| With the proposal of "Maritime Silk Road" and the policy of building a maritime power,radar detection technology has been applied more and more widely in military and civilian areas,and people have put forward increasingly high requirements for its detection accuracy.Sea clutter is the most important factor affecting the detection of maritime targets and the most difficult to remove,so sea clutter suppression has become the research focus in the field of radar detection.Many scholars have made a lot of research on sea clutter suppression,which makes the suppression algorithms based on different principles emerge constantly.It includes sea clutter suppression methods based on cyclic iteration cancellation,model prediction,fractal feature and subspace decomposition.Since the sea clutter suppression algorithms based on cyclic iteration cancellation,model prediction and fractal features are only applicable to clutter suppression under specific sea state situations and are not universal,this paper mainly uses the complex characteristics of sea clutter and proposes two clutter suppression algorithms under different scenarios based on the sea clutter suppression algorithm based on subspace decomposition.The specific research content is as follows:(1)To address the problem of difficult detection of fast moving target echo signals on the sea surface under the background of strong sea clutter,a sea clutter suppression algorithm combining Singular Value Decomposition(SVD)and Moving Target Indication(MTI)techniques with a dual delay line pair cancellation algorithm is proposed(abbreviated as SVDMTI algorithm).First,the pulse-compressed target echo signal are rearranged into a fast and slow time dimension matrix by period,and the period singular value decomposition is performed;then the relationship between the threshold value of the corresponding singular value and the input signal to Clutter Plus Noise Ratio(SCNR)is constructed,and the threshold value is used to judge the singular value exponential ratio to achieve adaptive distinction between the sea clutter and the target signal;finally,the reconstructed target signal is subjected to double delay line pair cancellation to suppress the clutter while ensuring the loss of the target signal is minimized.Compared with the existing sea clutter suppression algorithm,the proposed method can adapt to the change of the signal-to-noise ratio of the target echo sequence,and can still suppress most of the clutter and accurately detect the signal under the input signal-to-noise ratio of-30 d B.(2)A sea clutter suppression algorithm(PCA-SVD algorithm)combining Principal Component Analysis(PCA)algorithm and singular value decomposition algorithm is proposed to address the problem that the radar echo signals of slow and small targets on the sea surface are often drowned in strong sea clutter.Firstly,after pulse compression of the data received from the radar receiver,the echo signal is rearranged into a fast and slow time dimension matrix according to the period;then a sea clutter time correlation model is constructed and the PCA operation is performed without changing the feature dimension;finally,the PCA echo signal is decomposed into sea clutter part and signal part by period singular value decomposition,so as to remove the clutter and reconstructs the recovered signal.The algorithm ensures that the loss of the target signal is minimized while the clutter is suppressed,and the effectiveness of the proposed method is verified from theoretical derivation to experimental data. |
