Abstract: Readily available digital logical circuit components are arranged in circuitry for enhancing demodulation of frequency shifted or phase shifted modulation signals in the presence of a received carrier wave and inhibiting demodulation in the absence of any recognized carrier wave. The circuitry is arranged for measuring the time between adjacent impulses as received including noise impulses which penetrate an input band-pass filter. The preponderance of signal impulses lie within predeterminable limits, however, and the circuitry is arranged for indicating the presence of a data signal despite some noise impulses passing through the filter. The electronic circuit components are conventional and also are readily laid down in semi-conductor structures of the popular types.