A system and method for correcting non-periodic event time of arrival data in a control system. The system and methods are particularly applicable to the speed and phase control of a color wheel used with spatial light modulators. The circuitry automatically and accurately compensates for non-periodic index signals occurring when one or more index marks on the color wheel are misplaced. The system adds to or subtracts clock pulses from the actual time of arrival of a specific index mark until the corrected value equals the desired or nominal value. The system then generates a PWM signal for controlling the speed and phase of the color wheel.