MONITOR SYSTEM FOR FREQUENCY SELECTIVE FADING OF FM RADIO TRANSMISSION CIRCUIT

摘要

PURPOSE:To realize a monitor for the selective fading and then obtain the circuit switching information, by monitoring the AM component level of a dispersal signal. CONSTITUTION:At the transmission part 10, an FM modulation 102 is given to the carrier wave by the dispersal signal supplied from the signal generator 103 and the carrier wave is supplied to the transmitter 104. Thus the dispersal signal 201 is converted into the AM wave 202 containing a large amount of secondary higher harmonic component at the radio section and by the central fading of the transmission band 200. At the reception part 20, the AM component 202 is detected by the detector 110, and the detection signal is extracted through the BPF111 to be supplied to the logic circuit 112. The circuit 112 transmits an alarm for switching of the radio transmission circuits when the input signal has a higher level than the prescribed value.