two-tone keying
Telecommunications
In telegraphy systems, keying in which the modulating wave causes the carrier to be modulated with a single tone for the "mark" and modulated with a different single tone for the "yyspace."
In telegraphy systems, keying in which the modulating wave causes the carrier to be modulated with a single tone for the "mark" and modulated with a different single tone for the "yyspace."