LOUDSPEAKER-MICROPHONE SYSTEM WITH ECHO CANCELLATION SYSTEM AND METHOD FOR ECHO CANCELLATION

摘要

A two way sound reproduction system, such as a mobile phone system has an input (2) for an incoming far end signal (W), a loudspeaker (5), a D-to-A-converter (3) between the input (2) and the loudspeaker (5), a microphone (7), a A-to-D (8) converter after the microphone (7), an echo cancellation system (AEC) and an output (12) for an outgoing far end signal. The system comprises a pre-processor (30) between the input (2) and the D-to-A converter (3) comprising: an amplifier (32) to amplify the signal to a sufficient sound pressure level, a clipper or compressor or limiter (33) to limit the signal in the digital domain, so that the telephone system between D-to-A converter (3) and A-to-D converter (8) behaves substantially like a linear system.