Research And Implementation Of UAV Communication Link Detection And Follower Jamming Methods

Recently,with the rapid growth of civil UAV market,unauthorized flight of UAV has become a major threat to public security,which has been widely studied.This thesis carries out research on the UAV communication link detection and follower jamming technology and explores the countermeasures of unauthorized flight of UAV.The main work is as follows:（1）With analyzing the communication characteristics of the UAV in the noncooperative mode,this thesis designs the signal database and feature database.After analyzing a lot of UAV communication systems and obtaining parameters（frequency band,working bandwidth,modulation mode,frequency hopping set,etc.）,a UAV signal sampling scheme based on USRP is designed.By sampling and analyzing UAV signal,this thesis initially establishes the sampling signal database and the communication feature database.（2）An improved UAV communication link detection method is proposed.According to the short-term stability characteristics of the UAV signal bandwidth,the bandwidth matching method is used to estimate the length,bandwidth and the power of UAV signal frame.Using the periodicity of frequency hopping,this thesis detects whether there is a UAV.The test results based on simulated and real UAV signal show that compared with the conventional detection method,the proposed method has lower false positive rate and true negative rate.（3）An improved UAV signal follower jamming method is proposed.In the tracking part,the traditional ?-jitter based synchronization method is replaced by estimating the power change on UAV signal hopping time,which improves the robustness against noise.In the jamming part,the appropriate jamming strategy is selected according to the situation.The jamming waveform after clipping ensures the jamming effect,which effectively reduces the peak-to-average ratio of the jamming signal.Simulation results show that the proposed method can complete signal tracking at low signal-to-noise ratio.When the maximum amplitude of the jamming signal is limited to 1.7 times the average amplitude,the equivalent jamming power is only reduced by about 0.18 d B.（4）The above-mentioned UAV detection and follower jamming method is implemented and tested on a UAV countermeasure platform.The test results show that the proposed method can a)detect the UAV communication link effectively within 200meters;b)track the UAV signal within 80 meters;c)block the UAV communication link when the jamming-to-signal ratio is greater than or equal to 8.3d B.