Service Manual 8. VHF (136-174 MHz) Information
235
8.2.2 Receiver Back-End
19.2 MHz
Reference
Frequency
IF Input
SSI TO OMAP
Figure 8-3 Diagram of IF Processor
The first IF signal (44.85 MHz) output by the IF amplifier goes into AD9864 (U6002) via pin 47,
where the signal is converted to the second IF signal (2.25 MHz). Then the signal is
converted to digital signal via ADC sampling, and output via the SSI interface. Finally, the
digital signal is sent to DSP (OMAP-L138) for demodulation. AD9864 employs reference
frequency of 19.2 MHz and shares the crystal with the OMAP. The second LO VCO is
composed of an oscillator, a varactor diode and some other components, to provide the
47.1/42.6 MHz LO signal. The 18 MHz clock frequency is generated by the LC resonance
loop.
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