Observation of k-distributed sea clutter via an x-band radar

Abstract

In radar signal processing, it is important to eliminate unwanted noise called clutter and to detect the desired target so that the degree of discrimination is improved. To this end, the statistical characteristics of the clutter have been investigated. In such instances, it is necessary to have a process which obtains a constant false alarm rate (CFAR). In this paper, the amplitude intensity distribution of the sea clutter measured by an X-band radar is studied quantitatively by means of the Akaike Information Criterion (AIC) under an assumption that the intensity distribution is Weibull, log-normal and K-distributions. It is confirmed that, for a high sea state with wave height of 6 to 9 m and wind velocity of 25 m/s, the sea clutter follows a log-normal distribution as a whole and a K-distribution within the antenna beamwidth. With regard to the CFAR circuit by normalization of the standard deviation which is considered effective for suppression of the clutter following a Weibull and a log-normal distribution, a CFAR processing was carried out with both Monte Carlo simulation and raw data. From the results of computer simulation, it was confirmed that the CFAR circuit is effective for suppression of clutters following a K-distribution. Also, by processing the raw data by this circuit, it was successful in correctly detecting targeted ships while the clutter was suppressed.