JPS5698942A - Tone squeltch system - Google Patents

Abstract

PURPOSE:To minimize the missing in beginning of talking in call and to enable quick call, by inserting a delay restored type delay circuit to the detected output of circuit and coupling the press-to-talk signal. CONSTITUTION:Electromagnetic waves of opposing station are discriminated at the discriminator 1, and the tone of the station is filtered at the filter 5, and tone amplification 6 is made and detected 7 and fed to a delay restored type delay circuit 22. Further, via the circuit 22, the logic level ''1'' is fed to the coincidence circuit 8. On the other hand, in the noise squeltch signal, ''1'' is fed to the coincidence circuit from the inverter circuit 4 and on-instruction is given to the voice switch circuit. When the electromagnetic waves from opposing station are stopped and press-to- talk is made for response, the output of the circuit 22 keeps the output for, e.g., 10 seconds after the end of the press-to-talk. Thus, when the waves are received from the opposing station within 10 seconds, since the output of the circuit 22 is fed to the circuit 8, audio is output from the speaker, allowing to minimize the missing of talk beginning and to make quick call.