Ship echo discrimination in HF radar sea-clutter

HF radar can provide over the horizon detection of ships on very large oceanic areas. Normally, the Doppler shift produces by ships is small, of the same order of magnitude as the Doppler shift of the sea clutter. Consequently, it is not always easy to discriminate a ship line from a sea clutter line. In this paper the coherence of sea clutter is considered in the context of a radar interferometer. It is shown that the coherence function can be useful to discriminate between a ship line and sea clutter spectral peaks. The dependence of the coherence value with the signal to clutter ratio is also studied.