| In recent years,the Unmanned aerial vehicle(UAV)has developed rapidly due to the open sourcing of control system and the mature development of hardware industry.A series of functional civilian UAVs have emerged.For example,consumer-grade UAVs are popular among photographers and the general public because of its low cost,portability,easy operation,etc.Due to the expansion of UAV market,the security risks brought by "black flight" UAVs increase consequently.In response to this phenomenon,this thesis takes the DJI spirit III standard UAV and its remote-controller as the research object to study the direction finding of frequency hopping communication signal for achieve subsequent position and coercion.Firstly,the uniform five-antenna circular array of optimal direction finding is designed for the communication band of UAV and its remote-controller in this thesis.Two traditionally three-dimensional direction finding algorithms,interferometer and Multiple Signal Classification(MUSIC)algorithm,are realized by using the designed antenna array.The amplitual-phase error and position error of these two algorithms are modeled,analyzed and simulated.Moreover,amplitude-phase errors of the interferometer and MUSIC direction finding algorithms are corrected by the auxiliary source error correction algorithm and the iterative error self-correction algorithm respectively.Then,an interferometer-MUSIC joint direction finding algorithm based on two traditional direction finding algorithms is proposed.Further more,a direction finding algorithm applicable to frequency hopping signal of UAV remote-controller communication signal is proposed.Finally,a hardware platform for the uniform five-antenna circular array is built.The functions including multi-channel data acquisition,multi-channel phase consistency and direction finding algorithm are verified in this hardware platform.The key contents of the research include the following three aspects:1.A circular array of uniform five antennas is designed for the UAV communication frequency band of 2.4GHz/5.8GHz by utilizing the geometric information.It can get the best direction finding accuracy without fuzzy direction finding,and achieve the optimal direction finding.2.The performance of interferometer and MUSIC direction finding algorithms is analyzed via simulation.Combining with their advantages,an interferometer-MUSIC joint direction finding algorithm based on uniform five-circle array is proposed.The proposed algorithm achieves high-precision direction finding by searching spectral peak of MUSIC within a certain range from coarse results of the interferometer direction finding.3.A frequency-hopping signal direction finding method combining the multi-phase digital channelization technology and the interferometer-MUSIC joint direction finding algorithm is proposed for UAV remote-controller working in 5.8GHz frequency band. |
