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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.
That is why I have created this page!
 
 
Documents
(Coming Very soon)
 
 
 
 
 
 
 
 
 
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