Motorola MTR2000 Manual page 117

STATION CONTROL MODULE
MODEL TCN6273N
68P81094E31-I
Schematics (Sheet 18 of 36)
7/28/2007
SERVICE NOTES -AUDIO PROCESSING
Signal
Description/Nominal Signal Levels
Path
VCO MOD. Transmit audio out to exciter.
A
REF MOD. Transmit audio to modulate synthesizer reference signal. Same audio as VCO MOD but at a different level.
B
RSSI. R-2R ladder, D/A converter. Converts 7-bit RSSI output of Outlaw Glue ASIC to a 0-5V voltage.
C
Limiter. Limits the input to CODEC #2.
D
There is no Re audio path that can be monitored unless the Discriminator Rx Audio output is enabled. Rx audio comes in digitally
E
from the Abacus chip and immediately enters the DSP processor (U4400/56002).
EEPOT. Potentiometer adjusted over the SPI bus by the host processor.
F
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SCHEMATIC IC'S TABLE AUDIO PROCESSING
Reference Type
U4501 MC74AC74 Dual D-type Positive-Edge triggered Flip-Flop
U4502... CSP1027 Linear Codec
U4503... MC33074 Quad, High Performance Single Supply Op Amp
U4504... MC145480 PCM Codec
U4506... MC33074 Quad Opamp, Single Supply
U4507 MC74HC4052 Dual 4-Channel Analog Multiplexer/Demultiplexer
U4508... DS1267-10 Dual Digital Potentiometer
U4509 MC33204 Rail to Rail Op amps
U4511... MC74HC4053 Triple 2-Channel Analog Multiplexer/Demultiplexer
U4519... MC33202 Dual Rail to Rail
Description
Op Amp