CTCSS Tone Chart
CTCSS stands for Continous Closed Squelch System, (often called Private Line, Channel Guard, Quiet Channel, Call Guard) it's purpose in a radio system is to make the radio repeater system accessable to many groups of users, while allowing only each group to hear only it's own radio transmissions. Mobile radios on a CTCSS radio system emit a tone when the user pushes the 'push to talk button' the transmitter emits a tone to idenify itself to all other two way radios using the same radio system. Only radios that are encoded with the same tone that is transmitted, when recieving the tone will allow the transmission to be heard. A few of the high end scanners on the market can use this method for isolating only the transmissions that the user want to monitor. CTCSS based radio systems are losing favor with public safety agencies, 800 MHz trunked radio systems now becoming favorable. CTCSS is used in the new Family Radio Service (FRS)
More Information on CTCSS
| XZ | 67.0 | 1Z | 100.0 | 4A | 141.3 | MA | 203.5 |
| XA | 71.9 | 1A | 103.5 | 4B | 146.2 | 8Z | 206.5 |
| WA | 74.4 | 1B | 170.2 | 5Z | 151.4 | M2 | 210.7 |
| XB | 77.0 | 2Z | 110.9 | 5A | 156.7 | M3 | 218.1 |
| WB | 79.7 | 2A | 114.8 | 5B | 162.2 | M4 | 225.7 |
| YZ | 82.5 | 2B | 118.8 | 6Z | 167.9 | M5 | 233.6 |
| YA | 85.4 | 3Z | 123.0 | 6A | 173.8 | M6 | 241.8 |
| YB | 88.5 | 3A | 127.3 | 6B | 179.9 | M7 | 250.3 |
| ZZ | 91.5 | 3B | 131.8 | 7Z | 186.2 | |
| ZA | 94.8 | 4Z | 136.5 | 7A | 192.8 | |
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