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Echo cancellation in a full-duplex speakerphone

  • US 5,323,458 A
  • Filed: 10/25/1993
  • Issued: 06/21/1994
  • Est. Priority Date: 10/25/1993
  • Status: Expired due to Fees
First Claim
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1. In a full-duplex speakerphone system, an apparatus for direct-path echo cancellation, comprising:

  • a loudspeaker for providing an output signal;

    first and second microphones located adjacent to the loudspeaker, the second microphone positioned on a side of the loudspeaker opposite the first microphone, the first and second microphones positioned for receiving in-phase direct path echo components of the output signal; and

    an in-phase signal cancellation circuit having input terminals coupled to the first and second microphones, for combining with opposite polarity the in-phase direct-path echo components of the output signal in order to cancel the in-phase direct-path echo components.

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