Alinco DR-635E Instruction Manual download pdf (Page 45)

Selective Communication

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DET setting

If the DET mode in DCS operation is preferred, press the H/L key while the 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 a

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

stream is modulated with a 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 a 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 a DCS stream. By activating DET, the receiver opens the squelch when the first corre-

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

DCS squelch remains opened.

Advantage of DET

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

a corresponding DCS coded signal is received.

Disadvantage of DET

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

selective-calling technique and transmitting at the same time. After station A with its corre-

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

squelch by his signal alone.

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Alinco DR-635E Instruction Manual Page 45