Research On Passive Location Method Of Unmanned Aerial Vehicle Target

In recent years,the unmanned aerial vehicle(UAV)industry is developing rapidly.While unmanned aerial vehicles have brought convenience to people,they have also become criminal tools of criminals.The supervision of UAV is imperative,but the premise of regulation is the ability to accurately locate the UAV which fly without permit and supervision.The method based on passive location has strong anti-interference ability,working around the clock,location of UAV and the operator before it takes off and many other advantages.First of all,this thesis studies the theory of frequency hopping communication and collects the signal(Including telecontrol signal and live view signal)of the UAV in the laboratory for analysis.And then,combined with the characteristics of UAV,this thesis studies the locating performance of UAVs in smaller areas(Generally consider a radius of 2000m)using cross-location algorithm and passive location algorithms.The premise of achieving accurate cross-location is the accurately measuring of UVA azimuth and pitch angle by direction-finding base stations.After that we can solve the plane(or space)coordinates of the UAV by the location algorithm.Next,this thesis studies the direction-finding performance of UAV in smaller areas using the amplitude search method direction finding,omnidirectional amplitude single pulse direction finding,phase interferometer direction finding,correlation interferometer direction finding and spatial spectrum direction finding,and analyzes the factors which affect the direction finding accuracy of each direction finding algorithm by simulation.After summarizing and analyzing the advantages and disadvantages of the above mentioned direction finding algorithm,this thesis proposes a method by searching amplitude ratio's table between adjacent antennas based on microstrip antenna.Then we simulate and analyze the three amplitude extraction algorithms(including FFT transforms,envelope detection,and direct averaging)to determine the optimal amplitude extraction algorithm,and verify the feasibility of the algorithm to provide a theoretical and technical preparations for engineering implementation.Finally,this thesis analyzes and simulates the two-station and multi-station crosslocation in two-dimensional plane and three-dimensional space respectively,and makes a simulation study on the factors of the positioning accuracy.This thesis also studies the fuzzy area of two-station location in two-dimensional plane and the GDOP(geometric dilution of precision)of cross positioning accuracy in two-dimensional plane and threedimensional space.After analyzing the location principle of the passive TDOA(time difference of arrival)location,this thesis analyzes and simulates the Chan localization algorithm and Taylor location algorithm to verify their ability to locate UAV.Besides,we simulate and analyze the GDOP of location accuracy in different station modes based on the Chan algorithm.At the present stage,it is difficult to guarantee the accuracy of TDOA of the UAV hopping signal,and the requirement of TDOA measurement accuracy in the small area is more demanding for TDOA location.Combined with the above research,we think that the cost of cross location is lower,the system is easier to realize,and the location accuracy is guaranteed in practical engineering now.