Abstract: A digital noise blanking circuit for use in generating a single output pulse in response to a noisy signal which may include clusters of noise-induced pulses, the circuit utilizing a digital counter which is operated for a preset period of time longer than the time during which noise-induced transitional pulses may occur.

Abstract: A digital tone decoder includes means for generating a timing signal, zero crossing counter means for generating a decode signal after a predetermined number of zero crossings in response to an incoming time domain signal and for generating a reset signal at a predetermined time after the decode signal is sent to reset said zero crossing counter means to zero, and decoder means coupled to said zero crossing counter and to said timing means for generating an output signal at one of a plurality of output terminals corresponding to the frequency of the incoming signal upon receipt of the decode signal from said zero crossing counter means, said decoder means being reset to an initial state upon receipt of the reset signal.