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You see and hear the following terms and want to know more:
LTR
Logic Trunked Radio
is a system developed in the late 1970s by the E. F. Johnson Company.
Trunking for business and industry. Not suitable for public Safely or Emergency Services
by design.
EDACS
Enhanced Digital Access Communication System
A proprietary system created by General Electric back in the late 80's
Motorola™Trunking
P25
APCO Project 25
D-Star
CTCSS or PL™
Continous Tone Coded Squelch Signal or Private Line™
PL™ Private Line - Motorola, CG™ Channel Guard - General Electric QC™ Quiet Channel - RCA, QT™ Quiet Talk - Kenwood, TG™ ToneGuard - EF Johnson
In telecommunications, Continuous Tone-Coded Squelch System or CTCSS is a circuit that is used to reduce the annoyance of listening to other users on a shared two-way radio communications channel
It is sometimes called tone squelch. Where more than one user group is on the same channel (called co-channel users), CTCSS filters out other users if they are using a different CTCSS tone or no CTCSS.
Receivers equipped with a CTCSS circuit usually have a switch that selects normal mode or CTCSS mode. When enabled, the CTCSS radio circuit, instead of opening the receive audio for any signal, causes the two-way radio receiver's audio to open only in the presence of the normal RF signal AND the correct sub-audible audio tone (sub-audible meaning that the receiver circuitry can detect it, but is not apparent to the users in the audio output).
This is akin to the use of a lock on a door. A carrier squelch or noise squelch receiver not configured with CTCSS has no lock on its door and will let any signal in. A receiver with CTCSS circuitry (and with it enabled) locks out all signals except ones encoded with the correct tone. CTCSS can be regarded as a form of in-band signaling.
38 TIA/EIA standard tone frequencies
11 with asterisk are non-standard
1 in red is used in military
67.0 Hz
69.3 Hz*
71.9 Hz
74.4 Hz
77.0 Hz
79.7 Hz
82.5 Hz
85.4 Hz
88.5 Hz
91.5 Hz
94.8 Hz
97.4 Hz
100.0 Hz
103.5 Hz
107.2 Hz
110.9 Hz
114.8 Hz
118.8 Hz
123.0 Hz
127.3 Hz
131.8 Hz
136.5 Hz
141.3 Hz
146.2 Hz
150.0 Hz
151.4 Hz
156.7 Hz
159.8 Hz*
162.2 Hz
167.9 Hz
171.3 Hz*
173.8 Hz
177.3 Hz*
179.9 Hz
183.5 Hz*
186.2 Hz
189.9 Hz*
192.8 Hz
196.6 Hz*
199.5 Hz*
203.5 Hz
206.5 Hz*
210.7 Hz
218.1 Hz
225.7 Hz
229.1 Hz*
233.6 Hz
241.8 Hz
250.3 Hz
254.1 Hz
DCS or DPL™
Digital Coded Squelch or Digital Private Line™
DCS or Digital Private Line™ was created by Motorola Inc.
DCS (Digital-Coded Squelch) superimposes a continuous stream of FSKdigitaldata at 134.4 bits per second, on the transmitted signal. In the same way that a single CTCSS tone would be used on an entire group of radios, the same DCS code is used in a group of radios. DCS is also referred to as Digital Private Line (or DPL), another trademark of Motorola, and likewise, General Electric's implementation of DCS is referred to a Digital Channel Guard (or DCG). DCS is also called DTCS (Digital Tone Code Squelch) by Icom, and other names by other manufacturers. Radios with DCS options are generally compatible provided the radio's encoder-decoder will use the same code as radios in the existing system. Be aware that the same 23-bit DCS word can, for example, produce three different valid DCS codes due to the encoding architecture.
DCS will not work on phase modulated radios only on direct FM radios.
Explaination for the normal vs. inverted DPL™
DPL™ uses a codeword consisting of a 23-bit frame, transmitted (subaudible) at a data rate of 134.4 bps (bit/sec). Occasionally, signal inversion can result in the complement of a code to be sent or received. This prevents the receiver squelch from opening with DPL™ enabled, as the decoded bit sequence would not match that selected for the operation.
Typical situations that might cause inversion to occur are:
Connection of an external receiver preamplifier
Operating through a repeater
Connection of an external linear amplifier
Note that code inversion does not mean that any of the above listed equipment is defective.
In certain amplifier configurations, the output signal (phase) is inverted from the input. Small signal or power amplifiers having an odd number (1, 3, 5, etc.) of amplification stages may result in inversion of a transmitted or received DCS code.
There are 104 TIA/EIA DPL™ codes
Normal Inverted
023 047
025 244
026 464
031 627
032 051
036 172
043 445
047 023
051 032
053 452
054 413
065 271
071 306
072 245
073 506
074 174
114 712
115 152
116 754
122 225
125 365
131 364
132 546
134 223
143 412
145 274
152 115
155 731
156 265
162 503
165 251
172 036
174 074
205 263
212 356
223 134
225 122
226 411
243 351
244 025
245 072
246 523
251 165
252 462
255 446
261 732
263 205
265 156
266 454
271 065
274 145
306 071
311 664
315 423
325 526
331 465
332 455
343 532
346 612
351 243
356 212
364 131
365 125
371 734
411 226
412 143
413 054
423 315
431 723
432 516
445 043
446 255
452 053
454 266
455 332
462 252
464 026
465 331
466 662
503 162
506 073
516 432
523 246
526 325
532 343
546 132
565 703
606 631
612 346
624 632
627 031
631 606
632 624
654 743
662 466
664 311
703 565
712 114
723 431
731 155
732 261
734 371
743 654
754 116
XTCSS
New Technology!
Developed by CML, XTCSS is a squelch signalling format for radio systems, using both sub-audio (CTCSS) and in-band (XTC) signalling concurrently.
Many CTCSS channels can be employed in a single RF channel. Within the ‘leisure radio’ environment especially there is always the possiblity that other in range users will use the same, standard sub-audio tone, therefore causing interference and loss of privacy.
The implementation of XTCSS, an in-band tone and sub-audio signalling combination, provides, currently, up to 99 additional private channels within the single RF channel. The use of XTCSS signalling prevents ‘squelch breakthrough’ caused by other common-channel users.
DRM
Digital Radio Mondiale
and many others terms you may or may not understand.
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