CONFERENCE TELEPHONE SYSTEM

摘要

PURPOSE:To separate only a faulty channel by placing emphasis on a function fault of an echo canceller arranged to each channel and applying retraining to a fault detected at a level of each echo canceller. CONSTITUTION:An output of the echo cancellers 1-4-n-4 of each channel is subjected to time division multiplex and transmitted to a conference telephone set 2 via a transmission switch 4 as a transmission signal and also given to an echo canceller falut detecting circuit 3 at the same time. Supervisory control circuits 1-5-n-5 arranged at each channel extract an echo canceller fault detecting signal relating to the own channel, turn off the transmission switch 4 by using the signal as the start signal and a noise generator 5 is driven. The supervisory control circuits 1-5-n-5 stop a noise generating command to the noise generator 5 after a prescribed timing, an echo canceller fault detection signal is observed and when the said signal is at an L level, the transmission switch 4 is turned on.