3-10
Theory of Operation:
Main Board
The output of the discrete image filter is applied to the RF port of the Mixer IC (U507) via a balun
transformer (T506). The Mixer IC is driven by a Local Oscillator (LO) signal at the LO port to down-
convert the RF signal to a 109.65 MHz intermediate frequency (IF). The down converted IF signal is
passed through a crystal filter (FL502) which drives the input of the Abacus 3 Analog to Digital
Converter IC (AD9864)(U601).
3.1.2.4 Analog To Digital Converter
The ADC IC's front end down converts the first IF to a second IF, a 2.25 MHz signal, by mixing a
107.4MHz LO signal generated by an integrated synthesizer and external VCO with active device
U602 and resonator L604. The second IF is sampled at 18 MHz, a signal generated by an integrated
clock synthesizer and VCO device with external resonator L605.
The sampled signal is decimated by a factor of 900 to 20 kHz and converted to SSI format at the
ADC's output. The Serial Synchronous Interface (SSI) serial data waveform is composed of a 16 bit
in-phase word (I) followed by a 16 bit Quadrature word (Q). A 20 kHz Frame Synch and a 1.2 MHz
clock waveform are used to synchronize the SSI IQ data transfer to the Digital Signal Processor IC
(OMAP) for post-processing and demodulation.
3.1.3
Transmitter
The transmitter takes modulated RF from the FGU and amplifies it to the rated output power to
produce the modulated carrier at the antenna.
NOTE:
Refer to
Table 8-1
for a listing of transmitter-related schematics that will aid in the following
discussion.
The transmitter (
Figure 3-1
) for the UHF1 radio consists of one MOSFET high power transistor for
the UHF1 band. The same topology applied for the
700/800 MHz radio (
Figure 3-3
) where one MOSFET high power transistor is used for the 700/800
MHz band. The high power transistor is driven by an RF driver IC that receives its input signal from
the voltage controlled oscillator. Transmitter current is controlled by a discrete current
control circuit that senses the current drawn by the Power Amplifier and the driver IC via a sensing
resistor which controls the Power Amplifier and driver IC control voltage to maintain the overall
current level. The TX signals pass through the antenna switch that will provide switching mechanism
from transmit to receive path. The signal then route through each respective harmonic filters, an
embedded directional coupler and finally to the antenna.
Содержание APX 2000
Страница 1: ...APXTM TWO WAY RADIOS APX 1000 APX 2000 APX 4000 APX 4000Li DETAILED SERVICE MANUAL ...
Страница 4: ......
Страница 6: ...iv Document History Notes ...
Страница 8: ...Notes vi Commercial Warranty ...
Страница 10: ...Notes ...
Страница 22: ...xiv List of Figures Notes ...
Страница 165: ...Troubleshooting Waveforms Clocks 6 3 6 2 2 4 MHz Clock Trace 1 Trace recorded at R6113 Figure 6 2 4 MHz Clock Waveform ...
Страница 172: ...6 10 Troubleshooting Waveforms Audio SSI 6 3 4 BCLK Trace 1 Trace recorded at R6107 Figure 6 9 Audio SSI BCLK Waveform ...
Страница 174: ...6 12 Troubleshooting Waveforms RX SSI 6 4 2 DA Trace 1 Trace recorded at R2805 Figure 6 11 RX SSI DA Waveform ...
Страница 175: ...Troubleshooting Waveforms RX SSI 6 13 6 4 3 FSYNC Trace 1 Trace recorded at R2804 Figure 6 12 RX SSI FSync Waveform ...
Страница 177: ...Troubleshooting Waveforms TX SSI 6 15 6 5 2 DA Trace 1 Trace recorded at R2817 Figure 6 14 TX SSI DA Waveform ...
Страница 178: ...6 16 Troubleshooting Waveforms TX SSI 6 5 3 FSYNC Trace 1 Trace recorded at R2807 Figure 6 15 TX SSI FSync Waveform ...
Страница 179: ...Troubleshooting Waveforms SPI 6 17 6 6 SPI 6 6 1 CLK Trace 1 Trace recorded at R2803 Figure 6 16 SPI CLK Waveform ...
Страница 180: ...6 18 Troubleshooting Waveforms SPI 6 6 2 CS Trace 1 Trace recorded at R6602 Figure 6 17 CS Waveform ...
Страница 182: ...6 20 Troubleshooting Waveforms I2C BUS 6 7 2 SCL 5V Trace 1 Trace recorded at R2204 Figure 6 19 I2C Bus SCA 5V Waveform ...
Страница 183: ...Troubleshooting Waveforms I2C BUS 6 21 6 7 3 SDA Trace 1 Trace recorded at R6209 Figure 6 20 I2C Bus SDA Waveform ...
Страница 187: ...Troubleshooting Waveforms USB 6 25 6 10 USB 6 10 1 D Trace 1 Trace recorded at TP F_GCAI_USB Figure 6 24 USB D Waveform ...
Страница 188: ...6 26 Troubleshooting Waveforms USB 6 10 2 D Trace 1 Trace recorded at TP F_GCAI_USB Figure 6 25 USB D Waveform ...
Страница 190: ...6 28 Troubleshooting Waveforms SDRAM 6 11 2 CLKX Trace 1 Trace recorded at TP6308 Figure 6 27 SDRAM CLKX Waveform ...
Страница 226: ...6 64 Troubleshooting Waveforms LF CW on Spectrum Analyzer Notes ...
Страница 284: ...8 4 Schematics Boards Overlays and Parts Lists List of Transceiver Schematics and Board Overlays Notes ...
Страница 688: ...Index 4 Index Notes ...
Страница 689: ...Title Page ASTRO APX 1000 Digital Portable Radios Section 2 VHF UHF1 UHF2 700 800 MHz APX 1000 ...
Страница 690: ...ii Notes ...
Страница 695: ...List of Tables xi Related Publications APX 1000 Digital Portable Radios Basic Service Manual 68012004056 ...
Страница 700: ...xvi List of Figures Notes ...
Страница 756: ...4 6 Troubleshooting Procedures Power Up Self Check Diagnostics and Repair Not for Field Use Notes ...
Страница 806: ...5 50 Troubleshooting Charts PA Failure Notes ...
Страница 809: ...Troubleshooting Waveforms Clocks 6 3 6 2 2 4 MHz Clock Trace 1 Trace recorded at R6113 Figure 6 2 4 MHz Clock Waveform ...
Страница 816: ...6 10 Troubleshooting Waveforms Audio SSI 6 3 4 BCLK Trace 1 Trace recorded at R6107 Figure 6 9 Audio SSI BCLK Waveform ...
Страница 818: ...6 12 Troubleshooting Waveforms RX SSI 6 4 2 DA Trace 1 Trace recorded at R2805 Figure 6 11 RX SSI DA Waveform ...
Страница 819: ...Troubleshooting Waveforms RX SSI 6 13 6 4 3 FSYNC Trace 1 Trace recorded at R2804 Figure 6 12 RX SSI FSync Waveform ...
Страница 821: ...Troubleshooting Waveforms TX SSI 6 15 6 5 2 DA Trace 1 Trace recorded at R2817 Figure 6 14 TX SSI DA Waveform ...
Страница 822: ...6 16 Troubleshooting Waveforms TX SSI 6 5 3 FSYNC Trace 1 Trace recorded at R2807 Figure 6 15 TX SSI FSync Waveform ...
Страница 823: ...Troubleshooting Waveforms SPI 6 17 6 6 SPI 6 6 1 CLK Trace 1 Trace recorded at R2803 Figure 6 16 SPI CLK Waveform ...
Страница 824: ...6 18 Troubleshooting Waveforms SPI 6 6 2 CS Trace 1 Trace recorded at R6602 Figure 6 17 CS Waveform ...
Страница 826: ...6 20 Troubleshooting Waveforms I2C BUS 6 7 2 SCL 5V Trace 1 Trace recorded at R2204 Figure 6 19 I2C Bus SCA 5V Waveform ...
Страница 827: ...Troubleshooting Waveforms I2C BUS 6 21 6 7 3 SDA Trace 1 Trace recorded at R6209 Figure 6 20 I2C Bus SDA Waveform ...
Страница 831: ...Troubleshooting Waveforms USB 6 25 6 10 USB 6 10 1 D Trace 1 Trace recorded at TP F_GCAI_USB Figure 6 24 USB D Waveform ...
Страница 832: ...6 26 Troubleshooting Waveforms USB 6 10 2 D Trace 1 Trace recorded at TP F_GCAI_USB Figure 6 25 USB D Waveform ...
Страница 834: ...6 28 Troubleshooting Waveforms SDRAM 6 11 2 CLKX Trace 1 Trace recorded at TP6308 Figure 6 27 SDRAM CLKX Waveform ...
Страница 1008: ...8 178 Schematics Boards Overlays and Parts Lists Transceiver RF Boards UHF2 84012621001 Notes ...
Страница 1062: ...8 234 Schematics Boards Overlays and Parts Lists Keypad Board M2 and M3 PC000261A01 Notes ...
Страница 1063: ...Title Page ASTRO APX 1000 APX 2000 APX 4000 APX 4000 Li Digital Portable Radios Section 3 Appendices ...
Страница 1064: ...ii Notes ...
Страница 1068: ...Notes A 4 EMEA Warranty Service and Technical Support Further Assistance From Motorola ...
Страница 1072: ...B 4 LACR Replacement Parts Ordering and Motorola Service Centers Motorola Service Centers Notes ...
Страница 1090: ...Glossary 10 Glossary Notes ...
Страница 1094: ...Index 4 Index Notes ...
Страница 1095: ......