Research And Implementation Of Anti-jamming Antenna Direction Finding Technology For BeiDou Navigation

At present,the third-generation Beidou satellite navigation system(hereinafter referred to as the Beidou system)has been basically completed,and is widely used in meteorological monitoring,mapping and search and rescue,comnunication timing and other fields.In the military field,precise positioning and navigation is provided for equipment such as precision guided weapons and missiles.The complex electromagnetic environment directly affects the reliability of the Beidou system.The interference signal direction finding technology can give information such as the state and direction of the interference signal of the Beidou system,and is the key technology to improve the reliability of the Beidou system.Therefore,the research and implementation of Beidou navigation anti-jamming antenna direction finding technology has important practical value.Based on the array antenna direction finding technology,the Beidou suppression interference signal direction finding technology is studied in this paper.The main work is as follows:1.According to the classification and generation of satellite navigation interference signals,a model of suppressive interference of Beidou system is established.2.The characteristics of MVDR beamformer,multi-signal classification(MUSIC)algorithm,decoherent MUSIC algorithm and non-coherent signal subspace(ISSM)algorithm under ideal conditions are analyzed and compared,and MATLAB simulation is earied out.The simulation results show that the MUSIC and MVDR spatial spectrum direction finding algorithm not only has high precision,but also has a small amount of computation,which can be used for FPGA implementation of Beidou navigation suppression interference direction finding.3.For the non-ideal direction finding environment with amplitude and phase error of array antenna,the influence of array element mutual coupling and antenna boundary effect on MUSIC algorithm and MVDR beamformer is theoretically analyzed.A difference of amplitude and phase characteristics of Beidou anti-interference antenna is proposed.The calibration method,under the active condition,uses the 3D electromagnetic simulation software HFSS to caleulate the mutual eoupling matrix,corrects the amplitude and phase error,and carries out MATLAB simulation verification.The simulation results show that the method has a direction-finding pitch error of less than 1°.The direction-of-sight azimuth error is less than 2°,which can be used for the direction finding of the Beidou anti-jamming antenna.4.Based on the FPGA hardware platform and VHDL language,the circuit design and development of MVDR beamformer is completed,including the antenna front module,matrix calculation module(autocorrelation matrix solution,matrix inversion)and spatial spectrum construction search module.The anti-jamming antenna direction finding function is tested,and the Beidou navigation direction finding algorithm is tested.The test results show that when the azimuth error is less than 15° and the pitch angle error i5 less than 20°,the Beidou navigation direction finding algorithm ean realize the direction finding function.And the less the number of interference sources,the higher the accuracy.