Block Diagram For Afic - Motorola GP68 Service Manual

DET
AUDIO RX INPUT
BUFFER
Rx in
sample & holds
325 mV RMS
3rd order LP
(25khz)
Fc = 3 khz
165 mV RMS
(12.5khz)
Alert
tone in
PL/DPL
anti-aliasing
PL/DPL IN
1 pole LP
Fc = 1 khz
PL/DPL
clock
RFI
PROTECTION
EXT.
MIC
INT.
MIC
Input
7 mV to 13 mV (RMS)
nom. = 11 mV

Block Diagram for AFIC

2-12
6881086C09-O
RX AUDIO AFIC BLOCK DIAGRAM
PL REJECTION
FILTER
7th hp Fc = 300 hz
0.2 db ripple cheby
PL filter
6 pole LP
Fc = 252.5 hz
DPL FILTER
3 pole LP
Fc = 150 hz
From Rx out
(AFIC)
VOLUME
CONTROL
POT
TX AUDIO AFIC BLOCK DIAGRAM
MIC PRE AMP
FILTER
Gain = 20 db
300 hz 3 khz
PL clock
from uP(pA6)
March, 1997
DE-EMPH
1 pole LP
Fc = 231 hz
ALERT TONE
DIGITAL 8-BIT
GENERATOR
VOLUME ATT
1 POLE LP
Fc = 9 khz
SMOOTHING FILTER
1 POLE llp
Fc = 6050 hz
PA AUDIO
MC34119
&
EXT. COMP
PRE.EMPH AMP
6 db/oct
15 khz
3 khz
+3 db, 0 db, -3 db
PL Filter
PL/DPL
6 pole LP
1 pole LP
Fc = 252.5 hz
Fc = 1 khz
DPL Filter
3 pole LP
Fc = 150 hz
6 bit
PL/DPL
encoder
summing
smoothing
stage
BUFFER
1 pole LP
Fc = 9 khz
Fc = 9 khz
BUFFER
Fc = 30 khz
GAIN/BUFFER
STAGE
Fc = 15 khz
SPEAKER
Rated audio 250 mW (RMS)
Max. power = 0.5 Watt
24 OHM
SPLATTER FILTER
LIMITER
-24 db/oct
dev=3khz(25k)
2750 hz
1.5khz(12.5k)
Smoothing
4 bit dev.
filter
attn
1 pole LP
Fc = 6050 hz
5 bit dev.
attn.
Unattn.
Rx out
Rx out
PL/DPL
decorder
out
PA audio
VCO
MOD