Analysis of sea clutter distribution variation with Doppler using the compound k-distribution

Sea clutter is the backscattered returns received by a radar system from the sea surface. Maritime radar signal processing has the ability to partially compensate for clutter to achieve effective detection of targets on or near the sea surface. This paper investigates the fit of the compound k-distribution model to sea clutter amplitude statistics, within individual Doppler bins across the Doppler spectra. The data used was recorded with a monostatic coherent X-band radar on an airborne platform; both horizontally and vertically polarized data has been analysed. The statistics of the sea clutter distributions have been evaluated using the probabilities of false alarm (P_FA), which are the calculated from the sea clutter cumulative amplitude distributions. These curves are plotted as a function of detection threshold. K-distributions have been fitted to the P_FA of the sea clutter across the Doppler spectrum. The variation of the fitted shape parameter with Doppler bin has been used to identify the relationship between backscattered sea clutter and Doppler. The results show a clear variation with Doppler of the shape parameter obtained from the fitted distribution. The variation is also found to change with polarisation.