Comparison of SAS processing strategies for crabbing collection geometries

This paper presents a number of different processing strategies for generating synthetic aperture sonar (SAS) imagery when data collection suffers from significant sideways crab (where we define crab as the angle difference between track and heading). Whilst large amounts of sideways crab do not present fundamental limitations to the SAS method, the assumptions SAS processing chains are built upon are often violated under such conditions. We discuss typical assumptions and compare alternate image formation strategies. We also provide a short discussion of the fundamental limitations to crabbing systems. We found that the adjustments to our standard wavenumber-based imaging kernel increased crab-tolerance from approximately 7 degrees up to approximately 30.