Research On High-Speed Weak Target Detection Algorithm For Bistatic Radar

With the rapid development of science and technology,more and more high-power stealth aircraft are appearing in the modern battlefield.The high-speed movement of the aircraft and its extremely small RCS have brought a lot of pressure to the military radar defense system.In order to improve the detection ability of high-speed and weak targets,it is a very effective method to perform long-term accumulation of echo signals.This dissertation focuses on the problem of range miagration and Doppler migration caused by the long-term accumulation of echo signals,and studies the high-speed and weak target detection techniques under the bistatic radar target model.The main jobs of this thesis are as follows:1.For the bistatic radar with a uniform linear motion target,the target motion parameter will produce a second-order phase term of the echo signal.As for the reduction of echo accumulation gain caused by the second-order phase term,a long-time accumulation algorithm based on Keystone transform and square phase function parameter estimation is proposed.Firstly,the Keystone transform is performed to correct the linear range migration caused by the target speed on the slow time-distance frequency domain echo signal along the slow time domain after pulse compression.The Radon transform is used to search for the estimated value of the folding factor and compensate for the linear range migration with the compensation function under the undersampling condition.And then use the square phase function to estimate the second-order coefficient and compensate the second-order phase term of the echo signal.Finally,the Fourier transform is used to achieve coherent accumulation of the echo.The effectiveness of the proposed algorithm is verified by simulation experiments.It can be applied under a very low signal-to-noise ratio condition and reduce the computational complexity.2.For the bistatic radar with a uniformly acceleration linear motion target,a long-time accumulation algorithm based on Keystone transform and frequency domain matching filter function is proposed.Firstly,the Keystone transform is performed on the slow time-distance frequency domain echo signal along the slow time domain after pulse compression,and then the frequency domain matching filter function is constructed refer to the Doppler migration number and the target acceleration and the problem of range migration and Doppler migration in the echo will be eliminated.Finally,use the Fourier transform to achieve coherent accumulation of echoes.In addition,the detection of target echo accumulation under direct signal interference in the main channel of bistatic radar receiver station is also studied.The extensive cancellation algorithm(ECA)is proposed to implement clutter suppression.The effectiveness of the proposed algorithm is verified by simulation experiments.At the same time,the applicability and stability of the proposed algorithm under the condition of a very low signal-to-noise ratio are proved.3.For the bistatic radar with a changing acceleration linear motion target,a long-time accumulation algorithm based on Keystone transform and general cubic phase function method is proposed.The method first corrects range migration by Keystone transforme,and then searches folding factor by Radon transform and compensates for range migration caused by under-sampling condition.Then,the general cubic phase function method is used to estimate target acceleration,jerk and compensate high-order phase terms.Finally,the Fourier transform is used to achieve coherent accumulation of echoes.The effectiveness of the proposed algorithm is verified by simulation experiments.