A-510T(UHF)Ver1.0
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Chapter 5 Unit circuit introduction
5.1
DMR digital circuit Signal block diagram
4FSK digital signal channel process of Block diagram of DMR digital circuit:
(
1
)
Via MIC, voice comes into NJM2904V, being amplified; After that DSP digital signal is processed to 4FSK
digital modulating signal, which are sent to VCO and crystal modulator by two ways as MDO1/MOD2, then sent out
by transition circuit.
(
2
)
The 4FSK digital modulation signal received by acceptor circuit is sent to SCT3258TD DSP digital signal
processing; and it was demodulated by AMBE3000 to be 4FSK digital audio signal; then TDA2822 power amplifier
will magnify and drive SP speaker.
5.1
Circuit structure
The two way radio consists of microprocessor control circuit, receiving circuit, transmission circuit, carrier
frequency/baseband processing circuit, audio power amplifier circuit, battery/power circuit.
Radio-frequency carrier signal is directly produced by radio frequency/baseband processing chip; chopped wave
frequency in band and the principle block diagram of whole machine can be set by writing frequency software on
PC. (Refer to figure 1)
BAP65-03
Q6
RF AMP
ANT
U307
TDA2822
SP
SCT3258TD
IP data port
MIC
U306
NJM2904
Q4
TX AMP
Q3
PA AMP
DMR Circuit Structure
U302
data/vocie port
AMBE-3000
Encoder/Decoder
AD/DA switch
Frame Encoding
Frame Decoding
Modulation
Frame Header/Vaild Date
Demodulation
TDMA
12.8M
MOD2
D1 D3
X2
Voice
VCO
0/90
Q
ADC
Q
PGA
PA_drvier
MOD1
IF-IN
TLV320AIC3204
CODEC DEMOD
VCO
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