Resolution Measurement for Synthetic Aperture Sonar

The theoretical resolution of a Synthetic Aperture Sonar (SAS) is determined by the -3 dB beamwidth of its two-way element beampattern. In practice, resolution may be degraded by unknown factors such as imperfect estimation of the platform trajectory, seabed topography, and refractive effects due to the sound velocity profile. Methods to automatically assess the resolution practically achieved are useful for quality control and for adaptive mission planning. We show how the range-azimuth SAS point spread function can be estimated using only the autocorrelation properties of seabed reverberation. Experimental results are presented for AquaPix®, a wideband 300 kHz interferometric SAS.