Two improved ping-to-ping cross-correlation methods for synthetic aperture sonar: theory and sea results

The paper reports on two improved ping-to-ping cross-correlation (P²C²) methods for synthetic aperture self-calibration: auxiliary frequencies P²C², which relies on exploiting echo signals from transmission at two additional frequencies, and hybrid P²C² which combines array processing and measurement of the array rotation by means of gyrometers. Analytical expression for the self-calibration accuracy and the maximum resolution gain show that both methods allow greater travel speed and higher resolution. They have been tested at sea on an interferometric synthetic aperture sonar dedicated to deep sea floor survey. Resolution gain values up to 50 are illustrated by some sonar images of the Mediterranean Sea floor.