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Adaptive dual filter echo cancellation

  • US 5,933,797 A
  • Filed: 02/28/1997
  • Issued: 08/03/1999
  • Est. Priority Date: 02/28/1997
  • Status: Expired due to Term
First Claim
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1. A dual filter echo canceller for cancelling echos in a telephony system, said dual filter echo canceller comprising:

  • an adaptive filter;

    a fixed filter coupled to said adaptive filter; and

    a digital signal processor configured to implement the adaptive filter and the fixed filter so as to process during one clock cycle an input signal sample within an adaptive dual filter echo cancellation algorithm including coefficient updating, filtering and coefficient copying between the adaptive filter and fixed filter, said digital signal processor further includes;

    a sample memory for storing the input signal sample;

    a plurality of multipliers, at least one input of each of said plurality of multipliers coupled to an output of said sample memory;

    a plurality of adders, an output of each of said plurality of multipliers coupled to at least one of said plurality of adders; and

    a plurality of temporary storage devices, an input and output of each of said plurality of temporary storage devices selectively coupled to at least one of said plurality of multipliers and said plurality of adders.

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