User's Manual Part 2

Selective Communication

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DET setting

In case DET mode in DCS operation is preferred, press H/L key while DCS code is displayed in the

setting mode. Observe that a decimal point appears then follow the remaining sequence to set the

parameter and exit.

DET on DCS function stands for Detect-Only mode. In DCS operation, the TX signal carries

digital code such as 001010000 determined by setting the 3-digit code such as 123,124 etc. This

stream is modulated with very low sub-audible frequency. The RX side, just like TSQ, detects this

stream and determines the squelch operation. This DCS code stream is transmitted all the way

through the communication like CTCSS tone (in this case a single continuous tone, instead of

digital coded stream).

It is necessary for receiver to correctly and CONTINUOUSLY receive this DCS digital stream to

hold the squelch open, otherwise the CPU thinks that the signal is unwanted and it closes the

squelch. But due to noise or weak signal strength etc, sometimes it is difficult to continuously

receive DCS stream. By activating DET, the receiver opens squelch when the first corresponding

DCS stream is received, then thereafter, regardless of the status of DCS codes the DCS squelch

remain opened.

Advantage of DET

It enables DCS squelch operation even in poorer condition, opening the squelch only when

corresponding DCS coded signal is received.

Disadvantage of DET

When it is activated, and suppose 2 stations are sharing the same channel with using DCS

selective-calling technique and transmitting at the same time, after the station A with corre-

sponding DCS is gone, you may still hear the station B although he can't open your DCS

squelch by his signal alone.