MIXED NOISE CONTROL SYSTEM AND MIXED NOISE COUNTERMEASURE DEVICE

摘要

PROBLEM TO BE SOLVED: To suppress the mixed noises by providing a mixed noise countermeasure device on a transmission path of up signals to turn on a gate switch and to transmit the on signals only when the up signals are detected synchronously with each other. SOLUTION: A mixed noise countermeasure device including a synchronous detection control part 6 and a gate switch circuit 5 is provided on a transmission path of up signals and turns on the circuit 5 to transmit the up signals only when these signals are detected synchronously with each other. In such a constitution, the down signals sent from a center are separated by an HPF 3 of a 1st separation filter 1 and the up signals sent from a terminal device are separated by an LPF 4 of a 2nd separation filter 2 respectively. The up signals are inputted to the circuit 5 and the part 6. The circuit 5 serves as a high frequency switch circuit consisting of a transistor, a diode, etc., and the ON/OFF states of the circuit 5 is controlled by the part 6 and the up signals are blocked when the circuit 5 is turned off.