Alerting Device and System for Abnormal Situations

摘要

A system for broadcasting an emergency warning throughout an area about a site, comprises a transsitter at the site for broadcasting an electromagnetic warning signal within a tunable bandwidth of a standard radio receiver for receiving commercial broadcasts, with the electromagnetic warning signal including commands for controlling the receiver, and a power amplifier within the transmitter whose power rating provides an effective local range of the electromagnetic warning signal about said site, and means for detecting the electromagnetic warning signal within its effective local range and in response thereto tuning the receiver to a carrier frequency of the electromagnetic warning signal.