LOOP COMMUNICATION SYSTEM

• US 3,601,550 A
• Filed: 03/21/1969
• Issued: 08/24/1971
• Est. Priority Date: 03/21/1969
• Status: Expired due to Term

• Current Assignee: John G. Spracklen
• Original Assignee: John G. Spracklen
• Inventors: Spracklen, John G.
• Primary Examiner(s): Claffy, Kathleen H.
• Assistant Examiner(s): Helvestine, William A.
• Application Number:
  US04/809,356
• Time in Patent Office: 886 Days
• Field of Search: 179/82 325/320,349,369
• US Class Current: 455/41.1
• CPC Class Codes: H04B 5/00 Near-field transmission systems, e.g. inductive or capacitive transmission systems

Abstract

A limited-range, induction-coupled loop communication system for the transmission of audio information to a receiver located within the loop uses a frequency-modulated carrier-wave signal to transmit audio information to one or more receivers located within the loop. Each receiver has a pair of pickup coils preferably mounted at 90* relative to each other and a phaseshifting network connected to each of their outputs to thereby create a quadrature relationship in the received signals to substantially eliminate the occurrence of null conditions with variations in receiver orientation.

Claims

1. S A limited-range, induction-coupled communication system for the wireless transmission of information to a receiver located within a predetermined limited space, comprising:

means for providing a carrier-wave signal having a predetermined center frequency and modulated with a signal representative of said information;

transmitter means including a closed-loop antenna for transmitting said carrier-wave signal to said space and establishing therein an electromagnetic radiation field having a predetermined direction;

input circuit means for receiving said carrier-wave signal, including a pair of input transducers each having a maximumsignal-coupling axis orthogonally oriented relative to each other, each said input transducer providing a separate output signal representative of said modulated carrier-wave signal;

phase-shifting networks respectively coupled to said input transducers and providing phase shifts of substantially 45* and 135* respectively for establishing a quadrature phase relation between said output signals;

means for combining said separate phase-shifted output signals;

detector means responsive to said combined output signal for recovering said modulation signal; and

output transducer means for converting said recovered modulation signal into output information corresponding to that transmitted

2. A receiver adaptable for use with a limited-range, induction-coupled communication system of the type including a transmitter employing a carrier-wave signal modulated with a signal representative of information for transmission to a predetermined limited space by establishing an electromagnetic field having a predetermined direction in said space, said receiver comprising:

input circuit means for receiving said modulated carrier-wave signal, including a pair of input transducers each having a maximum-signal-coupling axis orthogonally oriented relative to each other, each said input transducer providing a separate output signal representative of said audio-modulated carrier-wave signal;

phase-shifting networks respectively coupled to said input transducers and providing phase shifts of substantially 45* and 135* respectively for establishing a quadrature phase relation between said output signals;

means for combining said separate phase-shifted output signals;

detector means responsive to said combined output signal for recovering said modulation signal; and

output transducer means for converting said recovered moduLation signal into output information corresponding to that transmitted.