All digital phase detector and corrector

Abstract

Abstract An improved apparatus for detecting and correcting phase errors using all digital means. Transitions from a pseudo-random digital input pulse train cause a digital sample-and-hold device to store a value representing a magnitude and direction of phase error between the input pulse train and an output pulse train. This error value controls a digital pulse source whose output frequency is proportional to the error value. An up/down counter, which is incrementing at a controlled rate many times faster than the frequency of the input pulse train, is caused to increase or decrease its incrementing rate at a rate determined by the pulse source output, and in a direction determined by the direction of the phase error. A gating circuit transforms the counter contents into a value which, when sampled at the instant of transition of the input pulse train, provides a value indicative of phase error magnitude and direction to the inputs of the sample-and-hold device. The output of the highest order stage of the counter is a square wave whose phase error is continually being detected and corrected in conformity with the phase of the input pulse train.

Inventors

• 👤 Robin J Larson

Bibliographic Details