Velocity measurement by self-tracking correlator

Abstract

A continuously variable time delay correlator was designed for the purpose of measuring velocity. The inverse transit time (velocity) between upstream and downstream detectors is continuously adjusted by a feedback loop which maintains constant the level of cross correlation at two equal intervals from the peak correlation. Variable delay is achieved by changing the clock frequency which controls a digital shift register delay line. The output of the system is linear and identical to that calculated with parallel logic cross correlation computers.