A Study On Direction Finding And Positioning Technology Of Spaceborne Rotating Array

With the deep integration and rapid development of electronic technology in the field of space technology,electronic reconnaissance system has become a key way to obtain all kinds of important information.The orientation information obtained by it is invaluable in the process of reconnaissance.In the use of electronic reconnaissance system direction finding,passive direction finding localization system is becoming more and more popular because of its high concealment,wide working frequency and low complexity.The system mainly uses the interferometer direction finding system or the spatial spectrum estimation direction finding system to estimate the angle of the signal source.During the direction finding process,the interferometer direction finding system can't estimate the angle of multiple targets with the same frequency,and the system has higher requirement for signal noise ratio(SNR).The spatial spectrum estimation direction finding system can estimate the angle of multiple targets with the same frequency at the same time,but in the wide-band direction finding,the array antenna needs sparse arrangement to achieve high precision,which will cause angle ambiguity in the direction finding process.The above problems in the angle estimation are studied,and the specific work is as follows:Firstly,the situation of stationary station is analyzed.Under the premise of building multi-channel rotary interferometer,a multi-target angle estimation method based on rotating baseline is proposed.The method combines the multi-channel long baseline rotation interferometer model with the array signal processing,and the multi-target resolution is achieved by the spatial spectrum estimation.Then,according to the change rule of the angle ambiguity when the antenna rotates,the Hough transform is used to project the of all the angle estimates into the parameter space of two-dimensional angle,and the angle estimation of the signal source is obtained by the peak detection.On the basis of the proposed method,the relationship between the angle ambiguity position and the angle change of the rotary antenna is analyzed emphatically,and the angle ambiguity distribution model of the target is established.Simulation results show that the proposed algorithm can accurately extract the true angle information from multiple ambiguity angles.Then,on the basis of the proposed method,the volume constraint is added to the parameter estimation process according to the law of the ambiguity angle distribution model,which reduces the influence of the ambiguity angle to the parameter detection.Simulation results show that the performance of angle estimation algorithm is improved effectively by adding constraint conditions.For the problem that the pitch and azimuth angles of the radiation source relative to the satellite have changed during the motion because of the platform's high speed.On the premise of establishing a stationary station angle ambiguity distribution model,the angle estimation method of the satellite interferometer is analyzed and studied.Firstly,the motion model of the satellite platform is established.According to the motion state of the satellite,the variation of the signal source angle relative to the platform during the platform's motion is studied.Then the angle ambiguity distribution model under the moving platform is derived according to the angle ambiguity distribution model of the static station,and the corresponding estimation scheme of the signal source angle is also studied.The single star direction finding location algorithm is analyzed and studied.The location of signal source is realized by using the rotation interferometer location algorithm based on phase matching and the single star direction finding and positioning algorithm based on the WGS-84 earth model.The simulation results show the effectiveness of multi-target angle estimation algorithm under the moving platform.