Measurement And Parameter Estimation Of Fragment Target In Warhead Of Large Array System

In radar high-speed weak target detection,an effective method to improve the target energy accumulation is to increase the observation time of the target.However,in the long-time accumulation process,the target often occurs the Doppler ambiguity problems of moving across range units and high-speed motion,which will affect the detection performance of the radar on the target and can not effectively achieve the target parameter estimation.Therefore,it is of great significance to study how to effectively improve the signal-to-noise ratio of radar target echo.In this paper,the key technologies involved in the multi-target resolution and high-precision measurement of warhead fragments detected by large array imaging radar are studied,and the high-speed moving target with oblique uniform velocity is taken as the research object.1.In order to obtain the target parameters of the radar transmitting field of view,the radar system adopts the small aperture antenna wide beam transmitting staring transmitting mode,and adopts the large array digital subarray phased array system to receive.The aperture of each receiving subarray matches the transmitting aperture,that is,the beamwidth of the receiving subarray is consistent with the transmitting beamwidth.After the received signals of each subarray are collected digitally,multiple near-field digital receiving beams are formed by using digital beamforming method to cover the transmitting field of view,and then all the beams are processed to obtain the target parameters in the field of view.2.Aiming at the problems of range walk and Doppler blur in the long-time accumulation process of high-speed weak target,two compensation algorithms for high-speed moving target are studied: RFT(radon Fourier transform)coherent accumulation algorithm and radon Lv's distribution algorithm These two algorithms do not need to search the velocity ambiguity factor to construct the compensation function to compensate the echo.They can directly accumulate the echo energy along the slow time dimension,and overcome the influence of Doppler frequency ambiguity.In this paper,the principles of the two algorithms are derived in detail,and the multi-target scene is verified by MATLAB simulation experiments.The simulation results show that the two algorithms can effectively improve the signal-to-noise ratio of target echo,and have better detection performance than moving target detection(MTD)algorithm in low signal-to-noise environment.3.Aiming at the mutual coupling between the target azimuth signal and the pitch signal in the large planar array antenna,the angle of the pitch dimension is measured by using the prior information of the antenna beam,and then the angle of the azimuth dimension is corrected by using the angle of the pitch dimension to remove the coupling.Then,through the radar signal processing flow,the range unit and Doppler channel of the target are measured,and then the range,azimuth,pitch angle and velocity of the target are calculated.Compared with the actual value of the target,the experimental data show that the algorithm can realize the effective estimation of the target parameters.The above work has been verified by MATLAB simulation experiments.In the near-field environment of large array,this method can effectively solve the problems of high-speed weak target moving across range units and Doppler ambiguity in the long-time accumulation process,remove the coupling of target azimuth signal and pitch signal,and improve the target detection performance of radar.