| The Beidou Satellite Navigation System(BDS)has been widely used in national core infrastructure,but it is very susceptible to interference during transmission,propagation and reception due to its own characteristics and complex electromagnetic environment.Therefore,it is of great significance to study the interference monitoring technology of the Beidou system.Interference detection is the premise of interference monitoring.On the basis of studying the influence of typical interference signals and interference on signal reception performance,an improved detection scheme is proposed for the Beidou civil signal interference detection problem.The specific work is as follows:On the one hand,the interference received by the Beidou signal during transmission is classified according to the source of the interference signal and the characteristics of the interference signal.Typical interferences such as single-frequency interference,multi-tone interference,narrow-band interference,and wideband interference are modeled and simulated.The performance characteristics of these kinds of interference in power spectrum,eye diagram and constellation are analyzed.The receiving performance of Beidou signal includes acquisition performance,carrier tracking performance,code tracking performance and data demodulation performance according to the working principle of Beidou receiver.Based on equivalent carrier-to-noise ratio,a method to evaluate the reception performance of Beidou signal is presented,the influence of interference on reception performance of Beidou signal is studied,the relationship between the relevant evaluation parameters and the equivalent carrier-to-noise ratio and its calculation method is analyzed.Finally,through MATLAB simulation,the relationship between the reception performance of the signal and the equivalent carrier-to-noise ratio and the pre-detection integration time are obtained.On the other hand,four kinds of algorithm interference detection algorithms,such as energy detection algorithm,continuous mean elimination algorithm(CME),forward continuous mean elimination algorithm(FCME)and FCME algorithm based on double threshold detection are analyzed,and the algorithm is improved for the interference detection of Beidou civil signal.The Beidou civil signal interference detection system was built,and the software implementation of CME,FCME and double threshold FCME algorithm detection was implemented.The actual test,using the signal source as the interference source to generate the interference signal and the actual Beidou B1 signal are superimposed before the acquisition to generate the interference data,and the interference data is used to verify the availability of the algorithm and the effectiveness of the interference detection system.Using the signal source as the interference source to generate the interference signal and the actual Beidou B1 signal are superimposed before the acquisition to generate the interference data,and the interference data is used to verify the availability of the algorithm and the effectiveness of the interference detection system.Collecting Beidou B1 signal using high-gain antenna for a long time,and its signal quality is analyzed,using interference detection system to complete interference detection. |
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