ADAPTIVE ECHO CANCELLER

摘要

PURPOSE:To shorten the production time of an echo line model and to ensure an echo cancelling effect by comparing a transmission signal and a past reception signal to prevent the discontinuation of a correcting action due to a erroneous interruption. CONSTITUTION:A present reception signal supplied through an input terminal 11 of the reception side is sent to a telephone reception terminal from the output terminal 12 of the reception side and also supplied to the 1st memory 15. A transversal filter is provided with the 1st and 2nd memories 15 and 16 and a superposition integration circuit 17. The memory 16 stores the echo line characteristic. A bidirectional call detecting circuit 20 compares the past sample reception signal with a transmission signal and decides a bidirectional call when the transmission signal is larger than the reception signal. Then the circuit 20 stops the correcting action of a correction circuit 19.