The -Distribution is an important clutter model for high-resolution radar sea clutter returns obtained at X-band. The Neyman-Pearson optimal multilook detector has been derived recently, as well as the generalised likelihood ratio test suboptimal detector. Both these detectors are dependent on the modified Bessel-function of the second kind. This paper suggests a suitable suboptimal approach, using a well-known Bessel identity, eliminating the Bessel function dependence. This produces a computationally simpler detection scheme, whose performance is analysed using clutter parameters based upon real X-band radar returns. 1. Introduction Coherent multilook radar detection is an area of much activity in radar signal processing research [1–6]. Much of the work undertaken in the literature is based upon a Neyman-Pearson likelihood detector, which requires the specification of an appropriate clutter model. Over the last three decades much focus has been on the -Distribution, which superseded the earlier Gaussian, Lognormal, Rayleigh and Weibull models [5–8]. The -Distribution was introduced to model observed features of real-sea-clutter returns. In particular, the -Distribution models fast fluctuations of sea clutter using a conditional Rayleigh distribution, while the underlying modulation is modelled through a gamma distribution. The fast fluctuations are called the speckle, while the modulation is known as the texture [7, 8]. The -Distribution, as an amplitude model, has density given by where the parameter is referred to as the -Distribution's shape parameter, while is called the scale parameter. The shape parameter governs the tail of the -Distribution's density, and it has been found that small values of ( ) represent more spiky clutter while larger values of ( ) produce backscattering that is closer to Rayleigh in distribution [9]. In order to improve the fit of the -Distribution to real data, [10] proposed a mixture distribution version of the -Distribution, known as the -Distribution. In this mixture model, two -Distributions share the same shape parameter , but have different scale parameters and . Its density, again in the amplitude domain, is given by the mixture where each is a -Distribution with parameters as specified. The first -Distribution density in (2) represents the Bragg and whitecap scatterers in the model. The second -Distribution in (2) represents the spike component of the clutter. Parameter is called the mixing coefficient. Comparison of this model to high-resolution radar sea clutter has been recorded in [10], where it is shown that
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