Abstract: An installation for transmitting telephone signals or data with time multiplexing for a plurality of subscriber sets divided into a number of groups. At least one pair of multiplexing gates actuated in synchronism are employed for each group, one for transmission and the other for reception. There is included at least one time multiplex connection, and at least one pair of first supplementary gates, respectively inserted between the multiplex connection and the transmission and reception gates connected to the subscriber sets in each single group. The first supplementary gates are actuated in synchronism with the corresponding transmission and reception gates. In the event of a fault in the transmission gate or reception gate connected to a subscriber set, the corresponding first supplementary gate is kept closed for the duration of the fault, thereby isolating the group; the remainder of the system is permitted to operate.

Abstract: The present invention relates to an apparatus for transmitting and receiving coded telephone pulses. This apparatus includes a modulation channel and a demodulation channel which are connected to a telephone instrument via a subscriber line and a duplexer, including an operational amplifier, for separating the transmitted and received signals. The demodulation channel of this apparatus comprises a demodulator whose output is connected to an active demodulating filter of the Sallen-Key type having a low-pass-type response curve adapted to compensate the distortion resulting from the demodulation.