Pulse train generation appts - produces frequency which corresponds to sum or difference of frequencies of two A.C. voltages

摘要

At first the shape of the two A.C. voltage waveforms is triangular with equal slopes of rising and falling flanks, and with equal amplitudes; then a first pulse train is derived, which shows which of the two voltages is more positive at a certain time. A second and a third pulse train are generated, which show whether the slope of the A.C. voltages is positive or negative at the above instant. The three pulse trains are then logically combined into a pulse train whose frequency is the sum or the difference of the above frequencies.