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Voice-switched telephone set

  • US 4,162,374 A
  • Filed: 12/29/1977
  • Issued: 07/24/1979
  • Est. Priority Date: 12/31/1976
  • Status: Expired due to Term
First Claim
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1. A loudspeaker telephone set comprising:

  • a transmitter channel comprising in series a microphone, transmitter attenuator, transmitter amplifier, and duplexer;

    a receiver channel comprising in senes said duplexer, receiver attenuator, and loudspeaker;

    means for detecting a transmitter channel speech signal present at the transmitter attenuator output;

    means for detecting a receiver channel speech signal at the receiver attenuator output;

    means for adding said detected transmitter and receiver speech signals, thereby forming a summed signal;

    means for connecting said summed signal to a control terminal on each of said transmitter attenuator and receiver attenuator, andsaid transmitter amplifier means comprising an amplifier multiplier formed by a balanced modulator having two inputs respectively receiving the transmitter channel speech signal and the detected transmitter channel speech signal.

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