomizer
This circuit equally spreads the modulated signal’s energy over the channel band. The final energy
density is similar to an Additive White Gaussian Noise. ; This technique greatly improves bandwidth
usage efficiency.
Reed-Solomon
Reed-Solomon is a block coder (207,187) that adds 20 redundant bytes on each 187 bytes of the MPEG2
package. With this method it is possible to detect and correct data errors that occur during the
transmission process.
Interleaving
Data stream interleaving is utilized to lower the transmissions susceptibility to interference that causes “burst data
errors.”
Trellis Code
Trellis code is closely related to the channel modulation. It is a convolution coder utilizing 2/3 rate, i.e.
for each 2 bits at the input, there are 3 coded bits at the output, creating the 8 symbols used on the 8VSB
modulation process (-7, -5, -3, -1, +1, +3, +5, +7). The encoding effectively improves the ability of the
data stream to withstand degradation during transmission effectively increasing the signal-to-noise ratio.
Synchronism Insertion
The synchronism insertion builds the data stream’s overall structure, creating the fields and frames as
specified on the A/53E standard.
Pilot Insertion
The low-level pilot is created by adding a DC (+1.25) value to the baseband data (data and Sync) . After
modulation, the DC value causes an in-phase pilot to be added to the data spectrum for transmission. The low-
level pilot is a constant RF level below the average data signal power and has a frequency offset from lower band
edge. The low-level pilot aids carrier recovery and is independent of the data.
Master Clock – CIP 8358 board – (CIM 3445)
Introduction
The CIP8358 board embedded into the module 4549, uses a 10MHz internal/external reference signal, to
synthesize a 172.16MHz signal that is 16 times the symbol rate used in the modulation process.
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This oscillator signal is squared by a Schmitt-trigger circuit with amplitude equal to 0-3.3 volts. This
square wave provides the master clock signal that synchronizes all the digital circuits of this system,
except the control signals.
Fig.3.3: CIP8358 master clock – block diagram
CIP8358 board – general functional description:
The 172.16MHz frequency is synthesized via a PLL, a VCO and a DDS circuit. There are two possible
10MHz signals but the external reference takes priority over the internal. The first signal comes to
CIP8358 via a SMB connector, CON-1. The second signal is also 10MHz, generated by the DDS (Direct
Digital Synthesizer) circuit out of the free running 172.16MHz oscillator.
The loop filter performs the integration of the phase comparator output, generating the error signal that
is feed back to the VCO. This way, the VCO is locked to the external reference signal.
The oscillator signal is delivered via 3 connectors located on the CIP8358 board. Two of those signals
are routed to the 8VSB Modulator - CIM3510 board.
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Section 4 – IF/UHF up-converter
Module 4492
Introduction
The module 4492 performs the following basic functions:
This module translates the incoming I and Q IF carriers from the 8VSB modulator, to the desired
FCC/UHF channel.
Controls the RF output power of the exciter.
The desired channel is entered via the keypad and the LCD display in the factory. Channel changes are
not allowed by the end user.
Fig.4.1: Module 4492, RF connections.
The main features associated with this module are:
Simple conversion
Orthogonal mixing, which performs the image and LO rejections
Synthesized local oscillator via PLL, 22 bits serial fractional
Allows channel offset programming @ 1Hz resolution when using external 10MHz? reference
RF Output
Ref. 10MHz input
2 x LO sample
(Q) IF input
(I) IF input
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The LO frequency is divided by two, to reduce the phase noise level by 6dB
10MHz internal reference oscillator, technology OCXO, (Oven Controlled Crystal Oscillator)
Uses hybrid amplifiers with high linearity
Overdrive protection circuit, maintains the RF output power at acceptable levels
Automatically reduces the exciter RF output power in absence of IF signal, either Q or I carriers
Stand-by for local oscillator, in case of a failure in the external reference signal
Meets or exceeds the phase noise requirements for DTV transmission
Module 4492 - General functional description - Refer to Fig.4.2.
Fig.4.2: Module 4492 – block diagram
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The already modulated IF carrier I and Q feed the 2 inputs of the up-converter – Module 4492. The
output signal of this module is a FCC/6MHz/UHF channel (14-69). Besides this main function, it also
controls the potential overdrive into the final 60W amplifier.
The up-conversion circuit consists of an orthogonal mixer fed by the IF carriers, I and Q respectively
with a fixed center frequency and 6 MHz bandwidth. The mixer converts the IF signal using the local
oscillator CW (Carrier Wave) signal. This mixing results in two RF lateral bands. The superior lateral
band is not desirable and is attenuated by 35dB.
The resultant RF signal is filtered and amplified. The serial data stream that program the PLL circuit is
transferred via MICROWIRE interface, composed by 3 high speed transfer lines of 20MHz. The
microcontrollers inside the up-converter perform the following functions: {needs clarification}
PCB CIM3443 – Local Oscillator
The local oscillator is designed based on a PLL circuit. This oscillator is able to synthesize frequencies
within the band from 450MHz up to 900MHz. To guarantee a high quality local oscillator signal, 4
VCO’s (voltage controlled oscillator) are implemented with a shift frequency range of 125MHz each.
Just one VCO works at the time to avoid interference. This approach achieves a 102dBc@20Hz phase
noise level. The synthesizer on the feedback loop selects the desired frequency inside the chosen VCO
band.
The VCO’s signal outputs are isolated via sum and inverted circuits. The reference frequency generated
by a DDS circuitry completes the up-conversion frequency process. The output local oscillator signal
power is +5dBm.
PCB CIM3443 – Local Oscillator – block diagram
Fig.4.3: CIM3443 local oscillator – block diagram
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PCB CIM3442 – UHF Mixer
The mixing operation translates the IF modulated signal frequency up to the assigned UHF broadcasting
channel, the operation utilizes the orthogonal pair of signals (I-, I+) and (Q-,Q+) allowing rejection of
one side band, and the oscillator itself. The rejection is around 40dB, facilitating the post filtering steps.
Right after the mixing operation, the RF broadband signal is (VHF and UHF) amplified 10dB under a
typical 2dB roll-off characteristic. The RF output pass through a 25dB dynamic range variable
attenuator. The control of this attenuator is related with the DC level generated by the ALC (Automatic
Level Control). In case of absence of an IF signal, a valid IF signal (locked via PLL) or any of the 4
possible IF signals; the attenuator assumes its highest level of attenuation, and shuts down the RF
amplification chain.
PCB CIM3442 – UHF Mixer – block diagram
Fig.4.4: CIM3442 UHF mixer – block diagram
PCB CIM3442 – UHF Mixer – adjustment procedures:
The mixer-ALC has two types of adjustments. The first one is a DC level that polarizes each branch of
the input of the complex mixer. Each one of the DC levels must be adjusted to assure maximum
rejection of the undesired vestigial side band, in conjunction with the LO rejection as well. The level
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adjustments are performed by the trim pots: TPO-1, TPO-2, TPO-3, and TPO-4. Voltage range of +1.4V
to +1.6V should be present on the following test points.
TPO-1: readings on L17
TPO-2: readings on L18
TPO-3: readings on L19
TPO-4: readings on L20
Once the first set of adjustments is completed, the fine tuning adjustment should be performed. It is necessary to
connect the spectrum analyzer to the UHF RF output of the sub-module 4453. At this point, (Both the LO signals,
as the superior RF spectral image of the UHF/ATSC RF channel, must be attenuated by 40dBc to be compliant
with product specification.
40dBc
UHF / ATSC
CHANNEL DTV
(BELOW MIXING)
LOCAL OSCILATOR
SIGNAL
UHF / ATSC
CHANNEL DTV
(ABOVE MIXING)
40dBc
UHF / ATSC
CHANNEL DTV
(BELOW MIXING)
LOCAL OSCILATOR
SIGNAL
UHF / ATSC
CHANNEL DTV
(ABOVE MIXING)
Fig.4.4: Level references for mixer-ALC fine tuning
The second adjust detects the protection signal at the center of the band. If 1 out of 4 controls signals are
absent, the DC monitoring voltage level exceeds the min threshold and shuts down the RF output signal.
The DC threshold adjust is performed by TPO-5, and should be set for +2.5V.
Module 4466 – Direct Digital Synthesizer (DDS)
Module 4466 is a signal reference generator based on a DDS circuit. This module is able to synthesize
frequencies up to 50MHz under mHz precision range. The signal is used as PLL reference on the UHF
up-converter, Module 4453 – PCB CIM3442. If necessary, the 10 kHz RF channel off-set is pre-set on
the DDS circuitry. The phase noise of the reference signal generated on this module is better than
110dBc/Hz.
The SCU unit – PCB CIM3297 – configures the DDS’s circuitry parameters via a serial communication
port. The DDS module receives a signal out from the master clock, Module 4454 - PCB CIM3445 and
performs the programming operation for the RF output channel as required under mHz precision. A
frequency error around 1Hz maximum is achieved as measured at the output of the UHF mixer circuit.
Before the DDS signal leaves the module, it is amplified and filtered.
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Section 5 – UHF ATSC Exciter
Module 4407
General Functional Description
Module 4407 has high linearity solid performance for TV signals across the entire UHF band. This
module was developed to operate in two UHF bands including:
• LOW BAND (LB): channels 14 to 44
• HIGH BAND (MB): channels 45 to 53
A single PCB is used for the two bands of UHF listed above. The components of the PCB determine
which UHF bands in which the Module 4407 operates.
UHF / ATSC /8VSB AMPLIFIER - MODULE 4407
CIRCUIT
CIM
CIP
DRIVER
3391
8208
Module 4407 is divided in the following parts:
First Stage - Class A
This section uses the bipolar transistor T1 (SGA 9289). This transistor’s polarization is class A, which
insures highly linear amplification.
The transistor T1 is connected to the +18V main power supply, Module 4401. This voltage is available
at the pin-1 of connector CON-2 – Module 4407, where voltage regulator CI-1 reduce voltage to +5V;
this is the input voltage on T1.
The trimpot TPO-1 adjusts the collector current (IC) of T1. This adjust is made by measuring the loss of
voltage in resistor R8 (1Ω/1W), as the voltage is adjusted to 300mV, which corresponds to 300mA in
the IC.
Note:
Because this is Class A stage, the measurement of T1’s drain current must be the same with or without
input RF signal in the module.
T1’s gain is adjusted by the trimmer C12 and it is optimized for the highest value possible.
Second Stage – Class A
The transistor LDMOS T2 (MRF9030) is the main device of the second amplifier on Module 4407. This
transistor is also configured as a Class A amplifier.
The drain voltage is obtained from the +28V main power supply – Module 4401. This voltage is
available at pins 2, 3, 4 and 5 of connector CON-2 of Module 4407.
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The trimpot TPO-2 adjusts VGS of T2 and, consequently, the drain bias current (ID) of this transistor.
This adjust is made by measuring the loss of voltage in resistor R18 (2 x 10Ω/5W in parallel), as the
voltage is adjusted to 1V, which corresponds to 1A in the ID.
Note:
Because this is Class A stage, the measurement of T2’s drain current must be the same with or without
input RF signal in the module.
Trimmer C32 adjust the gain associate with T2 and is optimized for the highest value possible.
Third Stage – Class AB
This final amplifier device is the LDMOS transistor T3 (MRF373). This amplifier stage is configured as
a Class AB to assure superior efficiency without sacrificing linear performance.
The drain voltage in transistor T3 is obtained from the +28V main power supply – Module 4401. This
voltage is available at the pins 1, 2, 3, 4, 5 and 6 out of the CON-3 connector found in Module 4407.
The trimpot TPO-3 simultaneously adjusts the VGS for transistor T3 and, consequently, the drain bias
current (ID) of this transistor. This adjust is made by measuring the loss of voltage in resistor R40
(0.12Ω/5W), as the voltage is adjusted to 50mV, which corresponds to 416mA in the ID (in standby).
Note:
Because this is Class AB stage, the measurement of T3’s drain current increases as the input RF level
increases in the module. The correct measurements are obtained when the module is in standby, in other
words, there is no input RF signal in the module.
VGS Polarization Circuit for T2 and T3
Integrated circuit CI-5 is responsible for providing VGS to transistors T2 and T3. This circuit is powered
by the voltage regulator CI-3, which is powered by the +18V main power supply, Module 4401. This
voltage is present at pin-4 of the connector CON-5, Module 4407.
Temperature alarm
Module 4407 is protected against overheating. If the temperature rises above 65˚C, the protection circuit
acts and disconnects the module.
The protection circuit is composed basically of the thermal sensor S1 and the CI-2. The temperature of
the module converted into a DC voltage can be measured at pin-3 of connector CON-5. This voltage is
routed to pin-7 of connector CON-6 at CIP8231 - control unit. The lack of this voltage means that the
temperature of Module 4407 exceeded the 65˚ C. Under this circumstance, the control unit CIP8231 will
no longer allow the +28V power supply to feed the module.
RF Power Measurements
Through a PCB type directional coupler at CIP8208 board, a RF output sampling is collected in Module
4407. This RF sampling is sent to the direct and reversed power reading circuits.
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The detector circuit for direct power is basically composed by diode D2B, the operational amplifier CI-
4B and the trimpot TPO-4 that fine adjusts the detected DC level. The detected voltage will be displayed
at pin 5 of the connector CON-9 at CIP8231 board.
The reverse RF power reading is performed by diode D2A, the operational CI-4A and for trimpot TPO-
5, which adjusts the level of reading measured at pin 2 of connector CON-5.
Even though the reverse RF power reading is present at CIP8208, this reading is not planned for the
AT7120 transmitter.
Technical specifications
PARAMETERS
SPECS
INPUT
FREQUENCY
470 to 860MHz
MAXIMUM LEVEL
0dBm
IMPEDANCE
50Ω
CONNECTOR
SMB MALE
RETURN LOSS
≥ 13dB
RF OUTPUT
GAIN
43dB to 49dB
ATSC RMS POWER
Until 10Wms
HARMONICS 2nd
≤ -30dBc
IMPEDANCE
50Ω
GENERAL
VOLTAGE SUPPLY
26V to 30V
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Block Diagram
+5V REGULATOR
CI-1
+12V REGULATOR
CI-3
VGS REGULATOR
BIAS T2 AND T3
CI-5
TPO-3
VGS Adjust of T3
TPO-3
VGS Adjust ofT2
TPO-1
VGS Adjust ofT1
T1 T2 T3
RF DETECTOR
D2
DC AMPLIFIER
CI-4B
DC AMPLIFIER
CI-4A
TPO-4
Reading Adjust of Direct Power
TPO-5
Reading Adjust of Ref. Power
DIRECTIONAL COUPLER RF OUTPUT
+40dBm
RF INPUT
-5 a +3dBm
+28V
+28V
+15V
DIRECT POWER
READING REFLECT ED POWER
READING
+12V
+15V +12V
+12V
DC AMPLIFIER
COMPARATOR
CI-2
TEMPERATURE
ALARM
THERMAL SENSOR
S1
+12V
SGA9289 MRF9030 MRF373
+5V REGULATOR
CI-1
+5V REGULATOR
CI-1
+12V REGULATOR
CI-3
+12V REGULATOR
CI-3
VGS REGULATOR
BIAS T2 AND T3
CI-5
VGS REGULATOR
BIAS T2 AND T3
CI-5
TPO-3
VGS Adjust of T3
TPO-3
VGS Adjust ofT2
TPO-1
VGS Adjust ofT1
T1 T2 T3
RF DETECTOR
D2
RF DETECTOR
D2
DC AMPLIFIER
CI-4B
DC AMPLIFIER
CI-4B
DC AMPLIFIER
CI-4A
DC AMPLIFIER
CI-4A
TPO-4
Reading Adjust of Direct Power
TPO-5
Reading Adjust of Ref. Power
DIRECTIONAL COUPLER RF OUTPUT
+40dBm
RF INPUT
-5 a +3dBm
+28V+28V
+28V
+15V
DIRECT POWER
READING REFLECT ED POWER
READING
+12V
+15V +12V+12V
+12V
DC AMPLIFIER
COMPARATOR
CI-2
DC AMPLIFIER
COMPARATOR
CI-2
TEMPERATURE
ALARM
THERMAL SENSOR
S1
THERMAL SENSOR
S1
+12V
SGA9289 MRF9030 MRF373
AT7120 Owner Manual Rev. 1.1 – March 2009 35/76
Section 6 – UHF ATSC Amplifier
Module 4442
General Functional Description
AT7120 transmitter has two Modules 4442 connected in parallel, which work as digital TV end
amplifiers in all UHF band.
Module 4442 offers high linear precision that works satisfactorily with digital TV signals. However, to
achieve optimal gain, this module was divided in 3 operational channel bands, which are:
Channels 14 to 25
Channels 26 to 38
Channels 39 to 53
For the four UHF channel bands described above, the same circuit board is used.
UHF/ATSC amplifier module 4442
CIRCUIT
CIM
CIP
DRIVER
3431
8431
What defines which UHF band of Module 4442 is used are certain components that might or not be
excluded or alter the value.
Module 4442 is made of two Push-Pull amplifiers cells, class AB. Each cell has a double Push-Pull
transistor, with LDMOS technology. This module can offer up to 70W.
To better understand how the amplifier works, refer to the block diagram in the upcoming pages.
The amplifier is made of the following components:
Input Coupler
The input RF coupler equally divides the UHF signal present in the input connector for the two
amplification cells, maintaining 50Ω impedance.
The 3dB 90˚ hybrid coupler SMD built by “sandwiching” together two small boards called stripline.
This hybrid coupler has 4 gates (terminals); in one of this gates is applied an input signal, which will be
divided internally; the two resulting signals are applied in the direct and adjacent gates. There is also an
isolated gate, where a 50Ω balance charge is placed. This charge is delivered by the resistor, R1.
This charge basically guarantees a constant impedance of 50Ω, even if one of the cells comes to fail. By
coupling, the other line receives the input signal and transfers it electronically to the two amplification
cells.
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Cell A – 35W Amplifier
The amplification cell A is obtained by a Push-Pull 35W amplifier, class AB. Transistor T1 is in this
cell. The polarization circuit of cell A is made of a VGS timer circuit with temperature compensation,
differential amplifier and gate impedance reducer. TPO-1 trimmer adjusts the VGS to the T1 transistor.
Adjusting the VGS1, also adjusts the quiescent current (automatic adjustment of the T1 transistor’s
current). This current is measured indirectly, by dividing the reduction in voltage measured between
resistors R34 and R35 (that are in parallel) and its resulting ohm value, that is 0.06Ω.
Trimmers C7, C10 and C13 adjust input paring up and this cell’s gain. The circuit RL made of resistors
R27 and inductor L8, plus resistor R26 and inductor L7 avoid transistor T1’s auto-oscillation in
frequencies below 200 MHz, for which it is not pared up. Resistors R25 and R28 together with transistor
T3 reduce gate impedance for DC. Capacitors C37, C14 and C15 work as DC non-couplers in transistor
T1’s gate.
Cell B – 35W Amplifier
Just as cell A, cell B’s amplification is obtained by a Push-Pull 35W amplifier, class AB. Transistor T2
is in this cell. The polarization circuit in cell B also is made of a VGS timer circuit with temperature
compensation, differential amplifier and gate impedance reducer. TPO-2 trimmer adjusts the VGS to the
T2 transistor. After adjusting the VGS2, an automatic adjustment of the T2 transistor’s current. This
current is measured indirectly, by dividing the reduction in voltage measured between resistors R36 and
R37 (that are in parallel) and its resulting ohm value, that is 0.06Ω.
Trimmers C23, C26 and C29 adjust input paring up and this cell’s gain. The circuit RL made of resistors
R30 and inductor L6, plus resistor R31 and inductor L5 avoid transistor T2’s auto-oscillation in
frequencies below 200 MHz, for which it is not pared up. Resistors R29 and R32 together with transistor
T4 reduce gate impedance for DC. Capacitors C38, C30 and C31 work as DC non-couplers in transistor
T2’s gate.
Output Coupler
It is a hybrid coupler built with a special semi-rigid coaxial cable, better known as “wireline”. This type
of cable has 2 internal conductors interlinked; this set has the characteristics of a hybrid coupler. As the
input coupler, this coupler also has four gates (input/output; isolated, -3dB 0˚, -3 dB 90˚).
The same concept used with the input coupler is used in the output coupler, what differs is that its
function now is to add amplified signals by the 35W cells. The unbalanced output charge is represented
by resistor R38 (50Ω/60W). This charge guarantees that the module’s output impedance is always 50Ω,
even if one of the cells comes to fail.
Temperature Alarm
Module 4442 has a protection circuit that disarms the module in case the temperature rises above 65˚ C.
This circuit is basically made of thermal sensor S1, DC amplifier and voltage comparator CI-1. The
module temperature is converted into voltage, DC, by the temperature sensor (10 Mv/˚C). This voltage
value is amplified and then compared with a reference voltage, thus getting an alarm voltage, which can
be measured on the green cable connected to the module. This voltage is sent to pin 2 of connector
CON-7 in the subordinate feeding power supply corresponding to the amplification module. In this
AT7120 Owner Manual Rev. 1.1 – March 2009 37/76
power supply the alarm voltage is interlinked to pin 4 of connector CON-4 and finally, sent to the
control unit. The loss of this voltage means that the temperature on Module 4442 exceeded 65˚C and in
this situation the control unit will order the subordinate power supply to send +28V to the correspondent
Module 4442.
Technical Specifications
CHARACTERISTIC
SPECIFICATION
INPUT
FREQUENCY
470 - 806MHz
LEVEL
+36 to 34dBm
IMPEDANCE
50 Ohms
CONNECTOR
N FEMALE
RETURN LOSS
≥ 25dB
OUTPUT
GAIN
Channels 14 to 25 = 15dB
Channels 26 to 69 = 14dB
ATSC AVERAGE POWER
70Wrms
HARMONICS 2RD
<-25dBc
SPURIUS EMISSION
<-40dBc
SHOULDER
36dB
IMPEDANCE
50 Ohms
CONNECTOR
N FEMALE
GENERAL
VOLTAGE SUPPLY
+32V
CONSUMPTION
9A
AT7120 Owner Manual Rev. 1.1 – March 2009 38/76
Board CIP8431 – Adjustment Procedure
The tests on Module 4442 can be done with the output points connected to the rest of the RF structure of
the equipment, or with the output connected to a coaxial charge 50Ω/100W (minimum) that has a good
response in UHF TV (470MHz to 860MHz). However, whatever is the use of Module 4442, it is
important to make the adjustments with the module RF output connected to a coaxial charge.
Never operate Module 4442 without making sure its output is properly charged. The absence of a
coaxial charge, or if it doesn’t meet specifications, might cause severe damage not just to the
transistors but also to the test equipment.
In case it is decided to adjust Module 4442 outside the transmitter, it will be necessary to use a +28V
power supply. The output current of this power supply should not be smaller than 2.5A, as long as the
tests that need to be done don’t require maximum power output from the module. To adjust currents and
the response curve, the +28V/2.5A power supply is sufficient.
ID Current Adjustments
To adjust ID drain currents of both transistors, T1 and T2, Module 4442 must be idle.
Never adjust ID drain currents of Module 4442 LDMOS transistors while there is an input signal in the
module. To adjust currents, make sure Module 4442 input signal is in standby, otherwise the transistor
might be damaged.
To perform a more accurate adjustment it is best to wait at least 5 minutes after module has been
powered up, to make sure there is a thermal stability in the module when in standby.
The measuring instrument to be used during testing procedures is a digital multimeter with scale in
mVdc. Avoid the use of multimeter with auto-range.
Transistors T1 and T2
1. Adjust trimpots TPO-1 and TPO-2 totally anti-clock wise, thus zeroing T1 and T2’s drain
currents.
2. To adjust T1’s quiescent current, insert the digital multimeter with a maximum scale of
100mVdc to measure loss of voltage in resistors R34 and R35 (drain resistors for T1).
3. Note: These two resistors are in parallel, thus the voltage can be measured on either of them (R34
or R35).
4. Slowly adjust trimpot TPO-1 clock wise until T1 is set; then some loss in voltage (few mV) will
be observed. Continue adjusting TPO-1 until its voltage measures 60mVdc, what translates to a
drain current of 900mA for the BLF861A transistor.
AT7120 Owner Manual Rev. 1.1 – March 2009 39/76
5. To adjust T2’s quiescent current, slowly adjust trimpot TPO-2 clock wise until T2 is set, when
then some loss in voltage, few mV, will be observed. Continue adjusting TPO-2 until its voltage
measures 60mVdc, what translates to a drain current of 900mA for the BLF861A transistor
Notes
The BLF861A transistor is type Gemini; this means there are two identical transistors inside the capsule.
That is why one trimpot was omitted when balancing the VGS voltage. Another characteristic of this
transistor is that the drains are connected internally, so when a 900mA current is measured, it really
means that each side of the transistor has a drain of 450mA.
Because this is a phase amplifier class AB, the measured drain current of the LDMOS transistors
increases as the RF level increases in the input of the module. The correct values are obtained with the
module in standby, in other words, without input RF signal.
In the case that these adjustments are not possible, measure the gate resistance with a multimeter (this
resistance got to be at least 330 ohms). If the gate resistance is close to 0 ohm, it is possible that the
transistor is broken.
Check for temperature alarm
Module 4442 has a thermal sensor (S1) that when connected to operational circuits (CI-1), generate
alarms that detect when the module temperature is above 65˚C.
1. Power Module 4442 with +28V and wait for the pre-heating to be done for around 5 minutes. It
is not necessary for Module 4442 to be in maximum power; actually it is better to do this adjust
with Module 4442 in standby, in other words, without input RF signal.
2. Measure voltage on pin-2 of thermal sensor S1.
3. Measure voltage on pin-2 of operational circuit CI-1; this voltage is exactly ten times higher than
the value of the voltage measured on pin 2 of the thermal sensor, and it relates to the temperature
value in Module 4442 (i.e.: for a temperature of 50˚C, it should measure 5V).
AT7120 Owner Manual Rev. 1.1 – March 2009 40/76
Section 7 – Power Supply
Module 4401
General Functional Description
Power supply - Module 4401 - is the switching type, configured in the topology of half bridge, having
overall efficiency above 80%. Module 4401 is responsible for the generation and distribution of
following voltage DC:
+32V FIXED
+32V RE-CONNECTABLE
+18V
-18V
+9V
Module 4401 can be connected to the electric AC network of 120Vac or 240Vac, according with internal jump
positions.
Module 4401 is self-protected against DC short-circuit. This protection acts by inhibiting the generation of
switching pulses, shutting down the power supply; 0 volts at the DC’s outputs. The output +32V RE-
CONNECTABLE is managed by the Control unit.
The re-connection command is sent to the power supply, to turn the +32V RE-CONNECTABLE on. This voltage
is responsible for feeding the 60W amplifier - Module 4407. The consumption in Amps from the +32V RE-
CONNECTABLE power supply is basically the consumption associated with the drain electrical current of the
LDMOS transistors of the amplifier. Because of this configuration, the LDMOS currents are measured at the
power supply - Module 4401.
These current measurements are routed to the control unit. In case of extreme measured values, the control unit
inhibits the +32 RE-CONNECTABLE power supply.
Module 4401 – Block Diagram
Input AC filter
The C1, C6 and TF-1 components together assemble the line filter. This filter minimizes the noise
generated by the power supply into the AC network.
The varistors V1, V2 and V3 prevent over-voltage damages potentially caused by occurrences on the
AC network.
The group of diodes D1/D4 rectifies the AC voltage from the AC network and delivers this rectified
voltage to the capacitors C9 and C10 for filtering. These capacitors could be connected in parallel or in
series, according with the set of the jumps for 120/240Vac.
AT7120 Owner Manual Rev. 1.1 – March 2009 41/76
The resistances R1 and R2 are the loads for the capacitors C9 and C10 when the power supply is
powered ON. R3 and R4 provoke a fast discharge of C9 and C10 when the power supply is OFF. The
control of the switching function over the PWM modulator is performed by the components TF-3, D5,
D6, D7, R9, T3, C20, C18 and C46.
Switch and Power
The switching function over the DC input voltage is performed by MOSFETs, T1 and T2. The trigger
pulses are generated by integrated circuit CI-1, through the transformer TF-4 that also isolates the
modulation circuit from the AC network.
The switching voltage created by the transistors is applied across the transformer TF-5 to generate the
secondary voltage.
The capacitors C15 and C16 divide the entrance voltage, reducing the voltage over the transistors [seems
unlikely as described]. C14 prevents the direct-current flow towards TF-5.
The noise reduction formed by R7, C17, R34, C31, R37, C35, R43 and C42, help to lower high
frequency noise generated by the fast and short time switching pulses present on the MOSFET
transistors as in TF-4.
Rectification and Filtering
The pulses delivered by switching power devices, are rectified by D8 to D14 and filtered by C32 the
C47. The inductor L2 has multiple sections and stores the transferred energy helping to filter the voltage
provided.
The resistors at the output act as bleeders avoiding undesirable transients and oscillations.
Pulse Width Modulation
This block is composed basically by the integrated circuit CI-1 that performs the PWM switching
process control.
CI-1 output (pins 11 and 14) supply the switching pulses that are applied to the transformer TF-4. The
“Soft-Start" system prevents a fast rise of the output voltage. In this circuit, this function is carried
through by C23.
Feedback
The resistors R10, R13, R12 and TPO-1 form a voltage divider that takes a sample of +32V output of
the power supply and delivers it to CI-1, which compares that with its reference of +5V via R39.
As the result of this sample dictates, the modulation circuit will create a variation in the width of the
switching pulses, thus adjusting the output to maintain a nominal + 32 Vdc.
Protection and Readings
In the event of over-current, in any one of the outputs, the voltage in the inverting input of comparators
CI-3 and CI-4, transferred by the electrical current readings, will be greater that the voltage of reference
in the non inverting entrance.
AT7120 Owner Manual Rev. 1.1 – March 2009 42/76
This event takes the output of the comparator to a low level and will trigger a timer formed by CI-2, R26
and C28 that will shut down, inhibiting the switching process. The electrical current readings are
detected over the power resistors (R44, R45, R36, R40, and R38) and amplified by op-amps end of scale
(4V), proportional to the nominal current of each output. Each electrical current reading has its proper
adjustment:
TPO-2: +32V/10A
TPO-3: +18V/1A
TPO-4: +9V/1A
The output voltage readings are constituted by operational amplifiers (CI-8, CI-9 and CI-10) and each
one is equipped with a TPO for full scale adjustment (4V), proportional to the nominal output voltage.
TPO-5: +32V
TPO-6: +32V RECONNECTED.
TPO-7: -18V
TPO-8: +18V
TPO-9: +9V
Notes
1. The current reading is only for the output voltage of +32V.
2. It does not have reading for the voltage of +32V RECONNECTED.
Reconnection Process
The output of +32V RECONNECTED power supply - Module 4401 - is used to exclusively feed the
UHF amplifier - Module 4407.
The +32V RECONNECTED output is obtained from the +32V FIXED output. This output is enabled or
disabled by control unit - CIP8231 card board - through the reconnect command. In normal conditions,
this command sends +5V to pin 6 of connector CON-8 of CIM3388 (CIP8111) card in Module 4401.
Having this voltage, the switch transistor will be saturated and, consequently, the output voltage of
+32V RECONNECTED will be enabled.
AT7120 Owner Manual Rev. 1.1 – March 2009 43/76
LF353JCI-5
LM393CI-4
LM393CI-3
LM555CI-2
SG3525CI-1
LM358JCI-10
LM358JCI-9
LM358JCI-8
LM353DCI-7
4N28CI-6
IRFP150T4
TIP29CT3
IRFP450T2
IRFP450T1
TRANSFORMER
12V FOR FAN
LINE
FILTER NETWORK
RETIFIER SWITCHING
TRANSISTORS
SWITCHING
RETIFIER INDUCTOR
FILTER
SWITCHING
RETIFIER
PROTECTION
CIRCUIT
ISOLATOR
TRANSFORMER
CONTROL
NETWORK
TRANSFORMER
CONTROL
SUPPLY
(TF-1) (D1-D4) (T1;T2) (TF-5) (D8; D9)
(D10; D11; D12)
(D13;D14)
(L2-A; L2-B)
(L2-C; L2-D;
L2-F)
(C47)
(CI-1)
(TF-4)
(TF-3)
(D5-D7; T3)
(CI-2)
(CI-3) (CI-4)
CURRENT
DETECTION
+32V RESTARTED
+32V
CON-6
1
2GND
TPO-1
ADJUSTMENT +32V
(R35; R36;R44)
(R38)
CON-4 110V
CON-5
CON-3
220V
110/220VAC
CON-1
CON-2
GND
+32V
+18V
+9V
CURRENT
READING
(CI-5; CI-7)
CON-7
123
TPO-3 TPO-4
TPO-9
ADJUSTMENT READING +9V
TPO-8
ADJUSTMENT READING +18V
TPO-7
ADJUSTMENT READING -18V
TPO-5
ADJUSTMENT READING +32V
+9V
+18V
-18V
+32V
FILTER
VOLTAGE
READING
(CI-8; CI-9; CI-10)
SWITCH
TRANSISTOR
(T4)
CON-8
1 2 34 5
RES
6
NC
ISOLATOR
(CI-6) (CI-4A)
CON-12
CON-13
CON-14
+18V
-18V
COMPARATOR
CON-11 +9V
(C32; C33)
(C36; C37)
(C39; C40)
(C43; C44)
TPO-8
TPO-9 TPO-7 TPO-5
+32V
CON-9
CON-10 +GND
+GND
CON-15 +32V
NETWORK
READING
Fig.6.1: Module 4401 Block Diagram
AT7120 Owner Manual Rev. 1.1 – March 2009 44/76
1A
2A
3A
1B
2B
3B
4B
5B
6B
(GY) RESTART PIN 6 –CON-3 –CONTROL UNIT
(RD) +32V READING PIN 9 –CON-9–CONTROL UNIT
(OR) CURRENT READING (+32V) PIN 8 –CON-9 –CONTROL UNIT
CON9
CON10
CON11
CON12
CON13
CON14
CON15
WH) GND
(WH) GND
(GR) +9V
(BL) +18V
(OR) +32V REL
(RD) +32V
CON1
GND
CON2
(BR) AC
(WH) GND
(BK) AC
1
2
CON6
CON7 CON8
CON5
110V
CON4
0V
CON3
220V
(BK) GND FAN
(RD) +12V FAN
TPO-2 TPO-4 TPO-3
TPO-1
TPO-6
TPO-5
TPO-7
TPO-8 TPO-9
(BK) -18V *
CI-1
SG3525
.
10
SDG
T1
SDGT2 D8 D12 D9
VENT.
T3
~ +14V
.
CI-2
0V: normal
1,5V: inhibited switching 0V: normal
5V: inhibited switching
3
TEST OF THE INTERNAL DIODES OF T1 AND T2
SWITCH OFF the power!
Digital Multimeter in the scale of diode test.
Test made with T1 and T2 soldiers in the board
Tip (+) in S and tip (-) in D: ~500
Tip (-) in S and tip (+) in D: infinite resistance
CI-1 SG3525
Switching Pulse11, 14
Shut Down 10
Oscillator5
+4,5V (soft-start)8
Ground (GND)12
+15V (supply)13,15
+5V
2
PINS
16 +5V (reference voltage)
CI-1 pin 14 –OUTPUT +32V WITH LOAD
CI-1 pin 14 –OUTPUT +32V WITHOUT LOAD
TPO-1
Adjustment output voltage +32V
TPO-2
Adjustment reading output current +32V
TPO-3
** Adjustment reading output current +18V
TPO-4
** Adjustment reading output current +9V
TPO-5
Adjustment reading output voltage +32v
TPO-6
** Adjustment reading output voltage +32V RESTART
TPO-7
Adjustment reading output voltage -18V
TPO-8
Adjustment reading output voltage +18V
TPO-9
Adjustment reading output voltage +9V
FUNCTION (MEASURE)
(BK) –18V READING PIN 6 –CON-9 –CONTROL UNIT
(GR) +8V READING PIN 5 –CON-9 –CONTROL UNIT
(BL) +18V READING PIN 7 –CON-9 –CONTROL UNIT
Fig.6.2: Module 4401 – Main components board displacement
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MODULE 4401 – Technical Specifications
FEATURE
SPECIFICATION
INPUT AC VOLTAGE
90 TO 140VAC / 180 TO 250VAC
SWITCHING FREQUENCY
50kHz
LINE REGULATION
BETTER THAN 2% FOR ALL
OUTPUTS
OUTPUTS NOMINAL VOLTAGES
AND CURRENTS
+32V / 10A
+18V / 1A
-18V / 1A
+9V / 1A
RIPPLE
300mV (+32V)
120mV (+18V / +9V)
80mV (-18V)
LOAD REGULATION
BETTER THAN 2% FOR +32V
BETTER THAN 25% FOR +18V,
-18V, +9V
EFFICIENCY
BETTER THAN 80%
OUTPUT OVER CURRENT LIMIT
30% UPPER NOMINAL VALUE
RESTART VOLTAGE
HIGH LEVEL: > 3.5 TO 5Vdc
LOW LEVEL: < 3.3Vdc
SHUTDOWN VOLTAGE
HIGH LEVEL: > 0.7 TO 5Vdc
LOW LEVEL: < 0.7Vdc
POWER SUPPLY
CIRCUIT
CIM
CIP
POWER
3388A
8111A
MODULE 4401 – Changing the Mains Voltage Operation
The module 4401, on its rear side, is built in such way that it is possible to access the 110/220Vac
switching voltage jump. The pictures below illustrate the jump position for each desired operational
voltage. This is the only required maneuver to change the voltage operation on the AT7120 unit.
AT7120 Owner Manual Rev. 1.1 – March 2009 46/76
Fig.6.3: Jump connection for 110Vac operation, (CON5-CON4)
Fig.6.4: Jump connection for 110Vac operation, (CON4-CON3)
Fig.6.5: Module 4401 - +32V Switching Power Supply
AT7120 Owner Manual Rev. 1.1 – March 2009 47/76
Section 8 – DC/DC Converter
Module 4567
General Functional Description
This module generates specific voltages not present at the main power supply - module 4401. The
module 4567 generates +2.5V and +5V, via standard IC regulators, see below:
Fig.7.1: DC/DC Converter Board
CIM3490 (CIP8390)
INPUT
OUTPUT
+18V
+2.5V (CON-2/2)
+5.0V (CON-2/3)
Fuse
+2.5V Output
Brown wire
+5V Output
Yellow wire
+18V Input
GND wire
AT7120 Owner Manual Rev. 1.1 – March 2009 48/76
Section 9 – Memory Interface
Module 3535
General Functional Description
CON-4 and CON-10 at the modulator – Module CIM3510 – are communication connectors with the
memory interface CIP8421 mother board.
Module CIM3516 – General Functional Description
The 1Mbit LUT memory card – Module CIM3516 - is connected to the memory interface - Module
3535. This module holds all the non-volatile data parameters related with the digital linear and non-
linear pre-correction.
Fig.8.1: LUT Memory card & module 3535
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Annex A – AT7120 Operational Software
AT1012_ASM version 1.2
1 Introduction
The LINEAR family of ADVANCED TV transmitter equipment possesses a system for measurement
(measures), configuration (SETUP) and alarms (alarms) controlled by microprocessor system. This
document will demonstrate the navigation, operation and configuration of these functions.
2 Navigation and Signals
2.1 Keypad and Display
2.1.1 Keypad
↑ Moves the cursor up
→ Moves the cursor right
← Moves the cursor left
↓ Moves the cursor down
Yellow Key (Center) “ENTER”
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2.2 Display
The display navigation works as follows:
The cursor must be located on the first character of each function to access that function
It is then activated by pressing the yellow “ENTER” key
During the navigation, special functions will appear in the display to assist the user, these are:
ESC – Used to return to the previous menu
NXT – Used to access the next screen
CLEAR – Used to clear old alarms
2.3 Signals
During the navigation, special characters will appear in the display, these are:
* – Indicates the presence of a current alarm
# – Indicates the presence of an old alarm
(LOCK) – Indicates that the equipment is configured with password, and to access that
part of the menu, the password must be entered.
– The UP and DOWN arrows assist in the navigation between screens. When they appear,
the UP or DOWN key must be used to move between screens. If in a measurement screen, to return to
the previous menu, any key can be pressed.
3 Screen Flow Charts
3.1 Main screens
Main screens
MEASURES SETUP
NXT ESC
MEASURES SETUP
NXT ESC
MEASURES SETUP
NXT ESC
LINEAR INDUSTRIES
INC.
AT720P
MEASURES SETUP
NXT
ESC
ALARMS
REMOTE
NXT
ESC
[
Esc
]
[
Esc
]
[
Any
Key
]
LINEAR INDUSTRIES
INC.
LINEAR INDUSTRIES
INC.
AT7120
MEASURES SETUP
NXT
ESC
MEASURES SETUP
NXT
ESC
MEASURES SETUP
NXT
ESC
ALARMS
REMOTE
NXT
ESC
ALARMS
REMOTE
NXT
ESC
ALARMS
REMOTE
NXT
ESC
[
Esc
]
[
Esc
]
[
Any
Key
]
AT7120 Owner Manual Rev. 1.1 – March 2009 51/76
3.2 Measurement Screen 1
MEASURES SETUP
NXT ESC
POWER P.SUPPLY
NXT ESC
FWD. PWR.: W
RFL. PWR.: W
ALC STATUS:
ALC R.V: V
P.A. TEMPERATURE:
+32V: + V
+18V: + V
+ 9V: + V
-18V: - V
I1: A
[Measures ]
[Esc]
[Power ] [P.Supply ]
[Up and Down Keys ]
[Enter Key ]
MEASURES SETUP
NXT ESC
MEASURES SETUP
NXT ESC
MEASURES SETUP
NXT ESC
POWER P.SUPPLY
NXT ESC
POWER P.SUPPLY
NXT ESC
FWD. PWR.: W
RFL. PWR.: W
FWD. PWR.: W
RFL. PWR.: W
ALC STATUS:
ALC R.V: V
ALC STATUS:
ALC R.V: V
P.A. TEMPERATURE:P.A. TEMPERATURE:
+32V: + V
+18V: + V
+32V: + V
+18V: + V+18V: + V
+ 9V: + V
-18V: - V
+ 9V: + V
-18V: - V
I1: AI1: A
[Measures ]
[Esc]
[Power ] [P.Supply ]
[Up and Down Keys ]
[Enter Key ]
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3.3 Measurement Screen 2
TR.STR. STATUS
NXT SOFTWARE ESC
DATA PACKETS RATE:
Mbps
NULL PACKETS RATE:
Mbps
FIFO OCCUPATION:
%
TRANSPORT STREAM:
SOFTWARE:
VERSION:
PASSWORD ON:
PILOT LEVEL:
CHANNEL:
LO N.I: mV
LO N.Q: mV
TX.BAL.I:
PHASE I:
TX.BAL.Q:
PHASE Q:
DPD SCALE :
DPD ACTIVE:
[Status ][Tr.Stream ]
[Up and Down keys ]
[Enter Key]
[Software ]
TR.STR. STATUS
NXT SOFTWARE ESC
DATA PACKETS RATE:
Mbps
NULL PACKETS RATE:
Mbps
FIFO OCCUPATION:
%
TRANSPORT STREAM:
SOFTWARE:
VERSION:
PASSWORD ON:
PILOT LEVEL:
CHANNEL:
LO N.I: mV
LO N.Q: mV
TX.BAL.I:
PHASE I:
TX.BAL.Q:
PHASE Q:
DPD SCALE :
DPD ACTIVE:
[Status ][Tr.Stream ]
[Up and Down keys ]
[Enter Key]
[Software ]
TR.STR. STATUS
NXT SOFTWARE ESC
TR.STR. STATUS
NXT SOFTWARE ESC
DATA PACKETS RATE:
Mbps
DATA PACKETS RATE:
Mbps
NULL PACKETS RATE:
Mbps
NULL PACKETS RATE:
Mbps
FIFO OCCUPATION:
%
FIFO OCCUPATION:
%
TRANSPORT STREAM:TRANSPORT STREAM:
SOFTWARE:
VERSION:
SOFTWARE:
VERSION:
PASSWORD ON:PASSWORD ON:
PILOT LEVEL:PILOT LEVEL:
CHANNEL:CHANNEL:
LO N.I: mV
LO N.Q: mV
LO N.I: mV
LO N.Q: mV
TX.BAL.I:
PHASE I:
TX.BAL.I:
PHASE I:
TX.BAL.Q:
PHASE Q:
TX.BAL.Q:
PHASE Q:
DPD SCALE :
DPD ACTIVE:
DPD SCALE :
DPD ACTIVE:
[Status ][Tr.Stream ]
[Up and Down keys ]
[Enter Key]
[Software ]
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3.4 Configuration Screen
[Enter Key]
MEASURES SETUP
NXT ESC
TYPE PASSWORD:
NXT YES PREV ESC
WRONG PASSWORD !
TYPE PASSWORD:
ENABLE PASSWORD:
YES NO
TYPE PILOT LEVEL:
TYPE CHANNEL:
FACTORY SETUP
TYPE LO NULL I:
TYPE LO NULL Q:
TYPE AMPLITUDE I:
TYPE PHASE I:
TYPE AMPLITUDE Q:
TYPE PHASE Q:
TYPE DPD SCALE:
DPD ACTIVE:
YES NO
ALC. R.V.: [V]
POWER : [W]
TYPE CONFIG.:
[Yes]
[Enter Key ]
[Wrong Password and Enter Key ]
[Correct Password
and Enter Key ]
[Esc]
[Enter Key]
MEASURES SETUP
NXT ESC
MEASURES SETUP
NXT ESC
MEASURES SETUP
NXT ESC
TYPE PASSWORD:TYPE PASSWORD:
NXT YES PREV ESCNXT YES PREV ESC
WRONG PASSWORD !WRONG PASSWORD !
TYPE PASSWORD:TYPE PASSWORD:
ENABLE PASSWORD:
YES NO
ENABLE PASSWORD:
YES NO
TYPE PILOT LEVEL:TYPE PILOT LEVEL:
TYPE CHANNEL:
FACTORY SETUP
TYPE CHANNEL:
FACTORY SETUP
TYPE LO NULL I:TYPE LO NULL I:
TYPE LO NULL Q:TYPE LO NULL Q:
TYPE AMPLITUDE I:TYPE AMPLITUDE I:
TYPE PHASE I:TYPE PHASE I:
TYPE AMPLITUDE Q:TYPE AMPLITUDE Q:
TYPE PHASE Q:TYPE PHASE Q:
TYPE DPD SCALE:TYPE DPD SCALE:
DPD ACTIVE:
YES NO
DPD ACTIVE:DPD ACTIVE:
YES NO
ALC. R.V.: [V]
POWER : [W]
ALC. R.V.: [V]
POWER : [W]
TYPE CONFIG.:TYPE CONFIG.:
[Yes]
[Enter Key ]
[Wrong Password and Enter Key ]
[Correct Password
and Enter Key ]
[Esc]
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3.5 Alarm Screen
4 Initialization
When the equipment is initially switched on, the screen backlight lights automatically and the message
“LOADING”… is displayed, indicating the load process of the modulator has begun. In the unlikely
case that the equipment continues showing this message, the possibility of software error has occurred in
the load process of the modulator and the equipment may not enter into correct operation. Please report
this status to Linear Industries Inc to get the necessary steps of action. Following the LOADING
message, the name of the manufacturer, the type number of the equipment, normal rated RMS power
and the operating channel are displayed.
This information alternates approximately every 2 seconds. The backlight switches off after
approximately 20 seconds. After the initialization of the equipment, this first information will remain
indefinitely until another key is pressed. When pressing another key the backlight will light again.
Depending on the type of screen the cursor will automatically locate itself in one of the options. To
execute some of these options, after the backlight has extinguished it may be necessary to press any key
again. If no option is chosen, the backlight will switch off in approximately 20 seconds and then after
approximately five minutes the screen returns to the initial display.
ALARMS REMOTE
NXT ESC
CURRENT PAST
ESC
NXT CLR. ALL ESC
NXT ESC
[Esc]
[Alarms ][Past]
[Esc]
[Current ][Esc]
ALARMS REMOTE
NXT ESC
ALARMS REMOTE
NXT ESC
ALARMS REMOTE
NXT ESC
CURRENT PAST
ESC
CURRENT PAST
ESC
NXT CLR. ALL ESCNXT CLR. ALL ESC
NXT ESC
NXT ESC
NXT ESC
[Esc]
[Alarms ][Past]
[Esc]
[Current ][Esc]
AT7120
120W
LINEAR INDUSTRIES
INC.
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4.1 MEASURE MENU
The measure menu allows access to the general equipment configuration parameters; power levels, TS
feed and status, qualification of passwords, cancellation of the L.O signal., rejection of image frequency
signal, level of scale, activation of look up tables (LUTs) for pre-distortion and the name and version of
the installed software on the central microcontroller.
Navigation through these screens is done by pressing the keys UP and DOWN. When these are
displayed it is not possible to configure any parameters. The “ENTER” key must be pressed to return to
the main screen.
4.1.1 POWER MENU
The power menu displays the forward and reflected power at the output of the equipment, measured at
the output power reflectometer. Also displayed are the ALC reference voltage and the temperature of the
final RF output amplifier.
To have access to the POWER screen, the following sequence of screens is necessary:
Access MEASURES
Access POWER
Use the key “DOWN” to see the next set of screens.
To return to the previous screen, press the UP key. To return to the POWER option presses “ENTER”.
NOTE: The screens above are a rolling type, allowing access to all of the voltage measurements by
using the UP and DOWN keys.
4.1.2 POWER SUPPLY MENU
This screen displays the voltages and currents of the main equipment power supplies.
POWER P.SUPPLY
NXT ESC
POWER P.SUPPLY
NXT ESC
FWD. PWR.: W
RFL. PWR.: W
ALC STATUS:
ALC R.V: V
P.A. TEMPERATURE:
FWD. PWR.: W
RFL. PWR.: W
FWD. PWR.: W
RFL. PWR.: W
ALC STATUS:
ALC R.V: V
ALC STATUS:
ALC R.V: V
P.A. TEMPERATURE:P.A. TEMPERATURE:
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To have access to the P.SUPPLY screen the sequence of screens are:
Access MEASURES
Access P.SUPPLY
Use the key “UP and DOWN” to move between screens.
To return to the previous screen press the key UP. To return to the option P.SUPPLY press “ENTER”.
4.1.3 MENU ESC
Pressing ESC returns the cursor to the previous screen.
4.1.4 MENU NXT
Selecting the “NXT” option provides access to more options of measurement. The sequence for access
of these measurements is shown below:
4.1.5 MENU TR.STR.
TR STR shows information about the input digital signal.
MEASURES SETUP
NXT ESC
MEASURES SETUP
NXT ESC
MEASURES SETUP
NXT ESC
POWER P.SUPPLY
NXT ESC
POWER P.SUPPLY
NXT ESC
MEASURES SETUP
NXT ESC
MEASURES SETUP
NXT ESC
MEASURES SETUP
NXT ESC
+32V: + V
+18V: + V
+ 9V: + V
-18V: + V
I1: A
+32V: + V
+18V: + V
+32V: + V
+18V: + V+18V: + V
+ 9V: + V
-18V: + V
+ 9V: + V
-18V: + V
I1: AI1: A
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Select NXT and press ENTER
Select TR.STR and press ENTER
To return to the previous screen press the UP key. To return to the TR.STR options press ENTER.
4.1.6 MENU STATUS
4.1.6.1 Password qualification state
This screen shows the information on the configured parameters:
PASSWORD ON: YES - indicates that a password is required to enter into the SETUP MENU, and the
user will be asked for it each time this menu is accessed.
PASSWORD ON: NO - indicates that the requirement of a password is not necessary to enter into the
SETUP MENU and open access is available.
TR.STR. STATUS
NXT SOFTWARE ESC
TR.STR. STATUS
NXT SOFTWARE ESC
DATA PACKETS RATE:
Mbps
NULL PACKETS RATE:
Mbps
FIFO OCCUPATION:
%
TRANSPORT STREAM:
DATA PACKETS RATE:
Mbps
DATA PACKETS RATE:
Mbps
NULL PACKETS RATE:
Mbps
NULL PACKETS RATE:
Mbps
FIFO OCCUPATION:
%
FIFO OCCUPATION:
%
TRANSPORT STREAM:TRANSPORT STREAM:
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Below is the sequence necessary for this option:
Select STATUS and press ENTER
4.1.6.2 Amplitude level of the ATSC Pilot carrier
This is a numerical value relative to the carrier pilot level.
PILOT LEVEL: <+511 TO -2048>
Access to the STATUS menu can be via the far left option or from the PASSWORD ON screen:
following viewing the programmed level press the UP and DOWN keys to navigate to other STATUS
screens.
4.1.6.3 Transmission channel
This screen displays the factory programmed transmission channel.
CHANNEL <2 to 53>
To have access to this menu, navigate via the STATUS option and then select PILOT LEVEL, press the
UP and DOWN key and then the factory programmed channel can be viewed.
TR.STR. STATUS
NXT SOFTWARE ESC
TR.STR. STATUS
NXT SOFTWARE ESC
PASSWORD ON:PASSWORD ON:
PASSWORD ON:
PILOT LEVEL:
PASSWORD ON:PASSWORD ON:
PILOT LEVEL:PILOT LEVEL:
PILOT LEVEL:
CHANNEL:
PILOT LEVEL:PILOT LEVEL:
CHANNEL:CHANNEL:
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4.1.6.4 DC voltage level adjustment for the cancellation of the L.O signal
This level indicates the voltage programmed in the Up Converter for the cancellation of the local
oscillator signal.
LO N.I.: and LO N.Q. <0.00 to 49.75 mV>:
To have access to this menu, select the option STATUSCHANNEL, press UP and DOWN key
4.1.6.5 Rejection of the frequency image
The following are numerical values related to the amplitude and phase signal for rejection of the image
frequency.
TX. BAL. Q: - <00000 to 32767>
PHASE Q: - <-32767 to +32767>
TX. BAL. I: - <00000 to 32767>
PHASE I: - <-32767 to +32767>
4.1.6.6 Pre-distortion scale level
This is a scale (or intensity) of the pre-distortion level applied to the transmission signal.
DPD SCALE: < 0000 to 4095>
TX.BAL.Q:
PHASE Q:
DPD SCALE :
DPD ACTIVE:
TX.BAL.Q:
PHASE Q:
TX.BAL.Q:
PHASE Q:
DPD SCALE :
DPD ACTIVE:
DPD SCALE :
DPD ACTIVE:
CHANNEL:
LO N.I: mV
LO N.Q: mV
CHANNEL:CHANNEL:
LO N.I: mV
LO N.Q: mV
LO N.I: mV
LO N.Q: mV
LO N.I: mV
LO N.Q: mV
TX.BAL.I:
PHASE I:
TX.BAL.Q:
PHASE Q:
LO N.I: mV
LO N.Q: mV
LO N.I: mV
LO N.Q: mV
TX.BAL.I:
PHASE I:
TX.BAL.I:
PHASE I:
TX.BAL.Q:
PHASE Q:
TX.BAL.Q:
PHASE Q:
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4.1.6.7 Qualification of pre-distortion tables
DPD ACTIVE: YES – indicates the signal pre-distortion tables are active
DPD ACTIVE: NO - - indicates the signal pre-distortion tables are not active.
4.1.6.8 Name and version of software
This menu indicates the name and the version of recorded software in the central microcontroller. This
information must be provided to the factory in the case of any maintenance request.
SOFTWARE: < ATXXXX >
VERSION: < X.X >
To verify the name and version of software select do the following:
Select SOFTWARE and press ENTER
4.2 MENU SETUP
This menu allows access to the configuration functions and parameters of operation of the equipment.
The RIGTH ARROW and LEFT ARROW keys locate the cursor in each one of the four possible digits.
The “+” and “-” keys, the ENTER and UP and DOWN keys change the digits. The “ENTER” key
finalizes the numerical value to the control system. Without pressing the “ENTER” key the value is not
saved. Before the “ENTER” key is pressed the parameter is only adjusted in real time for review of the
measured results. If the equipment is switched off during a parameter configuration before pressing the
“ENTER” key, the configuration will not be saved in the memory and the same values will be as
previously stored.
4.2.1 MENU TYPE PASSWORD
This menu sets the four numerical password digits that give access to the SETUP functions. This menu
is active only when option YES in the ENABLE PASSWORD menu is indicated. The RIGTH ARROW
and LEFT ARROW keys position the cursor in each one of the four possible digits and the ENTER and
SOFTWARE:
VERSION:
SOFTWARE:
VERSION:
TX.BAL.Q:
PHASE Q:
DPD SCALE :
DPD ACTIVE:
TX.BAL.Q:
PHASE Q:
TX.BAL.Q:
PHASE Q:
DPD SCALE :
DPD ACTIVE:
DPD SCALE :
DPD ACTIVE:
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UP and DOWN keys edit the digits. The “ENTER” key transmits the value of the password to the
control system.
It is only possible to leave this screen after entering the numerical password.
If the correct password is entered, access to the SETUP options is available. If the incorrect password is
entered, the following is message is shown “WRONG PASSWORD” and the equipment returns
automatically to the main options menu.
TYPE PASSWORD: <XXXX>
Below is the sequence of access for this menu:
Select SETUP and press ENTER
Type the password number and then press “ENTER”
4.2.2 LIST OF MENU OPTIONS
The following allows navigation in the equipment configuration options:
NXT: executes the navigation option
PREV: returns to the previous menu
YES: indicates access to that particular option
ESC: returns to the main options menu
To see the options select NXT and press “ENTER”. When the required option is shown, locate the
cursor on the “YES” and press “ENTER”.
4.2.2.1 < SET NEW PASSWORD? >
This menu allows the four numerical digits to be configured as a new password for the equipment. The
RIGTH ARROW and LEFT ARROW keys locate the cursor on one of the four digits to be changed and
the ENTER and UP and DOWN keys change the digits. Pressing “ENTER” key then informs the new
password to the control system and returns to the main options menu.
TYPE PASSWORD:TYPE PASSWORD:
NXT YES PREV ESCNXT YES PREV ESC
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It is only possible to leave this screen after entering the numerical password.
4.2.2.2 < ENABLE PASSWORD? >
This option allows the qualification or not of the password programmed in SET NEW PASSWORD
option.
YES: confirms the requirement of the password to have access to the SETUP options menu.
NO: Indicates that no password is required to have access to the SETUP options menu.
4.2.2.3 < SET PILOT LEVEL? >
This option allows the configuration of the desired level of the ATSC signal pilot carrier with the following range
of values: < +511 TO -2048 >.
4.2.2.4 < SET CHANNEL? >
For equipment safety reasons, changing channel is not allowed in the on-site configuration. This procedure can
only be done in the factory. Changing the channel without the permission of a factory trained engineer can
potentially void any warranty on the product.
4.2.2.5 < SET LO NULL I? >
This menu allows the DC voltage adjustment for “nulling” the “I” signal from the local oscillator inter-
modulation in the Up -Converter.
TYPE PASSWORD:TYPE PASSWORD:
ENABLE PASSWORD:
YES NO
ENABLE PASSWORD:
YES NO
TYPE PILOT LEVEL:TYPE PILOT LEVEL:
TYPE CHANNEL:
FACTORY SETUP
TYPE CHANNEL:
FACTORY SETUP
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The adjustment has the following potential values: < 0.00 to 49.75 mV >.
4.2.2.6 < SET LO NULL Q? >
This menu allows the DC voltage adjustment for “nulling” the “Q” signal from the local oscillator (inter-
modulation in the Up-Converter.
The adjustment has the following potential values: < 0.00 to 49.75 mV >.
4.2.2.7 < SET TX BAL. AMP. I? >
This menu allows the adjustment of the “I” amplitude of the image rejection signal in the 8VSB
modulator.
range of values: < 00000 to 32767 >.
4.2.2.8 < SET PHASE I? >
This menu allows the adjustment of the “I” phase of the image rejection signal in the 8VSB modulator.
range of values: < 00000 to 32767 >.
TYPE LO NULL I:TYPE LO NULL I:
TYPE LO NULL Q:TYPE LO NULL Q:
TYPE AMPLITUDE I:TYPE AMPLITUDE I:
TYPE PHASE I:TYPE PHASE I:
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4.2.2.9 < SET TX BAL. AMP. Q? >
This menu allows the adjustment of the “I” balance of the image rejection signal in the 8VSB modulator.
range of values: < 00000 to 32767 >.
4.2.2.10 < SET PHASE Q? >
This menu allows the adjustment of the “Q” phase signal amplitude of image rejection signal in the
8VSB modulator.
range of values: < 00000 to 32767 >.
4.2.2.11 < SET DPD SCALE? >
This menu allows the configuration of the DPD (Digital Pre-distortion) scale (or intensity) of digital pre-
distortion applied to ATSC signal.
range of values : < 0000 to 4095 >
4.2.2.12 < SET DPD ACTIVE? >
This menu allows the activation or not of the digital pre-distortion tables.
YES: activates the use of the digital pre-distortion look up tables (LUT’s)
NO: deactivates the use of the digital pre-distortion look up tables (LUT’s)
4.2.2.13 < SET POWER? >
This allows the configuration of normal rated power at the output of the equipment. The ENTER and UP
and DOWN keys increase and decrease the power level. The RIGTH ARROW and LEFT ARROW keys
do not possess any function in this screen. The “ENTER” key saves the desired value.
TYPE PHASE Q:TYPE PHASE Q:
TYPE DPD SCALE:TYPE DPD SCALE:
DPD ACTIVE:
YES NO
DPD ACTIVE:DPD ACTIVE:
YES NO
ALC. R.V.: [V]
POWER : [W]
ALC. R.V.: [V]
POWER : [W]
TYPE AMPLITUDE Q:
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The power value displayed on this screen is a value fed directly from the output of the reflectometer and
is the same value that is provided to the ALC s (Automatic Level Control) system circuit. The system
allows for a certain flexibility of adjustment by providing at the same time the power level display in
order to verify the actual power level. It is not recommended to adjust for very low values of ALC
voltage as this may cause the power to become unstable.
For higher ALC values (above 1.3V), the power will change with the variation of the ALC voltage. In
case this simultaneous variation does not occur, it is likely that there is a fault in either or both, the Up
Converter or final RF amplifier. This type of occurrence should be reported to the Linear Industries Inc.
In this screen, the ALC is disabled for precision adjustments of the power level and to have full manual
control of power, use the ENTER and UP and DOWN keys. In any another environment or screen, the
ALC system returns to an enabled mode in order to control the power level.
WARNING: It is important not to set the programmed values of the ALC and consequently the final
RF power level above the nominal value of the equipment: This may cause damage to the internal
modules and may void the warranty on the unit.
4.3 ALARMS MENU
This transmission equipment has a system of alarms. These are illustrated by symbols at the right side of
the display screen: * and #. The signal * represents the occurrence of a current alarm. The signal #
represents an old alarm, i.e. an alarm that has already occurred and has been cleared. Under normal
operating conditions neither of these two symbols will be displayed on the screen.
When the * is displayed, the current alarm screen should be accessed to verify which alarm is occurring.
4.3.1 CURRENT MENU
This menu displays the current alarm messages i.e. alarms that are still present and have not yet been
cleared.
The current alarm messages are updated when entering the CURRENT MENU.
To update the list, you must leave the menu screen and then return to the ALARMS using the ESC
option. Then access the CURRENT menu option again.
Option NXT shows the next alarm message. If there are no alarm messages it will read as follows:
< ALARMS LIST START! >
< ALARMS LIST END! >
Option ESC returns to the previous screen.
The following messages may appear on the current alarms list:
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< ALARMS LIST START! >
< OVER FIFO! >
< MPEG LOSS! >
< DWR. NOT PROGRAMMED! >
< TEMPERATURE! >
< LOCK CLOCK! >
< LOCK LO! >
< OUTPUT POWER ZERO! >
< REFLECTED POWER! >
< ALARMS LIST END! >
Below shows the screens necessary to display the CURRENT alarms menu:
Select NXT and press ENTER
Select ALARMS and press ENTER
Select CURRENT and press ENTER
4.3.2 PAST MENU
This menu displays the past or old alarm messages, i.e. alarms that indicate some equipment alarm
occurrence that has been cleared.
MEASURES SETUP
NXT ESC
MEASURES SETUP
NXT ESC
MEASURES SETUP
NXT ESC
ALARMS REMOTE
NXT ESC
ALARMS REMOTE
NXT ESC
ALARMS REMOTE
NXT ESC
CURRENT PAST
ESC
CURRENT PAST
ESC
NXT ESC
NXT ESC
NXT ESC
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The current alarm messages are updated when entering the PAST MENU. To update the list, you must
leave the menu and then return to the ALARMS menu using the ESC option and then access the PAST
menu option again.
Option NXT shows the next alarm message. If there are no alarm messages it will read as follows:
< ALARMS LIST START! >
< ALARMS LIST END! >
Option CLR. ALL erases all the old alarm messages.
These messages are also erased when the equipment is turned off. Option ESC returns to the previous
screen.
The follow are messages that can appear in the past alarms list:
< ALARMS LIST START! >
< OVER FIFO! >
< MPEG LOSS! >
< DWR. NOT PROGRAMMED! >
< TEMPERATURE! >
< LOCK CLOCK! >
< LOCK LO! >
< OUTPUT POWER ZERO! >
< REFLECTED POWER! >
< ALARMS LIST END! >
Below are the screens necessary to display the PAST alarms menu:
Select NXT and press ENTER
Select ALARMS and press ENTER
Select PAST and press ENTER
MEASURES SETUP
NXT ESC
MEASURES SETUP
NXT ESC
MEASURES SETUP
NXT ESC
ALARMS REMOTE
NXT ESC
ALARMS REMOTE
NXT ESC
ALARMS REMOTE
NXT ESC
CURRENT PAST
ESC
CURRENT PAST
ESC
NXT CLR. ALL ESCNXT CLR. ALL ESC
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4.4 Remote Menu
It allows the display of the parameters to be configured in the Windows® Hyper-terminal emulator in
order to connect a computer with an RS232 port and have access to the configuration and monitoring of
the equipment.
5. Operation of the Hyper-terminal
The AT7120 transmitter system parameters can be monitored and configured using the Windows®
Hyper-terminal. The range of values is the same as described previously in the equipment front panel
operation (LCD display and keys). It is possible to adjust the transmitter power with the Hyper-terminal
interface, however, the ALC system must be first disconnected using the equipment front panel and only
within the limits set from the front panel configuration.
The password configuration process is the same as described for the front panel configuration. The
password can be accepted or not, and when accepted, it allows access to the SETUP environment. In the
SETUP environment it is possible to enable or to disable the password and also to choose a new
password. The insertion of new password occurs with the cursor automatically moving to the next digit
when the highest value has been reached. After reaching the desired number the cursor is moved
automatically to the right, and after the last digit is reached the next typed key returns to the first
position.
A cable must be connected between the transmitter RS232 output and RS232 input of the computer. The
cable end for the computer is a male DB-9 and the cable end for the transmitter is a female DB-9
connector. Only three of the nine pins are used, with pins 2 and 3 of the cable crossed. Pins used are TX,
RX and GND. Pin 3 is TX and pin 2 is RX. In the both connectors pin 5 is GND. The figure below
illustrates the RS232 cable and connector:
The configuration of the Window® Hyper-terminal must be in accordance with following:
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PROPERTIES OF COM4
Configuration of Port
Bits per Second 19200
Bits of data 8
Parity None
Bits of Parity 1
Flow Control None
To access the data of the equipment and to bring up to date the screens in the Hyper-terminal use
ENTER on the keyboard. Screen 1 indicates some measurements, states of the alarms and offers options
for access to other functions of the equipment.
(Typical example of screen shot)
When the password of the equipment is qualified screen 2 will be displayed. A password of 4 digits
must be entered to access the SETUP environment. In the case where the typed password is incorrect,
the message “WRONG PASSWORD" will be shown. When the password is correct a warning question
is asked. Reply YES (y), which then allows access to the SETUP environment. A NO (n) reply will
return to the menu to the previous screen 1.
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(Typical example of screen shot)
(Typical example of screen shot)
To configure the parameters of screen 3 the characters in the parentheses should be selected by using
standard keyboard keys. Select the option desired and then use the keyboard characters U (up) and D
(down) or Y (Yes) or N (No) to display the values of the configuration. For safety reasons, the values
entered are only confirmed when exiting from the screen. Exit from the screen by using the ESC key.
The W key will refresh the screen.
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(Typical example of screen shot)
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Annex B – Checking the RF Power LDMOS
Transistors
All 3 main RF transistors on the module 4407 are LDMOS technology type. The manipulation of these transistors
requires some special care, for instance, avoiding manual bare finger direct contact with the parts. Instead,
prioritize the usage of metal parts tools and grounded care procedures.
Gate-to-ground conductance test
With the transistors in place, it is possible with a digital multimeter to perform this test. Unplug the DC
connectors (CON-2 and CON-3) and measure the conductance between the gate terminal and ground.
T1:
Adjust TPO-1 for the minimum of its value (counterclockwise); the reading at the multimeter should be
close of 380Ω. Adjusting TPO-1 for the maximum of its value, the reading at the multimeter should be
close of 720Ω.
T2:
Adjust TPO-2 for the minimum of its value (counterclockwise); the reading at the multimeter should be
close of 370Ω. Adjusting TPO-1 for the maximum of its value, the reading at the multimeter should be
close of 720Ω.
T3:
Adjust TPO-3 for the minimum of its value (counterclockwise); the reading at the multimeter should be
close of 550Ω. Adjusting TPO-1 for the maximum of its value, the reading at the multimeter should be
close of 705Ω. These readings are expected to remain the same for both T3 gates.
In event that these measurements do not come true, check the possibility of some surrounding
components being damaged, and/or initiate a careful visual inspection, looking for abnormal
circumstances. Some tests suggested above could be repeated with the transistors detached out from the
PCB board; in this case, measurement readings for gate-to-ground should be close of 40MΩ. Also in this
situation, detect a diode type behavior by measuring drain-to-source conductance as follows:
(+)
DRAIN
(-)
SOURCE
R=
580Ω
(+)
SOURCE
(-)
DRAIN
R=
∞
In case these 2 measurements cannot be verified, the transistor must be substituted.
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Annex C – Typical Final Test Reports
Results
Out of Channel Emissions
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Frequency Response and Group Delay
Carrier Phase Noise
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Digital Modulation Error Rate
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Conducted Spurious Emissions