Performance bounds for the overlap-correlator synthetic aperture technique

Abstract

The performance bounds on a new high-performance method for passive acoustic synthetic aperture array processing are computed. The overlap-correlator synthetic aperture technique [S. Stergiopoulos and E. J. Sullivan, J. Acoust. Soc. Am. 86, 158–171 (1989)] is a method whereby the effective aperture of a towed array in the passive mode can be successfully extended. This is achieved by using the existing aperture of the physical array to estimate the phase correction factor for the successive measurement, thus eliminating the need for accurate knowledge of the source frequency when computing the phase correction factor. The performance bounds on the bearing error variance are given as a function of signal-to-noise ratio, the number of elements in the physical array, and the size and number of the overlaps. These bounds are then compared to the corresponding Cramer-Rao bounds for static line arrays and towed synthetic aperture line arrays. Results using both simulated and real data will be presented.