Coherence of pulsed signal and implications to synthetic aperture sonar processing

Previous synthetic aperture sonar (SAS) processing of low-frequency active acoustic data suggests that coherent integration apertures on the order of several thousand wavelengths can be achieved by using data-driven adaptive compensation techniques. This paper uses a normal mode based simulation to explore the interplay between adaptive compensation and medium coherence in SAS processing. Our analysis concentrates on signal fluctuations induced by background internal waves in a shallow-water region of the Mediterranean. The results indicate that commonly used adaptive compensation techniques can overcome the internal-wave-induced image smearing in azimuth. The range of internal wave spectral level tested is typical of shallow water areas