Alinco DR-635 - Manual (Page 45)

43
Selective Communication
023 025 026 031 032 036 043 047 051 053 054 065
071 072 073 074 114 115 116 122 125 131 132 134
143 145 152 155 156 162 165 172 174 205 212 223
225 226 243 244 245 246 251 252 255 261 263 265
266 271 274 306 311 315 325 331 332 343 346 351
356 364 365 371 411 412 413 423 431 432 445 446
452 454 455 462 464 465 466 503 506 516 523 526
532 546 565 606 612 624 627 631 632 645 654 662
664 703 712 723 731 732 734 743 754
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.