The CTCSS system ( C ontinuous T one-coded S quelch S ystem) is a noise-canceling system encoded by a continuous tone [1] or a “friend / foe” signal identification system [2] , designed to divide users working in the same frequency range into groups . Users (correspondents) from the same group can hear each other thanks to the identification code.
Features
- The number of CTCSS codes (tones) flashed in a radio station is different: from a dozen in the simplest models, it can reach 50. In LPD and PMR radio stations, typically 38, in amateur radio stations, 39. [3]
As a rule, frequencies below the range of the speech signal are used - from 67 to 257 Hz.
Interesting Facts
- There are other CTCSS notations:
- PL (Private L ine - Private Line) - Motorola
- CG ( C hannel G uard - Channel Protection) - Ericsson
- QT ( Q uiet T alk - Quiet Talk) - Kenwood
- In practice, when communicating between different types of radio stations, it is better to agree not on the subton number, but on its frequency, according to the instruction manual.
- The best choice of frequency is not too low ( due to the increase in the detection time of the tone ) and not too high ( due to conflicts with the speech signal in the cheapest models of radio stations ) frequency values - optimally somewhere from 120 to 200 Hz ; at the same time, frequencies that are multiples of the frequency of the alternating current network ( for Russia - 50 Hz ) should be avoided - that is, adjacent to 100, 150 and 200 Hz.
Notes
- ↑ Radio communication with low-power radio stations . Date of treatment January 30, 2014.
- ↑ Mechanisms for the artificial separation of the operating frequency (Inaccessible link) Archived on November 9, 2010.
- ↑ Mike Morris WA6ILQ. CTCSS tone numbers are useless! . Date of treatment January 30, 2014.