Research On Characteristics And Suppression Technology Of Sea Clutter

Sea clutter is an important factor that affects the performance of sea suface target detection radar, thus sea clutter suppression technology is a significant research topic for workers related to radar. The research on sea clutter characteristics contributes to a better understanding of sea clutter, thereby is helpful for the design scheme of the radar system and the research on sea clutter suppression algorithms. In this thesis, the research works carried out on the characteristics and suppression technologies of the sea clutter are as follows:Firstly, the sea clutter characteristics were analyzed in detail from the following aspects: how the sea clutter backscattering coefficient was in relation with the radar frequency, polarization, sea state, and the angle between the wind direction and the radar angle; temporal and spatial correlation properties of sea clutter; four kinds of statistical model of sea clutter: including Weibull distribution, Lognormal distribution,compound K distribution, generalized compound distribution, and the modeling method of each statistical distribution; non-stationary characteristics of the sea clutter amplitude and spectrum. And also each distribution model of sea clutter was simulated.Secondly, sea clutter suppression technique based on ocean dynamics was studied in detail. In this section, the inversion process of ocean dynamics parameters was elaborated, and the empirical relationship between the sea state, the sea wind speed and wave height was analyzed. Furthermore, a sea clutter method was proposed based on the sea clutter doppler frequency and spectral width which were estimated on the basis of ocean dynamics parameters. The simulation experiments using the IPIX radar sea clutter data were done and showed good results.Thirdly, the AR(Auto-Regression) model based and the SVM(Support Vector Machine) model based sea clutter suppression technology were studied. In the AR model based sea clutter suppression technology, the basic theory of AR model was introduced. The principle of the AR whitening filter to suppress sea clutter was expounded. The measured data of IPIX radar was used to realize the sea clutter cancellation, and the experiment results were analyzed. In the SVM based sea clutter suppression method, the SVM theory and the time series prediction using the SVM were elaborated. Moreover, experiments using measured data were made, thencomparison of the SVM based performance with the AR model based performance was made and the results were analyzed.Finally, the sea clutter simulator software design based on the PowerPC hardware platform was realized. The structural characteristics of PowerPC were presented, and it shows advantage in complex signal processing. The features of Tornado which is a typical embedded software development environment were described, and clutter simulation was achieved in the Tornado environment, and simulation using the prototype simulator VxSim was made. The sea clutter simulation results were showed in the end.In this thesis, the analysis of sea clutter characteristics was the basis of the research of sea clutter suppression technology. Among the three kinds of sea clutter suppression technology, the AR and the SVM based sea clutter suppression technology showed good performance, but the former can be realized more easily because of small amount of calculation. The ocean dynamics based sea clutter suppression technology provides a new idea for the sea clutter rejection method. The sea clutter simulator based on PowerPC hardware platform provides data source for the researches related to sea clutter.