Research On Coherent Integration Of High-speed Weak Target Based On Keystone Transform And WNNM

In the modern battlefield environment,the stealth performance of high-speed targets is getting stronger and stronger,which also increases the detection needs for such targets day by day.This paper mainly studies the detection of high-speed targets,and analyzes the migration of high-speed targets out of a range cell.The range migration reduces the efficiency of coherent integration and decreases the accuracy of estimated the parameters of the target.In addition,the detection of weak targets is discussed.When SNR of target is extremely low,common methods-such as coherent integration and clutter suppression-can not meet the needs of targets detection in long-distance.Therefore,other algorithms are needed to improve the SNR.Since the matrix of radar echo has low rank after compensating for range migration,this paper proposes a method for radar detection of high-speed weak target based on weighted nuclear norm minimization(WNNM)algorithm.First,this paper analyzes the modeling problem of radar echoes for high-speed targets.When using narrow-band radar detect the high-speed targets,whether the reflected radar echo can satisfy the “stop-go” model is discussed,and then the speed conditions that the target needs to meet the model are given.The quantitative analysis of the range migration of high-speed targets and the influence on coherent integration is also performed.Then,for the range migration of high-speed targets,the Keystone algorithm is used to compensate.For the range migration compensation under low SNR conditions,the Keystone algorithm which is not sensitive to noise is used in this paper.The principle of Keystone algorithm is discussed and implementation is compared.For the long-distance target,there is velocity ambiguity caused by low PRF.The fuzzy number estimation is used to solve this problem.The target SNR loss caused by the inaccurate of fuzzy number estimation is quantitatively analyzed.Finally,for the problem of low SNR after coherent integration,this paper proposes the WNNM algorithm with the complex signal.The rank of radar echo matrix is analyzed;the echo matrix after the range migration compensation can use the WNNM algorithm to separate the signal from the noise.However,the existing WNNM algorithms are processed for real data such as images and videos.The radar signal is complex signal,and the coherent integration after using the WNNM algorithm also has requirement on the signal phase.In order to solve this problem,the WNNM algorithm has been modified to make it suitable for complex radar signals.For the case where the coherent integration still fails to reach the detection threshold,the proposed method can effectively improve the echo SNR of high-speed weak targets.The final simulation proves the effectiveness of the method.