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Ccitt 5-tones.jpg
Frequencies 30 MHz,800 MHz
Frequency Range 30 MHz - 800 MHz
Mode NFM
Modulation MFSK
Emission Designator
Bandwidth 5 kHz
Location Worldwide
Short Description CCITT is a 5-tone selcall system for VHF/UHF radios.
I/Q Raw Recording
Audio Sample

CCITT is a 15 tone selcall system for VHFVery High Frequency (30-300 MHz)/UHFUltra High Frequency (300-3000 MHz) radios. CCITT stands for Consultative Committee for International Telephony and Telegraphy, which has now become the ITU-T.

Selcall (selective calling) is a type of squelch protocol used in radio communications systems, in which transmissions include a brief burst of sequential audio tones. Receivers that are set to respond to the transmitted tone sequence will open their squelch, while others will remain muted.

CCITT has 100 msmilliseconds (.001 of a second) tone duration per tone. Each tone corresponds with either a number or letter, as denoted by the table below. CCITT has 15 tones to choose from, but only sends a burst of up to 5 tones. The bursts transmit right before a radio transmission.



Full Range 5-tone Burst
Ccitt 5-tones.jpg

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