CIRCUIT ARRANGEMENT FOR LEVEL SUPERVISION IN TRANSMISSION SYSTEMS WITH FREQUENCY-OR PHASE MODULATION

摘要

Circuitry is described for supervising the signal levels in frequency or phase modulation transmission systems by means of an evaluation circuit which emits a first signal if a predetermined threshold level is exceeded by the carrier frequency. A second signal is emitted if the carrier frequency undershoots said threshold level. A threshold circuit recognizes when the carrier frequency exceeds the predetermined threshold level and operates to actuate a first time element which is designed to determine whether the carrier signal has failed to reach the threshold level during a specified time period.