ECHO CANCELLATION BY CROSS-CORRELATING UP AND DOWN CHANNEL SIGNALS HAVING PREDETERMINED CHARACTERISTICS

摘要

PCT No. PCT/GB95/02618 Sec. 371 Date Jul. 2, 1997 Sec. 102(e) Date Jul. 2, 1997 PCT Filed Nov. 7, 1995 PCT Pub. No. WO96/15597 PCT Pub. Date May 23, 1996An echo detecting system includes data stores for storing signals from up and down channels respectively. The signals undergo pre-processing to identify signals forms characteristic of speech and instruct a measurement unit to carry out comparison using cross-correlation techniques between the signals stored in the stores only when such characteristics are detected. This reduces the processing power required and raises the accuracy of the correlations. Parallel processing techniques allow echoes with longer delay periods to be detected. The results of the measurement may be used to generate an echo-cancellation signal.