Research On Algorithm Of The Clutter Suppression For High-frequance Surface Wave Radar Based On Multi-domain Analysis

In recent decades,High-Frequency Surface Wave Radar has gradually developed.As an over-the-horizon radar,it can perform target detection on new types of ocean dynamic parameters(wind,wave,and flow fields)..In view of the complex external environment of radar work,it has been subject to various restrictions in the application of actual conditions.Under the complex external environmental conditions,the performance of High-Frequency Surface Wave Radar has been severely affected,for example,the effective radar detection distance has become shorter and the quality of radar echo spectra has deteriorated,resulting in the subsequent extraction of sea state information and the detection of tracking targets becoming even more complicated.This paper will proceed from the perspective of signal processing and focus on how to improve the development of High-Frequency Surface Wave Radar.The specific work of the topic can be divided into the following few parts:Firstly,in order to suppress the Es layer ionospheric clutter and its one-hop and two-hop echoes in the echo spectrum received by radar,the topic proposes a clutter cancellation algorithm based on distance correlation.The core is to use the strong correlation of ionosphere adjacent distance elements for cancellation processing.On this basis,an improved algorithm is proposed to use the cross correlation between the Es layer ionospheric clutter and its one-hop and two-hop echoes.Second,since the nonstationarity of ionospheric clutter in the echo spectrum of waves is very strong,the effect of a single treatment method on suppressing its interference is not obvious.This topic proposes a multi-domain combined algorithm,which is based on the eigenvalue decomposition algorithm in the time-frequency domain.The basic principle is to use the eigenvalue decomposition method to process the echo signals in the pulse domain and the doppler domain respectively.Thirdly,in terms of suppressing weak ionospheric disturbances,the core of the algorithm is threshold segmentation.Using its segmentation echo data,after the segmented radar echo data,clutter detection is performed to detect the corresponding regions of the ionosphere and sea clutter,eliminating ionospheric clutter and preserving sea clutter to complete radar echo data processing for weak ionospheric clutter.Fourth,this project proposes a clutter-aware cancellation algorithm.The algorithm can automatically identify whether there is Es layer ionospheric clutter in the received radar echo signal,and achieve ionospheric clutter elimination,thereby increasing Subsequent sea state inversion accuracy.Fifth,in order to judge the effectiveness of the clutter cancellation algorithm basedon distance correlation and the eigenvalue decomposition algorithm based on time-frequency domain,the echo signals before and after the anti-jamming are subjected to the sea state inversion.The inversion is mainly aimed at the extraction of the radial velocity of the ocean current,and the performance of the algorithm is verified by comparing the extraction effects.