Portable telephone system having a battery saver feature

• US 3,962,553 A
• Filed: 10/29/1974
• Issued: 06/08/1976
• Est. Priority Date: 03/29/1973
• Status: Expired due to Term

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Eness, Orville M., Linder, Donald L., Lynk, Charles N. Jr.
• Primary Examiner(s): Claffy, Kathleen H.
• Assistant Examiner(s): Brigance, Gerald L.
• Application Number:
  US05/518,827
• Time in Patent Office: 588 Days
• Field of Search: 179/41 A, 179/1 VC, 179/81 B, 179/1 HF, 325/16, 325/22, 325/55, 325/64, 325/151, 325/152, 325/187, 343/176
• US Class Current: 455/462
• CPC Class Codes: H03G 3/34 Muting amplifier when no signal is present or when only weak signals are present, or caused by the presence of noise signals, e.g. squelch systems
• CPC Class Codes: H03G 3/341 Muting when no signals or only weak signals are present H03G3/344, H03G3/345 take precedence
• CPC Class Codes: H03G 3/344 Muting responsive to the amount of noise (noise squelch) H03G3/345 takes precedence
• CPC Class Codes: H04B 1/46 by voice-frequency signals; by pilot signals
• CPC Class Codes: H04B 1/50 using different frequencies for the two directions of communication
• CPC Class Codes: H04M 1/73 Battery saving arrangements
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A battery saving system for a portable duplex communications system such as a portable telephone system includes a voice operated transmitter within each portable unit which automatically transmits radio signals upon application of audio signals thereto and discontinues transmission upon termination of the audio signals to conserve battery power. A companion receiver includes a fast acting squelch system to substantially eliminate the noise bursts occurring between transmissions by said portable unit.

Claims

1. A full duplex radio communication system including in combination:

a base station having base frequency modulated transmitter means for providing radio signals having a first carrier frequency and base frequency modulated receiver means including frequency modulation detector means for simultaneously receiving radio signals having a second carrier frequency different than said first carrier frequency, said base receiver means having an audio output circuit and noise operated squelch circuit means for muting said audio output circuit, said squelch circuit means being connected to the frequency modulation detector means of said base receiver means and responsive to radio frequency signals received by said base receiver for rendering said audio output circuit operative upon receipt of radio signals by said base receiver and for muting said output circuit upon termination of said received radio frequency signals, said squelch circuit having a response time of less than approximately 10 milliseconds for rendering said audio output circuit operative in substantial synchronism with the receipt of said second carrier frequency radio signals, and for rapidly muting said audio output circuit upon termination of said received radio signals to render noise bursts provided by said base receiver means in the absence of received signals substantially inaudible; and

a personal portable unit adopted to be carried by an individual and having portable transmitter means for providing radio frequency signals having said second carrier frequency and portable receiver means for simultaneously receiving radio signals having said first carrier frequency, said portable unit including a battery sufficiently small to be carried easily by the individual operating said portable unit for providing limited power to said portable unit, said portable unit having transducer means connected to said portable transmitter means for receiving voice signals and modulating said transmitter in accordance therewith, and voice detector means connected to said transducer means and to said portable transmitter means, said voice detector means being responsive to the voice signals applied to said transducer means for rendering said transmitter means operative within less than approximately 5 milliseconds following the application of voice signals to said transducer means to provide said second carrier frequency radio signals when voice signals are applied to said transducer means and for maintaining said portable transmitter means operative for more than approximately one-half second following the termination of said voice signals, said transmitter means being rendered inoperative with no signals applied to said voice detector.

2. A radio communication system as recited in claim 1 wherein said base station includes means for connecting said base transmitter means and said base receiver means to a telephone network.

3. A radio communication system as recited in claim 2 wherein said portable unit includes a circuit for generating a plurality of signaling tones connected to said portable transmitter means, and a plurality of push buttons for rendering said tone generating circuit operative to generate predetermined ones of said signaling tones for modulating said portable transmitter means.

4. A radio communication system as recited in claim 3 wherein said signaling circuit is coupled to said voice detector means, said voice detector means being responsive to tones generated by said signaling circuit for rendering said portable transmitter means operative.

5. A radio communication system as recited in claim 1 wherein said squelch circuit means includes means for extending the response time thereof upon receipt of a signal by said base receiver means having an amplitude below a predetermined level.

6. A radio communication system as recited in claim 4 wherein said voice detector means includes means for maintaining said portable transmitter means inoperative until said voice signals exceed a predetermined amplitude.

7. In a telephone system a duplex, battery powered personal portable unit small enough to be easily carried by an individual having a portable transmitter and a portable receiver, and a fixed station having a fixed transmitter and a fixed receiver for transmitting radio signals to and receiving radio signals from said portable unit, the method of conserving the battery power of the portable unit, comprising the steps of:

providing a voice responsive circuit coupled to said portable transmitter, said voice responsive circuit being operative to cause said portable transmitter to transmit radio signals in response to audio signals applied thereto, and to render said portable transmitter inoperative upon termination of said audio signals;

applying audio signals to said voice responsive circuit to render said portable transmitter operative to transmit radio signals in response to said audio signals; and

providing muting means connected to said fixed receiver, said muting means being responsive to radio signals received by said fixed receiver to render said fixed receiver operative to provide audio signals in response to said radio signals and to mute said receiver in the absence of radio signals, said muting means having a rapid response time to render said fixed receiver operative in substantial synchronism with the operation of said transmitter, and to rapidly mute said receiver upon termination of said radio signals to render noise bursts generated by said fixed receiver upon termination of said radio signals substantially inaudible.

8. A duplex radio telephone system for use in conjunction with a telephone network, said system including in combination:

fixed station frequency modulated receiver means including an FM detector circuit for providing audio signals to said telephone network in response to radio signals received thereby, said receiver means providing noise signals in the absence of received radio signals;

personal portable transmitter means powered by a battery small enough to be easily carried by an individual for transmitting radio signals to said fixed station receiver means;

voice responsive switch means connected to said portable transmitter means, said voice responsive switch means being responsive to voice signals applied thereto for rendering said portable transmitter means operative to transmit radio signals in response to said voice signals and rendering said portable transmitter means inoperative when no signal is applied to said switch means;

coupling means connected to said fixed station receiver means for applying said audio signals to said telephone network;

squelch means including a noise operated squelch circuit connected to the FM detector circuit of said fixed station receiver means and to said coupling means, said squelch means being responsive to said receiver means for rendering said coupling means operative to apply said audio signals to said telephone network when radio signals are received by said receiver means, and responsive to noise signals generated by the FM detector circuit of said receiver means for rendering said coupling means inoperative to prevent the application of the noise signals to said telephone network in the absence of radio signals, said squelch means having a response time of less than approximately 10 milliseconds for rendering said coupling means operative in substantial synchronism with the operation of said portable transmitter means to substantially prevent the application of the noise signals to said telephone network upon termination of said radio signals.

9. A radio telephone system as recited in claim 8 wherein said squelch circuit includes means for extending the response time thereof to more than 100 milliseconds.