Abstract The present invention is directed to a monitor circuit for use in a communication receiver including an input circuit and a detecting circuit having applied thereto a carrier signal carrying intelligence from a transmitter, the monitor circuit comprising a monitor input circuit having the input thereof coupled to the detecting circuit and an output, the monitor input circuit being responsive to the application of the carrier signal to the receiver for providing a control signal on the output thereof, a monitor switch connected to the output of the monitor input circuit and having a first inoperative condition and a second operative condition, and a monitor indicator coupled to the monitor switch, the monitor switch being responsive to the application thereto of the control signal for actuating the monitor switch from the first inoperative position thereof to the second operative position thereof to operate the monitor indicator.
A receiver for responding to a fixed frequency carrier wave modulated by at least one control tone and by audio signals, said receiver comprising an input circuit for selectively receiving a carrier wave having the fixed frequency, a detector circuit coupled to said input circuit for detecting the audio signals and the control tone, an audio amplifier circuit coupled to said detector circuit for amplifying the audio signals therefrom, a speaker coupled to said audio amplifier circuit for converting the audio signals into sound waves, a squelch circuit having an input coupled to said detector circuit and an output coupled to said audio amplifier circuit and being operative in a first condition thereof to render said audio amplifier circuit inoperative and operative in a second condition thereof to render said audio amplifier circuit operative, a tone control circuit having an input coupled to said detector circuit and having an output coupled to said squelch circuit, said tone control circuit being responsive to the presence of the control tone for actuating said squelch circuit from the first condition thereof to the second condition thereof to render said audio amplifier circuit operative, a monitor input circuit having an input coupled to said detector circuit and having an output, said monitor input circuit providing at the output thereof a first control signal of a first value when a carrier wave having the fixed frequency is applied to the receiver and a second control signal of a second value in the absence of a carrier wave having the fixed frequency, a monitor switch having an input coupled to the output of said monitor input circuit and having a first condition when said first control signal is applied thereto and having a second condition when said second control signal is applied thereto, and a monitor indicator coupled in a circuit with said monitor switch and being placed in a first condition when said monitor switch is in the first condition thereof and being placed in a second condition when said monitor switch is in the second condition thereof, whereby when said monitor indicator is in said first condition thereof an operator of the receiver is apprised that the channel represented by a carrier wave of the fixed frequency is already being used and is apprised when said monitor indicator is in the second condition thereof that said channel is not being used.
Claim 2
Dependent Claim
397 words
A receiver for responding to a fixed frequency carrier wave modulated by at least one control tone and by audio signals, said receiver comprising an input circuit for selectively receiving a carrier wave having the fixed frequency, a detector circuit coupled to said input circuit for detecting the audio signals and the control tone, an audio amplifier circuit coupled to said detector circuit for amplifying the audio signals therefrom, a speaker coupled to said audio amplifier circuit for converting the audio signals into sound waves, a squelch circuit having an input coupled to said detector circuit and an output coupled to said audio amplifier circuit and being operative in a first condition thereof to render said audio amplifier circuit inoperative and operative in a second condition thereof to render said audio amplifier circuit operative, a tone control circuit having an input coupled to said detector circuit and having an output coupled to said squelch circuit, said tone control circuit being responsive to the presence of the control tone for actuating said squelch circuit from the first condition thereof to the second condition thereof to render said audio amplifier circuit operative, a monitor input circuit having an input coupled to said detector circuit and having an output, said monitor input circuit providing at the output thereof a first control signal of a first value when a carrier wave having the fixed frequency is applied to the receiver and a second control signal of a second value in the absence of a carrier wave having the fixed frequency, a monitor switch having an input coupled to the output of said monitor input circuit and having a first condition when said first control signal is applied thereto and having a second condition when said second control signal is applied thereto, and a monitor indicator coupled in a circuit with said monitor switch and being placed in a first condition when said monitor switch is in the first condition thereof and being placed in a second condition when said monitor switch is in the second condition thereof, whereby when said monitor indicator is in said first condition thereof an operator of the receiver is apprised that the channel represented by a carrier wave of the fixed frequency is already being used and is apprised when said monitor indicator is in the second condition thereof that said channel is not being used.
Claim 3
Dependent Claim
14 words
The receiver set forth in claim 1, wherein said monitor indicator is a lamp.
Claim 4
Dependent Claim
26 words
The receiver set forth in claim 1, wherein said monitor switch is closed in said first condition thereof and is opened in the second condition thereof.
Claim 5
Dependent Claim
47 words
The receiver set forth in claim 1, wherein said monitor indicator is a lamp coupled in series with said monitor switch, said monitor switch being closed in the first condition thereof to illuminate said lamp and being opened in the second condition thereof to extinguish said lamp.