Acoustic- Echo Cancellation Software for Hands-Free Wireless Systems
This note describes the DSP implementation of a full-duplex acoustic-echo cancellation (AEC) software. This software is based on the normalized least mean square (NLMS) algorithm. The algorithm includes active-channel and double-talk detection.
This software was implemented on a TMS320C54x digital signal processor (DSP) in assembly language. It requires few resources in terms of million instructions per second (MIPS), random-access memory (RAM), and read-only memory (ROM). AEC achieves 30 dB of attenuation in an automobile environment. The NLMS algorithm cancels more or less echo depending on the noise level, and responds well to variations of the signal level.