Study On DOA Estimation Of Coherent Signals Based On Fractional Lower-order Statistics On Real Sea Clutter Data

With the development of science and technology,the torpedo homing systems、radar communications、marine developwement and many other areas demand themore estimation accuracy of the target orientation, and mostly they are in thebackground of sea clutter. Usually,Sea clutter entrys the receiving system with theradar signal,and in this case,the radar echo from the sea surface is considered as asource of interference.Due to the sea surface are affected by many factors,such as, seawind、humidity、temperature，etc.so the sea clutter change is more complicated.Therefore, only by understanding and mastering the characteristics of sea clutter, canwe eliminate or weaken the effects of clutter, which also plays a vital role of thepractical application of radar. Spikes and heavy tails characteristics of sea clutter arecan be used to described by the stabilized distribution.Because there is no finitesecond moment, that is no finite variance, so the methods which are based on thetraditional second or high-order statistics are failure. To solve this problem, the atricleuse the fractional lower order statistics to study the direction of arrival estimation ofcoherent source under the noise environment of sea clutter.Firstly, we introduce the uniform line array model, and then propose a propagatormethod based on fractional low order statistics and smooth algorithm, which can beused to estimate the direction of arrival of coherent source under the sea clutter,Itavoids a large number of calculations by the eigenvalues decomposition of thecovariance matrix. Secondly,we introduce the uniform circular array model,due to thesmoothing technique is not applicable to the circular array,therefore,we propose aminimum norm method based on fractional low order statistics and the real valuealgorithm. According to property of Hermitian matrix, this method can put the plural matrix transformation into the corresponding real matrix, it reduces a large number ofcalculations by being eigenvalues decomposed in the real field.It can be used toestimate the direction of arrival of coherent source under the sea clutter. Finally, wedo some experiments on the matlab simulation platform,and then validate thealgorithm’s performance which we propose.