Receiver Circuit; Receiver Front-End; Figure 6-2 Diagram Of Receiver Circuit - RCA RDR9000 Service Manual

Service Manual 6. UHF1 (400-470 MHz) Information

6.2 Receiver Circuit

The receiver circuit is mainly composed of RF band-pass filter, low-noise amplifier, mixer, IF
filter, IF amplifier, and IF processor.
FLO Amp
Low-Pass Filter
Q6001
FLo
Antenna
TX
IF RF
IF Amp IF Filter Band-Pass Filter
Band-Pass Filter Low-Noise Amp
TX/RX Switch Low-Pass Filter
U6001
D6002
Q6002
Mixer
Pi Attenuator
Q6003,Q6004
TV/APC
IF Processor
AD9864
U6002
To DSP (OMAP)
-16 dB Decimation
ADC
Attenuation Filter
Synthesizer
Second
19.2 MHz
Lo VCO
Reference Clock

Figure 6-2 Diagram of Receiver Circuit

6.2.1 Receiver Front-End

The HF signal from the low-pass filter passes through the first-level band-pass filter, to
remove out-of-band interference signal and to send wanted band-pass signal to the low-noise
amplifier (Q6002). The amplified signal goes to the second-level band-pass filter, to remove
out-of-band interference signal generated during amplification, and to send wanted HF signal
to the mixer (D6002). In the mixer, the wanted signal and the first LO signal are mixed to
generate the first IF signal (73.35 MHz). Then the signal passes through a π-shaped
attenuator and the LC, to suppress carrier other than the first IF signal, and to increase the
isolation between the mixer and the IF filter. After that, the first IF signal is processed by the
crystal filter (U6001), and is sent to the two-stage IF amplifier circuit (composed of Q6003 and
Q6004) for amplification. Then the amplified signal goes to the IF processor AD9864 (U6002)
for processing.
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