Automatic emergency alarm reception apparatus using specific frequency

摘要

An automatic emergency alarm reception apparatus for a broadcasting receiver which has a radio frequency part and a low frequency part, comprising an ON/OFF switch connected between the radio frequency part and the low frequency part, for turning on the broadcasting receiver when a specific frequency signal indicative of a state of emergency is received at an antenna of the broadcasting receiver, and an emergency alarm signal detection circuit for detecting the specific frequency signal from the radio frequency part to control the ON/OFF switch. The emergency alarm signal detection circuit includes an air defense alarm signal detection part and an air-raid alarm signal detection part. The air defense alarm signal detection part is provided with a band pass filter, a level comparator, an inverter, a pulse generator and a counter. The air-raid alarm signal detection part is provided with first to third band pass filters, first to third level comparators and a sequential detector. The emergency alarm signal detection circuit further includes an OR gate for performing an OR operation with respect to an output signal from the counter and an output signal from the sequential detector, and an R-S flip-flop for controlling the ON/OFF switch in response to an output signal from the OR gate.