|
Continuous Tone Coded/Controlled Squelch System (CTCSS) The CTCSS system allows different groups of users to use a single frequency without hearing each other transmissions. With CTCSS equipped radios a sub-audible tone is transmitted along with the voice transmission. There are currently about 40 tones which can be used. When the CTCSS is activated the radio will only allow received signals, which carry the correct sub-audible tone to open the squelch, i.e. pass the voice signal to the loudspeaker. Transmissions with the wrong or without CTCSS tone will not be heard. To minimise the possibility of an operator transmitting when the frquency is in use by someone using a different CTCSS tone, most radios with CTCSS have a 'busy' indicator, which shows when the radio is receiving a signal that isn't opening the squelch.
|
