Description - JRC JSS-296 Service Manual

6.3.1 Descriptions
NCT-196N DSC/NBDP modem consists the control board type CDJ-1999N, the W/K RF AMP
type CAF-450, W/K control type CDJ-1701 and the Mother board type CQC-1962.
The W/K RF AMP consists the RF filter, RF amplifier, IF amplifiers, IF filters, mixers and BK
relay. It converts the received RF signal to audio frequency and passes it to the W/K control. The
scanning frequencies are controlled by the W/K control.
The W/K control consists 1
returns the audio signal that comes from the control board back directly. When it detects the dot
signal in the audio signal that comes form the W/K RF AMP, it activate the DOT DET signal and
pass the audio signal from the W/K RF AMP through to the control board. And keep the
connection until dot reset signal from the control board has been activated.
The control board consists the 20MHz TCXO, Main CPU, Sub CPU, mark/space modulator and
decoder. It receives the audio frequency from the transceiver type JSB-196GM and pass through
it directly to the W/K control. The W/K control returns back the audio signal and it is inputted to
mark/space decoder.
If the DOT DET signal form the W/K control is activated and the control board detects the DSC
message addressed to own station in the audio signal, it stores the received DSC message in its
memory and sounds the DSC alert. The control board activates the DOT RESET signal to the
W/K control, after finishes the decoding or decides the DSC file is not addressed to own station
during decoding.
At the DSC mode, the control board converts the DSC file to be sent in its memory to
modulated audio frequency and send it to the JSB-196GM through the line out. The control board
decodes the audio signal from the JSB-196GM. If it detects the DSC message that addressed to
own station, it stores the DSC file in its memory and sounds the DSC alert.
At the NBDP mode, the control board is phasing to other station. After finish the phasing, the
control board just decodes and modulates the audio frequency from/to JSB-196GM and pass
characters from/to the data terminal NDZ-127J.
* The modem NCT-196N and the DTE NDZ-127J share the Printer NKG-800. The printer is
connected via automatic printer selector type SW-ATB21K.
st
local synthesizer, CPU and mark/space signal decoder. Normally it
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