IP Mobilenet ECSDR4BSTX UHF Base Station Data Radio User Manual 281725
IP Mobilenet, LLC UHF Base Station Data Radio 281725
Manual
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| Document ID | 281725 |
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| Date Submitted | 2002-11-06 00:00:00 |
| Date Available | 2002-11-06 00:00:00 |
| Creation Date | 2002-11-06 18:05:35 |
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400 - 512 MHz Base Station Data Radio Owner’s Manual Date Prepared: March 1, 2000 Document Control #: DC-95 Version: C-1 (Special Release) Copyright 2000-2002 IP MobileNet, Inc. 16842 Von Karman Avenue, Suite 200 Irvine, CA 92606 Voice: (949) 417-4590 Fax: (949) 417-4591 TABLE OF CONTENTS SECTION 1: THEORY OF OPERATION .................................................................................. 3 General Block Diagram ........................................................................................................... 3 General Block Diagram Definitions ................................................................................ 3 DR4B Base Station Data Radio Circuitry ....................................................................... 5 System Controller ................................................................................................ 5 Input/Output ......................................................................................................... 5 Modem Switching................................................................................................. 6 Modem ................................................................................................................. 6 Diversity Reception Controller ............................................................................. 6 Receive Signal Strength Indication Comparator .................................................. 7 Baseband............................................................................................................. 8 Receiver Board .................................................................................................... 8 IF Amplifier........................................................................................................... 9 Receiver Injection ................................................................................................ 9 Exciter ................................................................................................................ 10 Analog Modulation ............................................................................................. 10 Phase Locked Loop ........................................................................................... 11 Power Amplifier.................................................................................................. 11 SECTION 2: FACTORY TEST PROCEDURE ........................................................................ 12 Equipment List ........................................................................................................... 12 Programming and Configuring the Base Station Data Radio ................................ 13 Adjustment / Alignment Procedure .......................................................................... 14 Receiver Injection ............................................................................................. 14 Receiver 1 ........................................................................................................ 14 Diversity Reception Controller .......................................................................... 14 Receive Data.................................................................................................... 15 Exciter ............................................................................................................ 16 Power Amplifier ................................................................................................ 16 SECTION 3: FCC LABEL ....................................................................................................... 17 DR4B Base Station Data Radio FCC Label Placement ........................................... 17 DR4B Base Station Data Radio FCC Label .............................................................. 17 APPENDIX A: DR4B BASE STATION DATA RADIO CIRCUIT BOARD DIAGRAM............ 18 ~\Technical Documentation\System Manuals\FCC-Reports\IP1B-FCCRpt.doc Page 2 SECTION 1: THEORY OF OPERATION General Block Diagram General Block Diagram Definitions For increased data security, the modem supports the U.S. Government developed Digital Encryption Standard (DES) data encryption and decryption protocols. The standard Base Station Data Radio circuit board contains eight (8) sections defined below: Input/Output Circuitry associated with the base station’s DB25 data connector providing all of the RS232 data and handshake functions, including the necessary RS232 to logic level changes. System Controller Manages the operation of the base station loading selected transmit/ receive frequencies into the injection synthesizer, controls the operation of the modem and provides transmit timeout protection in the event a fault causes the radio to become stuck in the transmit mode. Includes memory for storage of base station operating parameters. Electrically erasable programmable read only memory (EEPROM) is used to store parameters entered by the technician such as channel numbers and RX/TX frequencies. This information is retained after power is removed from the base station. Transmit Processing Circuitry, which amplifies the analog audio signal from the modem and uses it to modulate a voltage-controlled oscillator (VCO) and reference oscillator in the transmitter synthesizer section. Modulating the VCO and reference oscillator simultaneously results in a higher quality FM signal. ~\Technical Documentation\System Manuals\FCC-Reports\DR4B-FCCRpt.doc Page 3 SECTION 1: THEORY OF OPERATION Modem Converts parallel data into an analog audio waveform for transmission and analog audio from the receiver to serial data. Serial data appears on the base station’s DB25 serial port. The radio supports a 115.2 KBPS data transmission rate on the serial port, SLIP protocol, and a 19.2 KBPS OR 9.6 KBPS over-theair data transmission rate. Within a single chip the modem provides forward error correction and detection, bit interleaving for more robust data communications, and third generation collision detection and correction capabilities. Synthesizers Provides ultra stable signals for the three (3) receivers and the transmitter. Two (2) independent synthesizers are used in the base station to obtain full duplex (simultaneous receive and transmit) operations. Both synthesizers incorporate phase lock loop (PLL) technology and use separate reference oscillators. RX Synthesizer The receive synthesizer provides a local oscillator signal 45 MHz above or below the desired receive channel frequency. This is called high side injection or low side injection. TX Synthesizer The transmit synthesizer produces the desired frequency by controlling a VCO. The VCO and the reference oscillator are both frequency modulated by the modem output. Diversity Reception Controller Circuitry selects one of three diversity receiver audio outputs for processing by the modem by comparing the Received Signal Strength Indication (RSSI) output from each receiver. Essentially, audio from the receiver with the highest RSSI value is passed on to the modem. Transmitter Consists of an exciter and a power amplifier module covering various frequency bands in segments. A different power amplifier module is required for each segment. The transmitter power control is included with the power supply circuitry on the same board. Receiver 1/Receiver 2/ Receiver 3 Uses three (3) discrete receivers tuned to the same frequency. The three (3) receivers are required to support IPMN’s base station DRS. NOTE: Some installations use only two (2) receivers. The receivers are double-conversion superhetrodynes with an Intermediate Frequency (IF) of 45 MHz. Each receiver consist of bandpass filters, RF amplifiers, a mixer, 45 MHz crystal filter, and a one-chip IF system. The injection synthesizer provides the first local oscillator signal and outputs from each receiver including RSSI and analog audio for the diversity reception controller. Power Supply Power supply circuitry derives the various operating voltages required by the base station. Fixed voltage regulators are employed through the radio for this purpose. ~\Technical Documentation\System Manuals\FCC-Reports\DR4B-FCCRpt.doc Page 4 SECTION 1: THEORY OF OPERATION DR4B Base Station Data Radio Circuitry The DR4B Base Station Data Radio works within the frequency range of 400-512 MHz. The following section provides detail views, descriptions, and key areas on the DR4B Base Station Data Radio circuit board especially useful during troubleshooting. System Controller This section displays the Central Processing Unit (CPU)(U1), clock, and power-on reset circuitry. It provides more processing power than required for future capabilities to be incorporated into the radio without changing processors. Such capabilities include data encryption/decryption (DES), remote fault monitoring, etc. U1 features a 16-bit address bus and 128K of internal flash random access memory (RAM). To enter the programming mode it is necessary to reset the switch (S1) and power up again. CPU operations are controlled by Y2 an 4.9152 MHz clock module. Capacitor (C1) and an internal Schmidt trigger circuit inside of U1 generates the power on reset signal. The RESET* output from U1 drives a latch and decoder found elsewhere on the board. This section displays the RAM, decoder, EEPROM, and programming power supply circuitry. U2 is a 512K x 8 bit static RAM chip, which provides temporary storage of radio configuration data while the power is on. This is necessary in order to program the radio configuration. U2 is controlled directly by the address, data, and control busses from the CPU. Chip U5 decodes the A11-A14 address bus to provide chip selects for the modem and EEPROM memory. Chip U6 is an 8-bit latch. It latches inputs from the D0-D7 bus and lights the front panel status indicators (TX, CD, RX1, RX2, and RX3). Chip U3 is a serial EEPROM, which provides 2K bits of pre-programmed data storage for the CPU. Data is clocked out of U3 by EECLK, and back into the CPU via EEDATA. A programming power supply is required for the flash RAM inside of the CPU, and this function is performed by U4. This chip is an adjustable voltage regulator with a shutdown control. Resistors R8 and R9 set the output voltage. When the radio configuration data is to be stored in flash RAM, the CPU makes VPP_ENABLE high. This turns on the regulator, producing a 12-volt output via VPP for the flash RAM. This section displays a dedicated processor and voltage regulator. Chip U7 is an optional processor, which permits manual keyboard operation of the radio. It is not used, and may not be installed on the board. Regulator U10 provides 5 volts DC power for all logic circuitry on the System Controller Board. Input/Output This section displays the CPU input/output circuitry. Chip U11 is an RS232 transmitter/receiver, which interfaces the CPU to the Diversity Reception Board via J6. From there, the RS232 data goes directly to a rear panel DB25 connector. U11 converts 5-volt logic-level data to +/-12 volt data in RS232C form, and vice-versa. A charge pump power supply on the chip converts the +5 volt DC power to the +/-12 volt levels required. The charge pump uses capacitors (C28 to C31) to generate voltages. The RS232 serial port data transmission rate of the base station is 115.2 KBPS. ~\Technical Documentation\System Manuals\FCC-Reports\DR4B-FCCRpt.doc Page 5 SECTION 1: THEORY OF OPERATION Modem Switching This section displays the connector wiring and modem switching circuitry. Connector J2 is routed to the front-panel TX, CD, and RX1-RX3 LED indicators. The radio will also accept modulation from an external source (modem or amplified microphone audio). Modem This base station uses separate modems for receive and transmit functions so that full-duplex operation may be obtained. The A0-A1 address bus in addition to the individual read (RD*), write (WR*), and chip select (MODEMTXCS*) lines control all three (3) modems. Modem operations are timed by Y2, a 4.9152 MHZ clock module. Modem chip U14 is dedicated to the transmit operation. Data from the D0-D7 bus is read by the chip, and then converted to a 4-level FSK analog signal, which appears on the TXOUT pin. Op amp U21B buffers the signal, which becomes the MODEM_TXMOD output. From this point, the signal is routed to the modulation circuitry on the Exciter Board. Chip U14 has the ability to demodulate receiver audio, although this capability is not used in most systems. Incoming data-bearing audio from the Diversity Reception Controller Board (and selected receiver) appears at DISC_AUDIO. The signal passes through resistor R54 and into the modem chip. Resistor R52 and capacitor C41 serve as feedback elements, limiting both the gain and bandwidth of an amplifier within U14. The modem chip demodulates the audio into 8 bits of data, which exit U14 on the D0-D7 bus. Chip U14 also provides a bias voltage for the analog circuitry on the Exciter Board. This voltage is about 2.5 volts DC, and it appears on the VBIAS line. The purpose of VBIAS is to bias the Exciter Board analog circuitry for proper operation. Please note that if this voltage is low or missing, the Exciter Board circuitry may not work. Modem chip U15 is dedicated to the receive operation. Incoming data-bearing audio from the Diversity Reception Controller Board (and selected receiver) appears at DISC_ AUDIO. The signal passes through resistor R56 and into the modem chip. Resistor R55 and capacitor C46 serve as feedback elements, limiting both the gain and bandwidth of an amplifier within U15. The modem chip breaks down the audio into 8 bits of data, which exit U15 on the D0-D7 bus. Modem chip U16 is also dedicated to the receive operation, although it may not be used in this application. The operation of U16 is exactly the same as U15. Diversity Reception Controller Board This section displays the power supply circuitry and input/output connector wiring. The power supply consists of a diode (CR1), metal oxide varistor (MOV) (CR2), a fuse (F1), and voltage regulators (VR2 and VR3). 13.8 volts DC from the radio’s power connector appears on the anode of CR1. CR1 provides reverse polarity protection, while CR2 absorbs any damaging transient spikes, which appear on the unregulated supply line. F1 provides over-current protection. The SWB+ output powers the remaining boards in the radio, with the exception of the power amplifier module. VR2 provides a 5-volt DC source for all of the circuitry on the Diversity Reception Controller Board. VR3 provides 5 volts DC for the three receiver boards via a connector (TB1). Two (2) 16-pin DIP headers connect this board to the System Controller Board. One header (J2) provides power and control signals for the System Controller Board. The ALARMA and ALARMC lines are of particular interest because the base station has optional external fault monitoring capabilities. For ~\Technical Documentation\System Manuals\FCC-Reports\DR4B-FCCRpt.doc Page 6 SECTION 1: THEORY OF OPERATION example, if a fault in the base station site produces a contact closure on one of the alarm inputs, the radio transmits a fault message to the Communication Center. Examples of faults include site door open, high temperature, high VSWR, etc. Upon receipt of the fault message, a technician is dispatched to the base station site to correct the fault. In order to obtain these capabilities, monitoring software must be loaded into the System Controller Board CPU and the Internet Protocol Network Controller (IPNC). Another header (J1) routes RS232 data, clock, and handshake signals from the System Controller Board to DB25 interface connector (J3). This connector is physically mounted on the rear panel of the base station. This section displays the level shifters for the three (3) receivers. Each receiver provides a DC voltage received signal strength indication (RSSI) corresponds to the signal strength of an incoming signal. The RSSI output from receiver 1 appears at RSSI1. It passes through low pass filter R13 and C16. The low pass filter capacitor (C16) minimizes RF pickup by the op amp. An op amp (U11B) provides amplification and a DC level shift. An additional op amp (U11C) provides additional amplification. Resistors (R3 and R4) and a pot (R11) set gain of the op amp. The DC offset is injected into U11C via a pot (R12) and a resistor (R5). The amplified and level shifted output leaves the op amp as SHIFT_ RSSI1 and goes to a comparator circuit. The remaining level shifters work in the same manner. Individual gain and DC offset pots are provided so that minor RSSI performance differences between the three receivers can be trimmed out. Receive Signal Strength Indication Comparator This section displays the RSSI comparator circuitry. It uses a two-step selection process to determine which receiver has the strongest signal, as follows: The receiver 1 and receiver 2 RSSIs are compared, and the strongest receiver is selected. The selected receiver’s RSSI and receiver 3 RSSI are compared, and the strongest is selected. The circuitry provides two (2) digital outputs and an analog RSSI voltage from the selected receiver. A comparator (U5) looks at the RSSI1 and RSSI2 inputs. When RSSI1 is greater than RSSI2, the comparator output goes high, and a LED (D1) lights to indicate receiver 1 was selected. At the same time, the RX1/RX2_SELECT line goes high, which activates the solid-state switch (U8). This causes the receiver 1 RSSI signal to be routed to a second comparator. Otherwise, if the receiver 2 RSSI is greater than receiver 1, the RX1/RX2_SELECT line goes low, and another LED (D2) lights to indicate receiver 2 was selected. U8 simply routes receiver 2 RSSI to a second comparator (U10). The digital RX1/RX2_SELECT output controls a switch. U10 looks at the selected receiver (RSSI1/RSSI2) and RSSI3 inputs. Should RSSI3 be greater than the other input, the comparator output goes high, and LED (D3) lights to show receiver 3 is selected. At the same time, another switch (U6) connects RSSI3 to the analog SEL_RSSI output. The digital RX3_SELECT output controls a switch. Otherwise, if the selected receiver’s RSSI is greater than RSSI3, the comparator output remains low making the RX3_SELECT output low. U6 simply connects the selected receiver’s analog RSSI signal to the SELRSSI output. A chip (U3) forms a comparator circuit. When the RSSI voltage exceeds a threshold, a LED (D4) lights. Like the other three (3) LEDs, this circuit is intended as a diagnostic tool. It provides a go/no go indication that an RF signal has been received. A pot (R74) sets the turn-on voltage. ~\Technical Documentation\System Manuals\FCC-Reports\DR4B-FCCRpt.doc Page 7 SECTION 1: THEORY OF OPERATION Baseband This circuitry amplifies the audio from each receiver, routes it through solid-state switches, and selects the audio from the receiver with the highest quality value. The comparator circuit on the previous sheet controls it. There are three (3) channels of audio, with separate gain and DC offset adjustments to compensate for performance differences in the receivers. For example, incoming audio from receiver 1 appears at AUDIO 1. An op amp (U12D) is then amplifies the audio. A pot (R72) adjusts the gain. The amplifier output drives a switch (U4). The remaining audio circuits work in the same manner. Two (2) solid-state switches route audio from the selected receiver. U4 selects audio from either Receiver 1 or 2. When the RX1/RX2_SELECT input from the comparator circuitry is high, Receiver 1 audio is passed through the device. Another switch (U7) selects audio from either a selected Receiver (1 or 2) or receiver 3. When the RX3_SELECT input from the comparator circuitry is high, Receiver 3’s audio is passed through the device. The output from U7 appears on DISC_AUD, which goes to a header (J2). From there the audio is demodulated by the modems on the System Controller Board. The radio also offers a voice grade audio output via the rear panel DB25 connector. DISC_AUD also drives low pass filter (U14), and buffer (U9D). The AUDIO OUT line from the buffer goes to pin 12 of a connector (J3). This section displays manual receiver switching and DC power distribution. Manual receiver switching is primarily intended as a diagnostic tool. By closing various switches on S1, the RX1/RX2_SELECT or RX3_SELECT LINES may be forced high or low, as appropriate. This overrides the operation of the comparator circuitry, forcing one receiver to operate at all times. Resistors (R98 and R97) provide power supply short circuit protection in the event the wrong switches are closed. Pads (TP4 and TP5) represent the power distribution bus (TP4 and TP5). Incoming power from the rear panel fuse holder appears on pad TP4. The B+ output goes to the power supply circuitry. TP5 connects to the transmitter power amplifier. Receiver Board Please be aware that the radio uses three (3) identical receiver boards. As a result, the circuitry will be described only once. Front end. Incoming signals pass through a filter (FT1). The filter (FT1) is a double-tuned device, which provides a high degree of selectivity. The desired signals are amplified by U4, a low noise amplifier. Additional selectivity is provided by triple-tuned filter (FT2). An RF amplifier (Q1) amplifies the signal. The output from Q1 passes through triple-tuned filter (FT3), and then to mixer (U5). U5 is a doublebalanced mixer, which heterodynes a local oscillator signal from the Injection Synthesizer Board. The IF output leaves the mixer as the 45 MHz line. It goes to an IF filter on the following sheet. There are five (5) filter sets (FT1, FT2, and FT3) available, and each covers a 20-30 MHz portion of the UHF band. Should replacement of the filters be required, exact replacement parts must be used. ~\Technical Documentation\System Manuals\FCC-Reports\DR4B-FCCRpt.doc Page 8 SECTION 1: THEORY OF OPERATION IF Amplifier The incoming 45 MHz signal passes through Y5, a highly selective monolithic bandpass filter. From there the IF signal passes through an LC matching network. C17, C18, C24, and L5 provide impedance matching to the IF amplifier input. U6 is a super heterodyne IF subsystem. Inside the chip, the signal is applied to a mixer. The mixer also accepts a 44.545 MHz local oscillator input. The local oscillator consists of an internal amplifier, plus crystal (Y4) and associated components. The mixer output passes through Y3, a 455 KHz ceramic IF filter. It is amplified, passed through ceramic filter (Y2), and on to a second IF stage. The IF output drives a quadrature detector. The recovered audio appears at pin 9, while RSSI appears at pin 7. Within the RSSI circuitry, chip U6 uses a detector, which converts if the current is generated inside the chip into a DC level corresponding logarithmically to signal strength. RSSI is used by the Diversity Reception Controller to select the receiver with the highest quality signal. The audio is buffered by op amp U3A. From there the AUDIO output line goes to a connector, for hookup to the Diversity Reception Controller Board. The RSSI is buffered by op amp U3B. From there the RSSI output line goes to a connector, for hookup to the Diversity Reception Controller Board. Several sets of 455 KHz IF filters (Y3 and Y2) are available to suit receiver selectivity requirements. Should replacement of these filters be required, exact replacement parts must be used. Receiver Injection The Injection Synthesizer Board provides a highly stable local oscillator signal for the three receivers. A synthesizer on the board develops the signal. This displays a serial data input/output interface, synthesizer, and VCO. The I/O interface circuitry accepts clock, serial data, and enable signals from the System Controller Board via terminal block TB1. A lock detect (LD) status output is returned to the System Controller Board from the synthesizer. U3 is a hex Schmidt Trigger inverter, which squares up incoming signals for reliable operation of the synthesizer chip. This is necessary because of a cable run between the two (2) boards. The main section of this board is synthesizer chip (U2). The device contains the key components of a phase locked loop (PLL), including a 1.1 GHz prescaler, programmable divider, and phase detector. In operation, the desired frequency is loaded into U2 as a clocked serial bit stream via the CLK and DATA/I inputs. The lock detection circuitry consists of inverters U3E/U3F, diode CR3, and resistor R5. When the synthesizer is in lock, the LD pin on U2 is high, making the LD output on terminal block TB1 high. The EXC LD input on TB1 routes the lock detect output from the Exciter Board through diode CR3, and out through LD. This configuration tells the CPU on the System Controller Board that it is acceptable to process received data, or to key the transmitter when LD is high. Otherwise, if a fault in either synthesizer prevents a lock, receive and transmit operation will be inhibited. The UHF injection signal is generated by module VCO1. This device is a wide-range voltage controlled oscillator (VCO). A voltage on the VT input determines the VCO frequency. The voltage is generated by the phase detector output (PD/O) of U2, which drives a loop filter consisting of R4, C19, C20, R21 and C10. The filter integrates the pulses, which normally appear on PD/O into a smooth DC control signal for the VCO. The output of VCO1 is attenuated by module AT1, resulting in improved VCO stability. ~\Technical Documentation\System Manuals\FCC-Reports\DR4B-FCCRpt.doc Page 9 SECTION 1: THEORY OF OPERATION This section displays the DC power supplies, frequency reference, and RF output circuitry. Regulator VR1 provides 9 volts DC for VCO module VCO1, and RF amplifier (U7). Regulator (VR2) provides a low noise 5-volt DC output for inverter (U3), synthesizer (U2), and reference (Y1). Reference module (Y1) provides a high-stability 10 MHz reference frequency. Y1 is a voltage controlled, temperature controlled crystal oscillator (VCTCXO). This device also has a VC input which accepts a control voltage from pot R23. The pot permits a slight shift in the reference frequency which enables the three (3) receivers to be tuned precisely to the assigned receive frequency. A diode (CR2) provides additional voltage regulation, improving the frequency stability of reference Y1. The RF output circuitry consists of RF amplifier (U7), and power splitters (U5 and U6). U7 increases the signal level to correct for losses in the splitters. One output drives splitter U5, which provides local oscillator injection for Receivers 2 and 3. The other output drives splitter (U6), which drives receiver 1 and the PLL_FEEDBACK input on chip U2. Exciter Board This section displays the input/output interface, transmitter keying, and power supply circuitry. The input/output interface is built around terminal block (TB1) and Schmidt Trigger inverters (U7). Incoming clock, serial data, and chip select signals on block TB1 are squared up by U7. Then they are sent to the appropriate inputs on the transmitter synthesizer (U2). The EXCDATA source comes from the receive synthesizer on the Injection Synthesizer Board. A Schmidt Trigger chip is used here because of a cable ran to the System Controller Board. The synthesizer returns a lock detect output to the Injection Synthesizer Board via U6 and EXCLD. A regulator (VR2) powers the T/R switch circuitry. When the System Controller Board makes TXKEY* low, inverter U6D goes high, turning on transistor Q2 and FET Q1. This applies 5-volt power to the TXENABLE output, turning on the T/R switch on the Power Amplifier Board. At the same time, transistor Q3 conducts, grounding the KEY* input of the Power Amplifier Board. Finally, inverter U6C goes high and turns on RF switch U1, connecting the VCO output to the Power Amplifier Board for transmission. The power supply consists of two (2) voltage regulators. A regulator (VR1) provides 5-volt power for the VCO. Analog Modulation This section displays the analog modulation circuitry. Incoming modem audio from the System Controller Board appears at TXMOD, and is buffered by op amp U5C. If an external modulation source (modem or amplified microphone) is connected to the base station’s DB25 connector, audio appears at EXTMOD. From there the audio passes through low pass filters U10, U4DCBA, and on to the input of op amp U5B. The audio is inverted and amplified by an op amp (U5B). It then passes on to the VCO module via VCOMOD. The 10 MHz reference is also modulated in order to counteract the corrective effects of the synthesizer loop circuitry. For example, if only the VCO were modulated, the synthesizer would try to compensate for the frequency “error,” caused by the modulation. This effectively reduces the amount of modulation available. Modulating the reference and the VCO simultaneously effectively cancels this effect when the reference frequency goes high, the VCO frequency goes high, and vice-versa. An op amp (U9A) amplifies the AUDIO output from another op amp (U5D) and applies it to jumper block JMP1. Pot R30 adjusts the gain of U9A. Op amp (U9B) inverts the phase of the audio and applies it to the other side of jumper block JMP1. The purpose of the jumper block is to select the proper phase of the audio. If the wrong phase is used, on modulation peaks the reference will swing in the same direction as ~\Technical Documentation\System Manuals\FCC-Reports\DR4B-FCCRpt.doc Page 10 SECTION 1: THEORY OF OPERATION the VCO, canceling out most of the modulation. The output from the jumper block goes to the 10 MHz reference via REFMOD. The VBIAS input is a 2.5-volt DC source, which biases the op amps to the correct operating point. It is generated by modem chip (U14) on the System Controller Board. Phase Locked Loop This section displays phase locked loop (PLL) circuitry. The 10-MHz reference (Y1), runs synthesizer (U2), which in turn controls VCO1. The main section of this board is the synthesizer chip (U2). The device contains the key components of a PLL, including a 1.1 GHz prescaler, programmable divider, and phase detector. In operation, the desired frequency is loaded into U2 as a clocked serial bit stream via the CLK and DATA/I inputs. The lock detection circuitry consists of inverters U6A and U6B, diode CR1, and resistor R1. When the synthesizer is in lock, the LD pin on U2 is high, making the EXCLD output on terminal block (TB1) high. The EXCLD output on TB1 routes the lock detect output from the Exciter Board. This configuration tells the CPU on the System Controller Board that it is acceptable to process received data, or to key the transmitter when LD is high. Otherwise, if a fault in either synthesizer prevents a lock, receive and transmit operation will be inhibited. The switch (JMP1) is used to select the supply voltage to chip U2. The UHF injection signal is generated by module VCO1. This device is a wide-range voltage controlled oscillator (VCO). A voltage on the VT input determines the VCO frequency. The voltage is generated by the phase detector output (PD/O) of U2, which drives a loop filter consisting of R19, C16, C17, and C47. The filter integrates the pulses, which normally appear on PD/O into a smooth DC control signal for the VCO. The output of VCO1 is attenuated by module AT2, resulting in improved VCO stability. Amplifier U8 amplifies the signal and applies it to a splitter (U3). One output of U3 is connected to a switch (U1). U1 is enabled by signal TX when the transmitter is enabled. The other output of the splitter is connected through AT1 and provides feedback to U2. Power Amplifier The transmit injection signal from the RF injection section is applied to the high-powered linear amplifier (U1) one (1) watt amplifier. The signal is then routed to the final power amplifier boosting the output signal to 40 watts. The output of the amplifier is routed to transmit antenna port ANT1 (via SW1). ~\Technical Documentation\System Manuals\FCC-Reports\DR4B-FCCRpt.doc Page 11 SECTION 2: FACTORY TEST PROCEDURE Equipment List The following table lists the equipment required to perform the DT450 Mobile Data Radio Factory Test Procedure: QTY DESCRIPTION MANUFACTURER PC’s One for Mobile One for Base Service Monitor – Communication Test Set Windows 9X w/ IPMessage AVR Digital multi-meter DC power supply w/ ammeter, 13.8V, 12 Amps or more 4-Channel Scope DR4B Calibrated Base Station Internet Protocol Network Controller (IPNC) 100 watt dummy load/attenuator UHF Antennas (generic mag mount) Serial cable DB25M-DB25F connectors DT power cable 3-foot RF jumper cable with type N connectors (generic) Scope test probe (generic, X1 attenuation) Ceramic tuning tool 1 ea MODEL HP HP890 or equivalent Tektronix Fluke 77 or equivalent Astron VS12M or equivalent Tektronix TDS 460A Pasternack PE7021-40 or equivalent IPMN p/n: 44010006 #0, #1, and #2 Phillips screwdrivers (generic) ~\Technical Documentation\System Manuals\FCC-Reports\DR4B-FCCRpt.doc Page 12 SECTION 2: FACTORY TEST PROCEDURE Programming and Configuring the Base Station Data Radio Once the appropriate equipment for performing the factory test are gathered, perform the following steps to rpgoram and configure the DR4B Base Station Data Radio: Step 1 Enter the following information on the Base Station Data Radio Performance Test Data Sheet: Base Station Serial number Date test being performed Tester’s name Step 2 At the HyperTerminal window, type in the appropriate password and press [ENTER]. Step 3 Type ? and press [ENTER]. The following example displays in the HyperTerminal window: Host serial = 115200,N,8,1, timeout=200 Host framing = SLIP, no split frames no status messages tunnel = 0 TX format = new Injection = LOW SIDE, 45MHz channel spacing = 25000 Channel = 0 Channel Tx freq Rx freq Inj freq Frequency=0 , 481.000000, 486.000000, 441.000000 Serial number: yyyyyyyyy RIM address = 1 Frequency group = 1 TX quiet time = 5 Symbol sync time = 12 milliseconds, 0 extra inter-split-frame count TX tail time = 5 Radio data rate = 19200 Max data tx time = 60 seconds Carrier detect delay time = 1 millisecond Station ID = ABC123 Station ID time =10 minutes Polarity = TX+, RX+ Allow crc errors = 0 Suppress keep alive = 0 Allow base to base = 0 Timeslot status = 0 Duplicate time = 10 milliseconds Control head grant delay = 50 milliseconds RIM DD delay = 0 milliseconds Retry interval = 0 milliseconds Retry time limit = 0 milliseconds RSSI step = 25 (=19dBm) IPNC = 192.168.3.3 SLIP Address = 192.168.4.6 RF IP Address = 192.168.3.1 SNTP interval = 60 seconds num timeslots = 16 timeslot period = 992ms timeslots per voice packet = 4 noise = -128dBm Fixed TX Delay = 0 milliseconds Scale TX Delay = 0 microseconds ~\Technical Documentation\System Manuals\FCC-Reports\DR4B-FCCRpt.doc Page 13 SECTION 2: FACTORY TEST PROCEDURE Adjustment / Alignment Procedures Receiver Injection Perform the following steps to adjust the receiver injection and injection frequency: Step 1 Using the HP high frequency probe, verify that the receiver injection frequency is present at each of the three (3) receivers by monitoring the receivers’ R12 surface mount pad which lies on the 50 ohm track between L3 and U3.6. Step 2 Adjust R7 on the receiver injection circuit board to set the injection frequency within 10 Hz of the exact injection frequency. The amplitude of the injection frequency should read approximately +5 dBm ±1 dBm. Receiver 1 Step 1 Using the high frequency probe, monitor the 44.545 MHz second injection frequency at U2 pin 3, adjust trimmer capacitor (C5) to the center of the oscillator’s oscillation range. The amplitude level of pin 3 of U2 should read between +5 and +10 dBm. Step 2 Inject an on-frequency signal at a level of –80 dBm, modulated with a 1 KHz test tone at ±5.0 KHz deviation into the receiver under test. Step 4 While monitoring RSSI at TB1-4 with the digital multi-meter, adjust the trimmer capacitor (C1) for maximum RSSI. The RSSI properly tuned receiver should be approximately 2.8 to 3.4 VDC. Step 5 Check the receiver’s distortion and verify that it is less than 3%. Step 6 Adjust C1 slightly if necessary for minimum distortion. Step 7 Check the receiver’s sensitivity, verifying that the SINAD is 12 dB or better at a maximum level of –119 dBm (-120 is typical). Step 8 Repeat procedure for Receivers 2 and 3. Diversity Reception Controller Step 1 Inject an on-frequency signal at a level equal to Receiver 1 12dB SINAD level, modulated with a 1 KHz test tone at ±5.0 KHz deviation into Receiver 1. Step 2 While monitoring TP1 with the digital multi-meter, adjust RSSI1 low adjust potentiometer (R12) for a reading of 0.750 VDC ±10 mV. Step 3 Increase the amplitude of the signal by 50 dBm. Step 4 While monitoring TP1 with the digital multi-meter, adjust RSSI1 high adjust potentiometer (R11) for a reading of 2.75 VDC ±10 mV. Adjustments R11 and R12 are interactive adjustments, therefore continue adjustments until the DC voltage at TP1 is 0.750 VDC for the receiver’s 12 dB SINAD level and 2.75 VDC for a 50 dBm increase from the receiver’s 12 dB SINAD level. ~\Technical Documentation\System Manuals\FCC-Reports\DR4B-FCCRpt.doc Page 14 SECTION 2: FACTORY TEST PROCEDURE Step 5 Inject an on-frequency signal at a level equal to Receiver 2 12dB SINAD level, modulated with a 1 KHz test tone at ±5.0 KHz deviation into Receiver 2. Step 6 While monitoring TP2 with the digital multi-meter, adjust RSSI2 low adjust potentiometer (R10) for a reading of 0.750 VDC ±10 mV. Step 7 Increase the amplitude of the signal by 50 dBm. Step 8 While monitoring TP2 with the digital multi-meter, adjust RSSI2 high adjust potentiometer (R9) for a reading of 2.75 VDC ±10 mV. Adjustments R9 and R10 are interactive adjustments, therefore continue adjustments until the DC voltage at TP2 is 0.750 VDC for the receiver’s 12 dB SINAD level and 2.75 VDC for a 50 dBm increase from the receiver’s 12 dB SINAD level. Step 9 Inject an on-frequency signal at a level equal to Receiver 3 12dB SINAD level, modulated with a 1 KHz test tone at ±5.0 KHz deviation into Receiver 3. Step 10 While monitoring TP3 with the digital multi-meter, adjust RSSI3 low adjust potentiometer (R33) for a reading of 0.750 VDC ±10 mV. Step 11 Increase the amplitude of the signal by 50 dBm. Step 12 While monitoring TP3 with the digital multi-meter, adjust RSSI3 high adjust potentiometer (R35) for a reading of 2.75 VDC ±10 mV. Adjustments R33 and R35 are interactive adjustments, therefore continue adjustments until the DC voltage at TP3 is 0.750 VDC for the receiver’s 12 dB SINAD level and 2.75 VDC for a 50 dBm increase from the receiver’s 12 dB SINAD level. Step 13 Adjust the carrier detect potentiometer (R74) to illuminate a level of –116 dBm. Receive Data Step 1 Using a calibrated mobile radio, generate uplink data messages using the X=2000,19 command in the IP Message Utility program (see the Internet Protocol (IP) Data Transceiver IP4/IP8 System Manual for instructions). Step 2 Attach an antenna to one of the base station’s receiver ports and verify on the base station monitor screen (HyperTerminal) that the received message data quality are consistently 240 and higher for 2000 character messages. Repeat test for each receiver. Constant fluctuations in the data quality are indicative of group delay programs. The data quality readings should always be at or above 240. ~\Technical Documentation\System Manuals\FCC-Reports\DR4B-FCCRpt.doc Page 15 SECTION 2: FACTORY TEST PROCEDURE Exciter Step 1 Using the X=2000,19 command, generate data messages so the transmit power and frequency can be checked. Step 2 Connect the base stations' transmit port to the HP communication test set. Note the power level prior to adjusting. Step 3 On the power amplifier circuit board adjust the potentiometer (RV1) fully clockwise (this will enable low power transmit operation). Step 4 While transmitting data messages using the X=2000,19 command, adjust the following: TCXO Y1 and R14 for minimum frequency error R11 for ±5.0 KHz deviation Transmit output power should be approximately 1mWatt. The REFMOD adjustment needs to be made while the base station is transmitting real data messages to and from a mobile radio. This is most easily done using the ping command to ping the IPNC from a mobile radio. This will cause the base station to repeatedly send data messages and will facilitate the REFMOD adjustment. Step 5 Connect the base station to the IPNC. Step 6 Using a calibrated mobile radio operating on the base station’s channel, adjust R4 for consistent data quality readings of 248 (as observed on the mobile radio’s attached PC IP Message window). Access the MSDOS prompt and ping using the following command: >;ping 192.168.3.3 –t -l 500 –w 2000 This command will ping the IPNC continuously with a 500-character test message. Press [Ctrl]+C to stop the ping. Power Amplifier Step 1 Connect the base stations' transmit port to the communication test set. Step 2 Using the X=2000,19 command, generate data messages. Step 3 Slowly increase the base station output power by turning the power control potentiometer counterclockwise until the power noted previously or 40 Watts of output power is obtained or to the level. Step 4 Do not exceed 20 watts output power as this will reduce the life of the amplifier module. Perform a close visual inspection of the radio paying close attention to manufacturing related problems such as loose screws, solder practices, etc. ~\Technical Documentation\System Manuals\FCC-Reports\DR4B-FCCRpt.doc Page 16 SECTION 3: FCC LABEL DR4B Base Station Data Radio FCC Label Placement DR4B Base Station Data Radio FCC Label Placement ~\Technical Documentation\System Manuals\FCC-Reports\DR4B-FCCRpt.doc Page 17 APPENDIX B: DR4B CIRCUIT BOARD DIAGRAM ~\Technical Documentation\System Manuals\FCC-Reports\DR4B-FCCRpt.doc Page 18
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