Cophase: An ad hoc array processor
Eric S. Posmentier, Rudolph W. Herrmann · Journal of Geophysical Research Atmospheres · 1971
An ad hoc statistic, Cophase, is introduced for use in processing data from an array of detectors sensing both a propagating signal and uncorrelated noise. Cophase is basically the normalized sum over all detector pairs and over all frequencies of the cosines of the differences between phase differences from Fourier analysis and phase differences from an assumed wave vector. The distribution of the Cophase is calculated for various signal-to-noise ratios, including zero. Several numerical experiments with synthetic signals and noise and with real data presented elsewhere show that Cophase analysis is a rapid method of detecting signals above one-fourth the noise power and of estimating signal phase velocity and direction. The most important limitations of the method are the intrinsic limitations of the array size and pattern, and of the signal duration and bandwidth, but not of the Cophase analysis per se.