Implementation of adaptive recursive echo canceller using the TMS320C25 digital signal processor

An echo canceller using equation error has been implemented using the TMS320C25 digital signal processor. An examination of measurements of the echo path impulse response shows that echoes persist over a long duration, suggesting a pole-zero model for the echo path transfer function. This suggests a pole-zero configuration for the echo canceller, rather than a truncated impulse response. The pole-zero model results in a significant reduction in the number of coefficients due to a finite number of poles and zeros necessary to model the echo path and a high degree of cancellation, since impulse response is not truncated. Simulation results are presented. The echo signal was produced by passing a random noise signal through the analog interface board to a pole-zero bandpass filter