Abstract: Monitoring apparatus is disclosed for monitoring the operating condition of transmission facilities of communications transmission technology, whereby signal collectors (stations) of a signal collecting device collect trouble reports acquired in monitoring the transmission. The monitoring apparatus should collect trouble reports in as economical a manner as possible and should keep further criteria for the quality of the monitored transmission devices ready for interrogation, as needed. This is achieved by a monitoring apparatus having an evalution and memory device which periodically registers measured values. The measuring device can be advantageously employed for monitoring line terminal equipment in PCM transmission facilities.

Abstract: A controllable LC oscillator has a constant inductance and a constant capacitance. In an oscillator circuit comprising a parallel resonant circuit, voltage limiting components are connected in parallel with the resonant circuit. By way of a controllable impressed current source, the starting point of voltage limitation is controlled and, hence, an alteration of the oscillator frequency is effected. In addition, a dual of the oscillator circuit is provided comprising a series resonant circuit.