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Shortwave and Scanner Listener

Resources

Shortwave Listener / Amateur Radio Stuff

  • Worldwide Marine Radio Facsimile Broadcast Schedules 10 FEB 12 CLICK



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!

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