Measurement of Speed by Cross Correlation Using Pulse Frequency Signals

The transit time of a marker in a moving medium can be found by correlating the output of two transducers. A new method of determining the peak of the correlation function is described. Integral pulse frequency (IPF) signals are generated from the output of the two transducers and a binary sequence is formed. The IPF correlation function, a new approximation to the correlation function, is calculated from the binary sequence. A correlator based on the IPF correlation function has the simplicity of the polarity correlator but is sensitive to the shape of the waves being correlated. Computer simulations are presented that demonstrate the applicability of the correlator to transit time measurement.