Reseach On Long Time Integration For Radar High-Speed Maneuvering Target

In radar application, the long time integration method is usually adopted to increase the signal-to- noise ratio(SN R) of the target echo and thus improve the radar weak target detection performance. However, in the long time accumulation process of the high speed and maneuvering targets’ echoes, range migration(RM) and Doppler frequency spread(DFS) problems will occur, which will result in serious performance loss for the integration processing. Therefore, this thesis mainly considers and studies the long time integration methods for the high speed and maneuvering weak targets. The main jobs of this thesis are as follows:1. The long time integration method for the targets with the radial acceleration is studied. Firstly, the second order keystone transform(SK T) is conducted in the slow time domain. Then the radial acceleration is estimated by the dechirp process algorithm and the quadratic phase of target echo is compensated with the estimated value. The SKT is conducted again and then the fold factor is estimated by Radon transform. After that, the fold factor phase term is compensated. Finally, Fourier transform is conducted in the slow time domain. Simulation experiments confirm that this method can effectively achieve the coherent integration. While compared with second order Radon Fourier transform(SRFT), the blind speed sidelobes will not appear in the result of the method in this paper.2. When the radar range resolution is not high, the RM caused by the radial acceleration rate and radial acceleration can be negligible in the process of the long time integration. However, the radial acceleration rate and radial acceleration will cause the DFS during the long time integration. For the above situation, the long time integration method based on the modified KT is studied. Firstly, this method employs the modified KT to correct RM. Then the estimates of the acceleration rate and acceleration with the improved Dechirp method are utilized to compensate Doppler frequency spread(DFS). Finally, Fourier transform is conducted to integrate the target energy. Simulation results show that this method can effectively integrate target energy and the computation complexity is lower than that of GRFT and GKTGDP.3. The long time integration method based on generalized keystone transform(GKT) and RFT is studied. This method is mainly aimed at high speed maneuvering targets with a constant radial acceleration rate. Specifically, it employs GKT to correct the RM. At the same time, the target radial acceleration rate and radial acceleration are estimated and the high-order phase terms are compensated by the estimated values. Finally, the RFT algorithm is used to achieve the coherent integration. This method can avoid the influence of the Doppler freq uency fuzzy caused by the undersampling and don’t need to search the fold factor. Simulation results show that the proposed method can get the approximately accurate estimated values of the target and the computation complexity of it is less than that of GRFT algorithm.