UHF1(400-470MHz)
Circuit Description
22
Receiver Back-end
The first IF signal (58.05 MHz) output by the IF amplifier goes into AD9864 (U6001) via Pin 47, where
the signal is converted to the second IF signal (2.25 MHz). Then the second IF signal is converted to
digital signal via ADC sampling, and output via the SSI interface. Finally, the digital signal is sent to the
DSP (OMAP5912) for demodulation.
AD9864 employs reference frequency of 19.2 MHz and shares the crystal with OMAP. The second LO
VCO comprises an oscillator, a varactor and some other components, to generate the LO signal
(55.8/60.3 MHz). The 18MHz clock frequency is generated by the LC resonance loop.
5.2.3
FGU
The FGU is composed of VCO and PLL. It is the core module of the whole TX-RX system. This circuit
provides accurate carrier frequency during transmission, and stable LO signal during reception. It plays
a pivotal role and determines the performance of the system.
Summary of Contents for PD502
Page 1: ...PORTABLE...
Page 5: ...VHF 136 174 MHz...
Page 13: ...VHF 136 174 MHz Exploded View and Packaging Guide 7 3 2 Packaging Guide...
Page 18: ...VHF 136 174 MHz Circuit Description 12...
Page 43: ...PCB 3 9 PCB VHF 136 174 MHz...
Page 44: ...PCB 3 VHF 136 174 MHz...
Page 71: ...UHF1 400 470 MHz...
Page 79: ...UHF1 400 470MHz Exploded View and Packaging Guide 7 3 2 Packaging Guide...
Page 84: ...UHF1 400 470MHz Circuit Description 12...
Page 108: ...UHF1 400 470MHz PCB 36 9 PCB...
Page 109: ...UHF1 400 470MHz PCB 37...
Page 136: ...1616300000260 2014 03 17 L07157 4...
