Abstract: A system for providing signals to a microprocesser-based control from which instantaneous values of speed can be computed includes a wheel-driven alternator which provides an alternating current output whose frequency varies with wheel speed. A signal processor converts this signal to a series of sensor pulses whose width varies inversely with frequency. A sample pulse is supplied from the microprocessor which sets the period or length of time the sensor pulses are examined for each speed calculation of the microprocessor. The sample period pulses are AND gated with a high rate clock and also with the sensor pulses to provide a series of marker pulses marking the up and down excursions of the sensor pulses.