Patent ID: 7693276
Filing Date: 2010-04-06
Classification: H04B

Abstract:
1. A method of determining residue-echo threshold for a trans-hybrid echo path of a loop start trunk line, comprising: estimating an impulse response of said trans-hybrid echo path; applying a plurality of test signals to said trans-hybrid echo path and storing resulting respective echo signals, the test signals comprise clipped speech signals to cause distortion in said loop start trunk line; convoluting said test signals with said impulse response resulting in a plurality of convolution results; subtracting said convolution results from said respective echo signals resulting in respective residue-echo values J storing said respective residue-echo values J determining said residue-echo threshold as a residue-echo value associated with a predetermined one of said test signals beyond which said residue-echo values remain substantially constant with increasing levels of said test signals.