Correlator for contactless speed measurement using 3 sensors - has extra function generator between integral regulator and voltage to frequency converter to extend range

A correlator used in the contactless measurement of speed of moving objects uses three measurement sensors. It is designed for an extended measurement range. The sensors produce signals delayed w.r.t. each other according to the time taken to traverse the distance between them. The signals are combined with time reference signals from shift registers and processed in differentiators and logic elements to produce three correlation function signals. The correlation signals are added and conducted as an input to an integral regulator which produces a signal whose frequency corresponds to the speed. To expand the measurement range a function generator is inserted between the integral regulator and the voltage-to-frequency convertor, which may be replaced by a voltage-to-period converter.