Hytera PD362, Service Manual

Page: 95 / 141

Circuit Description
Uc (430
‐
470 MHz)
20
Receiver Back-end
The processed first IF signal is sent to IC BA4116 for second mixing (the second harmonic of the PLL
crystal will be selected as the second LO signal, which will be mixed and converted to the 450 kHz
second IF signal) and will go through the 450 kHz ceramic filter to filter out the spurious signal before the
second IF signal is amplified and frequency discriminated. Then the first IF signal will be processed
internally and demodulated. Finally, the demodulated signals will be sent to the baseband section for
audio processing.
5.2.3
Frequency Generation Unit (FGU)
The FGU , composed of VCO and PLL , is the core module of the whole TX-RX system. This unit
provides accurate carrier frequency during transmission , and stable LO signal during receipt . It has a
direct influence on the performance of the system.