Patent ID: 8619970

Claim:
A method of updating the adaptive filter of an echo canceller in which an estimated echo is resolved from a received signal and then subtracted from an incoming echo-contaminated signal so as to produce a filtered output signal, comprising: obtaining a corrected impulse response (hc) of an echo reconstruction filter (ERF) by calculating a record of an estimated echo (Ee) from the ERF using a current ERF impulse response he and a record of a reference signal X, resolving an estimate of the local signal plus noise Ve n by subtracting the estimated echo Ee from a record of an input signal Y n , estimating a residual frequency response Hr with a record of Ve and X using spectral estimates of S X and S Ve,X , and computing the corrected ERF impulse response (hc) based on the spectral estimates using the following equation: hc = he + IFFT â¡ ( S ^ Ve , X S ^ X ) ; calculating specified decision measures usable to decide whether to prospectively apply the corrected ERF impulse response hc or a current ERF impulse response he to a reference signal (X), the decision measures being (i) a mutual information rate (infoVeX) of an estimate of the signal plus noise (Ve) and the reference signal (X), (ii) an estimated echo return loss enhancement (ERLEi) of the echo canceller, and (iii) a corrected echo return loss enhancement (ERLEc) of the echo canceller; determining whether application of the corrected ERF impulse response hc would result in improved echo cancellation by (i) comparing a mutual information rate of infoVeX to a specified threshold, and (ii) comparing the ERLEc to the ERLEi; and updating the ERF to apply the corrected impulse response hc, when it is determined that the updating would result in a lower residual echo (Er).