5.4 TX/RX Board (05P0733)
5-25
5.4.3 Transmitter/Receiver circuit
AF circuit
The audio signal from the control unit is connected to TX/RX board via T-IF and
T-CPU boards.
Main CPU on T-CPU board sends DSC and NBDP messages to DSP for AFSK (Audio
Frequency Shift Keying) modulation or to generate 1700 Hz+85 Hz signal. The
modulated DSC and NBDP signal is supplied to TX/RX board. For reception, the signal
flows in reverse.
The AF signal or LINE IN and LINE OUT signals to and from TX/RX board is –10
dBm/600 Ω.
Fig.5.4.3 Block diagram of LINE IN/OUT circuit
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