Spatially Compact Clutter

Clutter false alarms plague most active sonar systems. A common source of false alarms is examined in this paper—spatially compact clutter. Echoes from a shipwreck are analyzed and found to have clutter-producing heavy-tailed probability density functions and similar statistics at both 2-km and 10-km ranges, the latter in contrast to expectations based on the different propagation conditions. The clutter model of [1] is applied to represent spatially compact clutter, illustrating that clutter objects with minimal down-range extent appear to be minimally impacted by multipath, potentially explaining the similarity observed in the real data. The theory also indicates that when the clutter source is sufficiently small and strong relative to the surrounding background, the sonar receiver statistics are largely unaffected by variations in multipath, matched filtering, and array processing.