CTCSS/DCS codes ("Privacy" codes)
When using an FRS or GMRS radio (and some others), sometimes you can use a squelching technique to help with interference and extra noise (such as post-transmission noise). This is typically marketed as some form of "privacy" code but despite that, your transmission can be heard by anyone using the same frequency (channel) as you.
- If a radio receives a signal on a sub-channel (i.e. only activates for a specific CTCSS/DCS code) and someone else is transmitting on a different code, you end up with a noisy interfered signal. You can respond by changing your channel or by ignoring the interference and continuing to transmit anyway -- but you probably shouldn't do that. Alternatively, you can say hi to your new friends by switching off CTCSS/DCS.
Other FRS, GMRS, and ham radio pages
CTCSS codes
CTCSS (Continuous Tone-Coded Squelch System) is a technique where one low-frequency tone is broadcast with your audio. Receiving radios configured to a code will not turn on the speaker if it doesn't hear the code's tone over the air. Typically, a CTCSS aware receiver will strip out the tone.
The following codes should work on most FRS radios ("walkie-talkies") and the frequencies should work on most GMRS radios. DCS codes (see below) typically have higher sub-code numbers than CTCSS codes do, although sometimes a radio will have only one of CTCSS or DCS, or have them separated.
This list includes 38 codes and their corresponding frequencies. If you see 60 codes or less (typically around 40), your radio only supports CTCSS. If your radio has 121 or 38 codes, this list should be correct for the first 38.
- 1: 67.0 Hz
- 2: 71.9 Hz
- 3: 74.4 Hz
- 4: 77.0 Hz
- 5: 79.7 Hz
- 6: 82.5 Hz
- 7: 85.4 Hz
- 8: 88.5 Hz
- 9: 91.5 Hz
- 10: 94.8 Hz
- 11: 97.4 Hz
- 12: 100.0 Hz (not used in 50 Hz regions)
- 13: 103.5 Hz
- 14: 107.2 Hz
- 15: 110.9 Hz
- 16: 114.8 Hz
- 17: 118.8 Hz
- 18: 123.0 Hz
- 19: 127.3 Hz
- 20: 131.8 Hz
- 21: 136.5 Hz
- 22: 141.3 Hz
- 23: 146.2 Hz
- 24: 151.4 Hz
- 25: 156.7 Hz
- 26: 162.2 Hz
- 27: 167.9 Hz
- 28: 173.8 Hz
- 29: 179.9 Hz
- 30: 186.2 Hz
- 31: 192.8 Hz
- 32: 203.5 Hz
- 33: 210.7 Hz
- 34: 218.1 Hz
- 35: 225.7 Hz
- 36: 233.6 Hz
- 37: 241.8 Hz
- 38: 250.3 Hz
- Some NATO military radios include a 150.0 Hz CTCSS tone.
Motorola Private Line codes (1Z, ZA, 2B, M7, etc)
Complete list of CTCSS frequencies
DCS codes
DCS (digital code squelching) uses a three-octal (that is, 000 to 777, or three bits) digital code transmitted at a low frequency in your audio. Apart from that, it functions pretty much identical to CTCSS.
This list includes the with-CTCSS and without-CTCSS "privacy codes", in that order, followed by the digital information represented as octals. If your radio has 121 or 83 codes, this list should be correct for it, but if it doesn't, check for the brand below.
- 39/1: 023
- 40/2: 025
- 41/3: 026
- 42/4: 031
- 43/5: 032
- 44/6: 043
- 45/7: 047
- 46/8: 051
- 47/9: 054
- 48/10: 065
- 49/11: 071
- 50/12: 072
- 51/13: 073
- 52/14: 074
- 53/15: 114
- 54/16: 115
- 55/17: 116
- 56/18: 125
- 57/19: 131
- 58/20: 132
- 59/21: 134
- 60/22: 143
- 61/23: 152
- 62/24: 155
- 63/25: 156
- 64/26: 162
- 65/27: 165
- 66/28: 172
- 67/29: 174
- 68/30: 205
- 69/31: 223
- 70/32: 226
- 71/33: 243
- 72/34: 244
- 73/35: 245
- 74/36: 251
- 75/37: 261
- 76/38: 263
- 77/39: 265
- 78/40: 271
- 79/41: 306
- 80/42: 311
- 81/43: 315
- 82/44: 331
- 83/45: 343
- 84/46: 346
- 85/47: 351
- 86/48: 364
- 87/49: 365
- 88/50: 371
- 89/51: 411
- 90/52: 412
- 91/53: 413
- 92/54: 423
- 93/55: 431
- 94/56: 432
- 95/57: 445
- 96/58: 464
- 97/59: 465
- 98/60: 466
- 99/61: 503
- 100/62: 506
- 101/63: 516
- 102/64: 532
- 103/65: 546
- 104/66: 565
- 105/67: 606
- 106/68: 612
- 107/69: 624
- 108/70: 627
- 109/71: 631
- 110/72: 632
- 111/73: 654
- 112/74: 662
- 113/75: 664
- 114/76: 703
- 115/77: 712
- 116/78: 723
- 117/79: 731
- 118/80: 732
- 119/81: 734
- 120/82: 743
- 121/83: 754
Other sub-codes
Some radios use a different set of codes. Consult your manual for more details.