Radar characterization of ship wake signatures and ambient ocean clutter features

Characteristics of ship wakes and ambient ocean features in synthetic-aperture radar (SAR) and coherent real-aperture radar (RAR) images are studied, and two algorithms are evaluated to assess the value of using wakes for detecting and classifying ships. Empirical models of SAR ship-wake signatures, derived from measurements of wakes in L-band SAR images from SIR-B, are incorporated in the detection algorithms. To further study wake and ambient characteristics, data from a land-based X-band coherent RAR (which overlooks the ocean) are processed to obtain ocean surface Doppler velocities as a function of range and time. Line-of-sight orbital currents of ocean waves are easily detected, and the power in the velocity-field spectrum is concentrated on the dispersion curve for free-surface gravity waves. Cuts taken along this curve produce quantitative wave spectra for the study of ocean surface features and ship-induced wake modifications of the surface.<
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