Device for supervising a transmultiplexer

A digital transmultiplexer for converting a signal consisting of a plurality of telephony signals in TDM-Format, into a signal consisting of the telephony signals in FDM-Format and vice versa, the transmultiplexer comprising an arithmetic unit having a first input and a first output for respectively receiving and supplying, in digital form, said signals in TDM-Format and a second input and a second output for respectively receiving and supplying, in digital form, said signals in FDM-Format, a digital generator also coupled to the first input of said arithmetic unit for generating a pilot signal having a prescribed frequency for said TDM-Format signal to be converted, and filter means coupled to the first output of said arithmetic unit for selecting a pilot signal contained in the signal at said first output for controlling the level of the received FDM-Format signals;

• wherein, to monitor the proper operation of said arithmetic unit, said transmultiplexer further comprises means coupled to said arithmetic unit for supplying the signals present at said first input, said second input and said second output of said arithmetic unit, as well as the signal present at said first output of said arithmetic unit, to said filter means, whereby said filter means select a signal component having said prescribed frequency from each of said signals supplied thereto, a plurality of detection circuits each for generating a level signal relating to each of said signal components, respectively, and for comparing said respective level signals to respective thresholds, means for coupling said filter means to said detection circuits and means for utilizing the level signals for controlling the level of multiplexed signals.