call sign(redirected from Call letter)
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call sign[′kȯl ‚sīn]
a set of characters (code symbols, letters, or numbers) or an audible signal (word, musical phrase, bird call) that serves as the distinctive sign of a radio station—usually for the purpose of identification of the station during reception. As a rule, it is transmitted at the beginning of each period of the station’s operation.
The set of symbols in a call sign identifies the station’s national affiliation. The initial characters are established by the International Radio Regulations. The USSR, for example, uses in this position the letters U and R and such combinations as 4J, 4K, and 4L. The complete structure of a call sign depends on the class (purpose) of a station and differs for broadcasting, official, and amateur radio stations. Call signs for amateur radio stations have a complicated makeup and contain the most information. They often indicate through a code the station’s operating wave band (shortwave or ultrashortwave), the station’s group (a collective or individual station) and site (in the USSR—the Union republic, oblast, and amateur-radio region), and the individual letter symbol or registration number of the station.
I. V. KAZANSKII