SYSTEM FOR REMOTE SUPERVISION OF TWO-WAY REPEATER STATIONS IN MULTICHANNEL PCM TELECOMMUNICATION PATH

A multichannel PCM telecommunication path, extending between two terminal stations, comprises a d-c service line common to m parallel channels which are divided into two groups for transmission in opposite directions. A plurality of cascaded repeating stations, with m repeaters each, are inserted in that path and are each provided with a single band-pass filter designed to pass a test frequency individual to any repeating station. The test frequency is established by an unbalanced interrogation code which is iteratively transmitted over a given channel from a control post at one terminal over an outgoing channel and returned thereto over an incoming channel in a loop closed at the other terminal in response to the code. The filtered-out test frequency can be fed to the control post via the service line from the outputs of the two repeaters in the closed loop by way of two transformers and respective diodes which are inversely biased by a d-c potential on the service line, the polarity of this potential being reversible at the control post to select either of these repeaters for testing.