Abstract: Transmission lines for digital signals may include a large number--for example, several hundred--of intermediate generators. In this case, telemetering units are provided at the end points and at intermediate points, by means of which the digital telemetry signals are generated and sent over the transmission lines together with the digital information signals. In the event of interference, a problem arises, due to the fact that the telemetry signal that is needed to identify the interference is only available after a comparatively long time. Therefore, according to the invention, a method is recommended for the initial synchronization, at bit rate, of the pulse generators which generate the bit pulse in the telemetering units. The pulse generation is accomplished with a phase-control loop which generates a signal pulse with a comparatively high frequency.

Abstract: Power saving means is shown for use with a converter circuit in a telephone switching installation. The converter circuit comprises an analog-to-digital converter and a digital-to-analog converter. The voltage supply for the converter circuit is switched on only upon the appearance of analog signals to be converted into digital signals or digital signals to be converted into analog signals.

Abstract: The invention relates to a method of transmitting digital data between a digitally operating subscriber station and the subscriber concentrator of a PCM/TDM telecommunication network via a two-wire trunk line at a lesser signalling bit rate than on the TDM highways of the network. Information blocks are transmitted in both directions with at least two PCM words which correspond to successive information samplings of the digital data.