Unlike CTCSS, DCS signal spectrum occupies considerable more bandwidth.

The FM deviation level of DCS data should be in the range of 500 to 800 Hz. At the end of the radio transmission and about 1/2 second before the transmitter un-keys, the radio will encode a 134 Hz tone that serves as a turn off code. Each code word is unique and all code words may be used on the same channel without interference. Unlike CTCSS (Continuous Tone Coded Squelch System) which uses continuous tones below 300 Hz., DCS uses digital data or code words. DCS is newer than CTCSS, and has more combinations. If they transmit with the same DCS as you, then your radio will unmute. If someone else transmits on the channel with a different or no DCS, the radio will not unmute. It sends a number repeatedly encoded in digital as you speak, in the low frequencies so you do not hear it. DCSĭCS works the same, apart from it being digital instead. The tone is then sometimes called ‘sub audible’ because it’s below the range of THEN audible voice frequencies – but it would be audible if played on full range speakers without the filtering that CTCSS radio receivers also use on receive (we can hear down to 20Hz or so). When CTCSS is used, the audio is filtered out below about 300Hz, so that the only audio frequency energy that ends up being transmitted between 0 and 300Hz is the CTCSS tone itself (almost always any one tone between 67 and 254.1 Hz). Different CTCSS codes have different frequencies, and this is how it filters out other people – as long as they have a different CTCSS, or no CTCSS, then your radio will not pass any audio to the speaker. It will also be heard if the radio has CTCSS and DCS off. Other radios must have the same CTCSS tone or code set to hear the transmission. Basically what it does is this: it adds a tone into your transmission at a certain frequency. Talk about What they are and what the difference of them? CTCSSĬTCSS stands for Continuous Tone Coded Squelch System.

Ctcss code