A-510T(UHF)Ver1.0
18/53
VCO
LDO
0/90
SQL
VOX
CLK
SDIO
PDN
SC
CT/DCSS DECODE
Synthesizer
LNA
Q
ADC
Q
PGA
I
ADC
I
PGA
DSP
Core
Audio filter
Sub CH filter
FM modem
AFC loop
RSSI
ADC
DAC
GPIO
Interface
Bus
3V3
3V3
RFOUT
PA_drvier
RFIN
APC_SW
CTC MOD
12. 8MHZ
MIC
AFOUT
Chart 4 RD1846S
(
1
)
Phase lock
The step frequency of phase lock is 5 or 6.25 KHz. 12.8MHz reference oscillator signal is scaled down by
phase-locked loop U9 and generates 5 or 6.25 KHz of reference frequency by a mixed counter.
(
2
)
Noise suppression
Use U9 to detect whether the noise is above or below the default, and produce high/low level to enter the SOL
port of microprocessor U300. microprocessor U300 can decide whether the speaker outputs voice by detecting the
input high/low level(to output the voice, the microprocessor U300 sends a high level signal to FM MUTE control wire
by Q302 and enable the audio power amplifier U306.
(
3
)
QT/DQT code
The received carrier frequency is demodulated to be audio signal by U302
,
and that audio signal is filtered by
filter to remove the unwanted signal, then the signal is changed into plus signal by U302 analog-digital converter, then
the plus signal enter the microprocessor U300
(
CTC/CDCSS DECODE). The microprocessor U300 can determine
whether QT or DQT matches the value set, and according with the result of noise suppression circuit control the FM
MUTE and speaker to output voice.
(
4
)
Audio amplifier
The audio signal demodulated by U302, through VR1 volume control circuit, then through the amplification of
audio power amplifier U306, can drive the speaker.
(
5
)
Audio transmission
The voice signal is produced by internal microphone (M1) or external microphone, and the signal is conducted
Содержание A-510T
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Страница 14: ...A 510T UHF Ver1 0 14 53 4 5 Exploration Chart of Parts ...
Страница 48: ...A 510T UHF Ver1 0 48 53 Diagram 1 A 510T Tag Number Diagram TOP ...
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Страница 53: ...A 510T UHF Ver1 0 53 53 Diagram 4 A 510T Packaging ...