Echo canceler

  • US 6,618,479 B1
  • Filed: 09/01/1998
  • Issued: 09/09/2003
  • Est. Priority Date: 09/04/1997
  • Status: Expired due to Fees
First Claim
Patent Images

1. An echo canceler comprising:

  • (a) an echo generation circuit that (i) attenuates and delays a receive signal to obtain a delayed attenuated receive signal that constitutes a first echo component and (ii) adds the first echo component to an original transmit signal comprising a desired transmit signal and one of (i) a second echo component introduced by an external echo source and (ii) no second echo component introduced by an external echo source, to obtain a combined transmit signal; and

    (b) an echo cancel circuit that suppresses echo in said combined transmit signal and transfers the combined transmit signal having suppressed echo to an external telephone circuit by (i) generating a pseudo echo based on said receive signal and said combined transmit signal, (ii) subtracting said pseudo echo from said combined transmit signal to suppress said first echo component and said second echo component when said second echo component is present in said original transmit signal and (iii) transmitting said combined transmit signal having said pseudo echo subtracted therefrom to the external telephone circuit.

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