1-4hit |
Some statistical analyses of modulo-2 added binary sequences are generalized to modulo-p added p-ary sequences. First, we theoretically evaluate statistics of sequences obtained by modulo-p addition of two general p-ary random variables. Next, we consider statistics of modulo-p added chaotic p-ary sequences generated by a class of one-dimensional chaotic maps.
Estimating the parameters of a statistical distribution from measured sample values forms an essential part of many signal processing tasks. K-distribution has been proven to be an appropriate model for characterising the amplitude of sea clutter. In this paper, a new method for estimating the parameters of K-Distribution is proposed. The method greatly lowers the computational requirement and variance of parameter estimates when compared with the existing non-maximum likelihood methods.
Seisuke FUKUDA Motoshi BABA Haruto HIROSAWA
Speckle statistically brings series connections of dark pixels, which can be observed as dark line features in synthetic aperture radar (SAR) images. The dark lines have no physical meaning. In this paper, line features of that kind in high-resolution SAR images whose intensity obeys a K-distribution are studied. It is stochastically explained that the dark line features in 1-look K-distributed images can be observed more distinctly than those in exponential distributed images. It is further revealed that such line features are detectable enough, even if the K-distributed images are multilooked. The experiments on simulated images as well as on actual SAR images confirm the explanation.
In order to observe temporal distribution of sea clutter, radar echoes were taken from high sea state 7 at a fixed azimuth angle of 317. It is shown that the sea-clutter amplitudes obey the Weibull distribution at a grazing angle of 3.9, and obey both the Weibull distribution and K-distribution at grazing angles of 7.5 and 61.4. As the grazing angle increases, the shape parameters of Weibull distribution and K-distribution increase with both the distributions themselves tending to be closer to the Rayleigh distribution.