A Study On Anti-jamming Beamforming Techniques For High Dynamic Platform

As an important part of array signal processing,beamforming technology has been widely used in radar,sonar,communication,seismology,biological medicine,GPS,etc.Ideally,beamforming algorithm will directs the null of beam pattern at the interference,and achieve the purpose of anti-interference.But actually,the disturbances due to interference or change of posture of sports platform remove out of the null position which can not be effectively eliminate,and seriously affect the performance of the system.In addition,in actual projects,because of the external environment and processing technology,the amplitude and phase characteristics of the channels are not consistent with each other.The differences among the frequency responses of the channels are called channel mismatch.Channel mismatch will also affect the anti-jamming performance of the beamformer.To solve the above problems,this thesis studies on anti-interference beamforming technology of the high dynamic platform.And mainly completes the following work:On the basis of established the channel mismatch model,the influence of channel mismatch beamforming is analyzed.Specifically,the beamforming pattern of the array and the output signal to interference and noise ratio are affected by channel mismatch.For channel mismatch problem,an weighted frequency domain fitting channel equalization algorithm is studied.The algorithm measures the frequency response characteristic of the discrete single-point frequency of the channel,then fits the frequency response in the whole bandwidth of the channel according to the measured result,and obtains the equalizer coefficient of the channel equalizer.The algorithm can effectively avoid the problem that the divisor is zero or minimum.Simulations verify that the algorithm can well balance the frequency domain characteristics in the channel.Based on the establishment of a high dynamic array signal model,the influence of the high dynamic platform on the array signal processing is analyzed.In order to the problem that the projection technology is based on correct array steering vectors,a robust null broadening beamforming algorithm is studied.The steering vectors of array were calibrated through quadratic optimization.And then,combined with covariance matrix taper and projection transform methods,by which the sample covariance matrix of array was modified.The simulation results show that the algorithm can effectively improve the robustness to the array calibration errors and obtain broad nulls and good performance.Based on TMS320C6678 hardware processing platform,the implementation scheme of anti-interference algorithm of high dynamic platform is designed.The design method of the main modules of the algorithm is introduced in detail,and the main module is analyzed and verified.The test shows that the anti-interference module can effectively suppress the interference.