SYSTEM FOR PREVENTING INTERFERENCE WAVE

PURPOSE:To prevent automatically the reception of an interference wave by detecting a rapid change of a desired wave reception electric field so as to switch a reception thereby closing a signal path when the desired wave is interrupted. CONSTITUTION:A signal extracted from a reception input level monitor terminal 7 of an intermediate frequency amplifier 2 is inputted to a differentiation circuit 5, which outputs a prescribed signal only when a rapid change in the level of the input signal is detected. A switch control circuit 6 uses an output signal of the differentiation circuit 5 to control the switching of the switch 5 and detect a rapid drop of the reception input level thereby interrupting immediately the reception circuit and stopping the signal output and to detect rapid increase in the reception input level after than thereby restoring the reception circuit.