other to the point where it is impossible to clearly receive any of the stations. A scanner equipped with CTCSS and DCS (like your scanner) can code each received frequency with a specific CTCSS or DCS frequency. Then, when you receive multiple signals, you only hear the transmission with the CTCSS or DCS tone you programmed. If you do not receive the correct tone with a signal, the scanner’s squelch remains closed and you hear nothing.
Local frequency allocation groups set cooperative standards to establish the CTCSS and DCS tone for each transmitter (or repeater).
You can search for the following CTCSS frequencies and DCS codes.
CTCSS Frequencies (Hz)
67.0 | 69.3 | 71.9 | 74.4 | 77.0 | 79.7 | 82.5 | 85.4 | 88.5 | 91.5 |
94.8 | 97.4 | 100.0 | 103.5 | 107.2 | 110.9 | 114.8 | 118.8 | 123.0 | 127.3 |
131.8 | 136.5 | 141.3 | 146.2 | 151.4 | 156.7 | 159.8 | 162.2 | 165.5 | 167.9 |
171.3 | 173.8 | 177.3 | 179.9 | 183.5 | 186.2 | 189.9 | 192.8 | 196.6 | 199.5 |
203.5 | 206.5 | 210.7 | 218.1 | 225.7 | 229.1 | 233.6 | 241.8 | 250.3 | 254.1 |
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DCS Codes (Octal) |
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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 | 654 | 662 | 664 | 703 | 712 | 723 | 731 |
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| 732 | 734 | 743 | 754 |
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Conventional Scanning
Conventional scanning is a relatively simple concept. Each group of users in a conventional system is assigned a single frequency (for simplex systems) or two frequencies (for repeater systems). Any time one of them transmits, their transmission always goes out on the same frequency. Up until the late 1980’s this was the primary way that radio systems operated.
Even today, there are many
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