Research On Clutter Analysis And Suppression Technology Of Real Data In Radar

Clutter suppression technology based on the frequency domain such as MTI/MTD has been developed very mature,but the clutter characteristics in different environments vary widely,so the analysis of clutter amplitude and frequency spectrum plays an important role in the clutter suppression and target detection.On the basis of achievements obtained now,this thesis mainly studies the clutter amplitude distribution characteristics,,clutter doppler characteristics,clutter frequency estimation methods and clutter suppression methods of the real clutter data,the main contents of this thesis are as follows:1.Research on several clutter characteristics.Firstly,several basic characteristics of the clutter are introduced,including the amplitude distribution characteristics,power spectrum model and the time correlation.Secondly,the clutter characteristics of the real data are obtained by fitting the amplitude distribution characteristics and short-time power spectrum shape characteristics of different real clutter.The amplitude of the ground clutter follows Log-Normal distribution,and the amplitude of the sea clutter and rain clutter follow Log-Normal distribution.The ground clutter power spectrum conforms to the Gaussian model,while the short-time local power spectrum of the sea clutter and cloud-rain clutter can be described by two-component model.2.Research on Frequency Estimation Method of Clutter.Firstly,the clutter power spectrum estimation method of staggering PRF signal is introduced.By simulation comparison,we can see the traditional frequency estimation method can not obtain good estimation performance if related time is very short,and the iterative adaptive algorithm can approach the true power spectrum by more than 10 iterations.Then in the measured data,application of different methods is discussed through the verification and performance comparison between different frequency estimation methods.3.Research on clutter suppression method.Firstly several traditional MTI filter design methods are introduced,and the performance of several filters is compared,and the different types of clutter in the measured clutter data are analyzed and suppressed.Then, by adjusting the clutter characteristic analysis in the measured data,the adaptive filtering method is adjusted to improve the clutter suppression performance.Because the CNR is still very high outside hundreds of kilometers of the warning radar due to the atmospheric waveguide effect,high-order MTI filter is absolutely necessary to improve the clutter suppression performance.For bimodal clutter,either a cascade filter or a double-notch equivalent cascade filter is effective.If the two-mode clutter center frequency difference is not large,a wide-width single-notch filter can be used to simplify the implementation process.If the moving clutter frequency characteristics vary with distance and azimuth,multi-channel clutter suppression combined with clutter map can be used to avoid the frequency estimation error.For optimized design MTI filter,without weight calculated in real time,weight library is very useful to reduce the amount of calculation.