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Band-energy near-end echo reducer for tonal signalling detectors

  • US 5,631,957 A
  • Filed: 03/09/1995
  • Issued: 05/20/1997
  • Est. Priority Date: 03/09/1995
  • Status: Expired due to Term
First Claim
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1. Echo reducer for tonal signalling detectors, comprising:

  • a transmission line conveying transmit signals to a system hybrid connected to a phone line;

    a reception line conveying remote signals from the system hybrid, said remote signals including a near-end echo of the transmit signals;

    a first filter bank including a first bandpass filter for filtering and integrating the transmit signals and a first squarer for determining an absolute level of an output of the first bandpass filter, said first filter bank having a first output;

    a second filter bank including a second bandpass filter for filtering and integrating the remote signals and a second squarer for determining an absolute level of an output of the second bandpass filter, said second filter bank having a second output;

    a multiplier, connected to the first filter bank, for multiplying the first output by a compensator gain coefficient and producing a resultant signal; and

    an adder for subtracting the resultant signal from the second output, and producing a receive signal from which the near-end echo has been reduced.

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