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Testable echo cancelling method and device

  • US 5,008,923 A
  • Filed: 04/17/1990
  • Issued: 04/16/1991
  • Est. Priority Date: 04/19/1989
  • Status: Expired due to Term
First Claim
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1. A testable echo canceller comprising an input and an output terminals for a far-end talker signal, an input and an output terminals for near-end talker signal a memory for storing said input far-end talker signal, a tap coefficient memory for storing a tap coefficient of an echo estimator, the echo estimating means for generating a pseudo echo signal based on the contents of said far-end talker signal memory and said tap coefficient memory, a subtracter means for subtracting said psuedo echo signal from an echo signal passed through an echo path for producing a residual echo signal, a tap coefficient updating means for serially updating said tap coefficient based on said far-end talker signal and said residual echo signal, a test far-end talker signal generating means for generating a far-end talker signal used for the test, a test echo signal generating means for generating a test echo signal with a simulated echo path, a residual echo detector having an output terminal connected to said subtracter means and for detecting a residual echo signal, and a control means for controlling formation of a path for an input and output signal passed to the echo canceller and formation of a testing circuit for making sure of the function with the echo canceller itself.

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