Synthetic Aperture Radar Approaches for Small Maritime Target Detection and Discrimination

Synthetic aperture radar (SAR) has the ability to detect and discriminate slow moving (= 10 knots) low radar cross section (RCS) objects such as small surface vessels and surface signatures in maritime environments at low-to-mid grazing angles. The physical mechanisms for detection and discrimination are made possible by the combination of coherent and non-coherent scatting phenomenology associated with the surface target direct and multipath interaction with clutter that is captured by the SAR imaging process. The detection and discrimination processing can be embedded in the SAR image processing by exploiting synthetic sub-apertures that can be used to construct the overall synthetic aperture coherently. It is essential to note that the synthetic aperture (or sub-aperture) process is a coherent Doppler domain process and it is in the Doppler domain where the detection and discrimination signal processing function is implemented. Unfortunately, SAR spotlight operation has very little search rate to be of practical use and SAR strip map (or push broom) operation has relatively low search rates in comparison to scanning radars. LSI recommends and proposes a research effort that evaluates the signal processing that performs the detection and discrimination using SAR strip map data and extends these capabilities for use with scanning coherent surface search mode operation for significant improvement in search rate that will also enable subsequent feature aided tracking.