Abstract: A system for use especially by the infirm or elderly for summoning the help of others who are located a distance away. The system includes a radio-type transmitter adapted to be carried in a pocket of the elderly person, and a receiver/decoder and signalling device located at an adjoining area from which signals for help or assistance can be readily observed. The transmitter unit can be activated by means of a switch or button, and emits short bursts of a modulated signal having a unique, preselected frequency. The signal is picked up by the receiver and demodulated by a detector. The decoder comprises a sensing circuit, including a gated, resettable counter which measures the frequency of the detected signal. Means connected with the counter output trigger an alarm when the transmitted frequency having the proper modulating signal is received.