Sea State Inversion And Information Processing Of HF Surface Wave Radar In Complex Environment

As a new type of ocean surveillance radar,HF surface wave radar can not only monitor the aircraft,ships and other targets in all-weather,but also retrieve the ocean parameter information according to the echo.High frequency ground wave radar detection technology has been developing since the 1970 s,and great breakthroughs have been made in the field of sea state inversion.However,due to the influence of the external environment of radar,especially the ionospheric clutter,the quality of ocean echo spectrum is reduced,which further leads to the problem of limited range and low accuracy of sea state inversion.This paper studies how to improve the sea state monitoring performance of HF ground wave radar from two aspects of ionospheric clutter suppression and sea state data processing.The specific work of the project is as follows:First,the basic structure of the ionosphere,the transmission characteristics of electromagnetic waves in the ionosphere and the influence of the ionosphere on the echo of HF surface wave radar are discussed.Based on the template detection and Otsu threshold segmentation detection methods,an adaptive template detection method is proposed to complete the detection of ionospheric clutter in range Doppler.Secondly,for the ionospheric clutter detected in the range Doppler spectrum,the clutter suppression effect evaluation method is proposed firstly,and the orthogonal projection filtering method is proposed based on the correlation of ionospheric clutter in the range domain.By analyzing the difference of energy distribution between ionospheric clutter and Bragg peak in wavelet domain,a method of ionospheric clutter suppression based on wavelet transform is proposed.Thirdly,the whole system of sea state inversion and the basis of sea state inversion are introduced,including the principle of wind wave,wave field and flow field inversion.By comparing the spectrum of ocean echo before and after ionospheric clutter suppression.On the one hand,it analyzes the change of the farthest range of radar sea state inversion,on the other hand,it analyzes the amplitude of Bragg peak,the change of energy in the first-order echo spectrum region and the second-order echo spectrum region,and the change of ocean information inversion results.Fourthly,the process of fitting ocean information into time series model is introduced.After obtaining ARIMA model,the matrix parameters of adaptive Kalman filter are derived.Using the dual frequency detection function of HF ground wave radar,a dual frequency adaptive Kalman filter algorithm based on time series is proposed to further process ocean information.Finally,the algorithm comparison is given to prove the advantages of the algorithm.