Kongsberg Simrad RA83, Service Manual

Page: 16 / 210

The buffer amplifier U8 invert the receive signal(negative video) to positive signal. Then, detect
the peak level with peak detect circuit U10, CR1, CR3, C23, R26, and R27. The analogue switch
U9 is a reset switch for detected peak level signal. The detected peak signal is sampled & hold
with U11, U12, U13, R29, and C34, and output as the receive signal(SH-RX).
(4) Transmitter timing generator
The analogue switch U9 is a peak detect circuit for the transmit signal(PM SIG). The 15 us width
control signal(ASW2/ASW2N) for the analogue switch U9 is generated from 1 us width transmit
trigger(TRG3) on the modulator PCB.
The 20 us width sampling signal(SH2) for sample & hold circuit is generated based from TRG3.
(5) Peak detector and sample & hold circuit for transmitter system
The peak detector detects the peak level of the transmit signal(PM SIG) with the peak detect
circuit U9, U10. The analogue switch U9 is a reset circuit for the detected peak level. The peak
level is output as transmit signal(SH-TX) after sample & hold processing with U11, U12, U13.
(6) Signals
PM ON/OFF The ON/OFF control signal for KPM-20.
PM TUNE The tuning voltage signal(5V to 10V) for the receiver module of the
KPM-20.
E41-1000
KPM-20
E41-1000
E41-1000
E41-1000
12V
(2) Receiver
timing generator
GND
TRG3
PM ON OFF
PM TUNE
5V
5V
KPM-20
KPM-20
-5V
(1) Power supply
for -5V
E41-1000
E41-1000
5V
-5V
GND
TRG2
(4) Transmitter
timing generator
-5V 5V
(3) Peak detect
or,
S
ample & Hold
(5) Peak detector,
Sample & hold
circuit for
transmitter
system
E41-1000
5V
VIDEO
SH RX
PM GATE
E41-1000
SH TX
KPM-20
E41-1000
PM TRG
KPM-20
PM SIG
E41-1000
E41-1000
KPM-20
PM ON OFF
KPM-20
PM TUNE
KPM-20
-5V 5V
5V
KPM-20
Fig. 2.1.7. Block Diagram for control PCB
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