Research On Time Synchronization Technique Of The UAV Receiving Array Radar System

As the application of UAV becomes more and more extensive,it has an irreplaceable role in modern warfare.High-precision time synchronization is one of the key technologies to realize the lightweight and collaborative work of multi-UAV formations.This thesis mainly studies the time synchronization technology of the UAV receiving array radar system from the ideal scene and the scene affected by the multipath effect.The main work is as follows:1.In the ideal scene,according to the background of the UAV receiving array radar system to which this thesis belongs,a time synchronization method via direct-path signal is proposed.First at all,the time synchronization technique via the Extended Sliding Window Accumulation method is introduced,but the time synchronization accuracy of this method can only reach the sampling period.In order to further improve the time synchronization accuracy,this thesis proposes the Extend Sliding Window Accumulation Method Combined With the MUSIC algorithm for time synchronization,which can effectively solve the situation that the time synchronization accuracy is limited by the sampling period.According to the simulation experiments,the time synchronization accuracy of the proposed algorithm is less than 1 ns under the condition of SNR = 10 d B,which meets the engineering requirements,and the time synchronization accuracy of the algorithm is significantly improved;2.In the scene affected by multipath effect,in case of few snapshots and low signalto-noise ratio,the time delay accuracy of the algorithm using the MUSIC algorithm to estimate multipath delay is not high.To solve this problem,an algorithm for estimating multipath delay using compressed sensing technique is proposed;3.In the scene affected by multipath effect,aiming at the problem that the Orthogonal Matching Pursuit algorithm and Regularized Orthogonal Matching Pursuit algorithm commonly used in compressed sensing technology are used to estimate multipath delay,it is easy to select wrong atoms and cause low accuracy,in this thesis,the Subspace Pursuit algorithm which uses the backtracking idea for the secondary selection of atoms to estimate the multipath delay is proposed.According to the simulation experiments,the accuracy of multipath delay estimation using Subspace Pursuit algorithm is obviously better than that of Orthogonal Matching Pursuit algorithm and Regularized Orthogonal Matching Pursuit algorithm;4.In the scene affected by multipath effect,aiming at the SP algorithm using the Least Squares Method to solve the least squares problem,which will use the inverse operation,resulting in high time complexity,long running time and causing space occupation by storing the matrix in the inversion operation.To solve these problems,this thesis proposes the time synchronization via Subspace Pursuit Method Combined With Conjugate Gradient Method.Based on the Subspace Pursuit algorithm,Subspace Pursuit Method Combined With Conjugate Gradient Method algorithm preferentially uses the Conjugate Gradient Method instead of the Least Squares Method to solve the least squares problem,which effectively reduces the running time of the algorithm and improves the resource utilization rate.According to the simulation experiments,under the condition of SNR=10 d B,the time synchronization accuracy of the Subspace Pursuit Method Combined With the Conjugate Gradient Method algorithm proposed in this thesis is less than 1 ns,which meets the engineering requirements.Compared with the Orthogonal Matching Pursuit algorithm,the time synchronization accuracy has been significantly improved.Meanwhile,the algorithm proposed in this thesis has strong anti-interference,good practicality and strong robustness.What’s more,the running speed of the algorithm proposed in this thesis has increased by 10.1% compared with the Subspace Pursuit algorithm.