INTERFERENCE WAVE DETECTING SYSTEM

摘要

PURPOSE:To clear the counting content of pulse signals at every specific time to evade automatically interference by detecting from a received signal that a communication signal is modulated at a carrier wave and counting pulse signals during the period other than the period during which the communication signal is modulated by using the detecting output. CONSTITUTION:A received signal from an input terminal (in) is made into pulse form at a pulsing circuit 1 and the output of the circuit 1 is inputted in one side of an AND circuit 3. A clock signal fM is inputted in one side of another AND circuit 12 and a signal indicating that a communication signal detected at a line- engagement detecting circuit 8 is modulated is inputted in the other side of the circuit 3. Outputs of the circuit 3 and 12 are respectively inputted in counters 5 and 13 and the output of the counter is inputted in an FF7. The FF7 is cleared with the output of the counter 13 and, at the same time, the output of the counter 13 is inputted in an FF14. By clearing the counter 13 by means of the FF14 and the content of the counter 5 at every specific time, the interference of an input signal is automatically evaded.