Research On Anti-jamming Of BDS/IMU Micro-system Based On Information Fusion Technology

The Beidou satellite navigation signal is usually submerged in noise by 20～30d B.It uses code division multiple access technology to modulate the navigation signal,although it has a relatively large gain.However,under strong interference or low signal-to-noise ratio,the receiver cannot demodulate the correct navigation satellite signal.When the traditional Beidou satellite navigation receiver encounters a suppressed interference signal with an interference signal ratio of more than 40 d B,it will not be able to capture the satellite signal because the signal-to-noise ratio is too low,and cannot demodulate the navigation satellite message.Therefore,information such as the almanac and orbit parameters of the satellite cannot be obtained,resulting in the satellite positioning cannot be realized.At present,inertial navigation and Beidou navigation have become standard configurations of navigation systems.Information fusion anti-jamming can utilize existing resources and achieve high anti-jamming performance without increasing system complexity.Starting from the Beidou signal processing process,the thesis conducts the following research on the information fusion anti-jamming method in the signal acquisition and tracking process and the new problems introduced in the realization of the micro system.1.Aiming at the many limitations of the current single type of anti-jamming methods such as array antenna and inertial guidance assistance in applications,an anti-jamming method that combines the signal regime and user terminal technology is proposed.The paper breaks the barriers between different types of anti-jamming methods,analyzes the anti-jamming characteristics included in the design of Bei Dou satellite navigation signal regime,and puts forward the argument of returning the anti-jamming algorithm to the satellite navigation signal regime itself.And based on the mainstream signal processing algorithms in Bei Dou user terminals,the architecture of existing signal processing is optimized through simpler external auxiliary structures to obtain higher anti-interference performance and a more streamlined anti-interference reception system.The research in this paper takes full advantage of the anti-jamming Bei Dou satellite navigation signal system and concludes that the satellite navigation system has a large potential for anti-jamming.2.For the problem that the traditional capture methods do not easily converge simultaneously in carrier frequency,code phase,bit synchronization,and frame synchronization under the interference environment,the paper proposes a multidimensional capture method based on the bulk correlator algorithm.The Bei Dou/inertial guidance microsystem takes the initial position of the carrier as well as the satellite ephemeris,fuses the acceleration and angular velocity information assisted by the inertial guidance,and performs the compensation of satellite radial Doppler during the bulk correlator capture to achieve a long-time coherent integration and suppress the interference.In addition,four dimensions of carrier frequency,code phase,navigation message and navigation message bit edge are searched to achieve multi-dimensional capture of the current two systems of Bei Dou satellite signals,and specific measures are proposed to study and refine the spectrum of the bulk correlator.3.In order to address the problems of large computing power and low tracking accuracy of the traditional anti-interference vector tracking algorithm,the paper proposes to use an open-loop UKF filter instead of the traditional loop of vector Tracking pre-filter.This method can not only reduce the computing power of the vector tracking loop,but also improve the traction range and tracking accuracy under the interference environment.The paper also proposes the corresponding loop feedback method and noise covariance matrix calculation for the UKF filter and demonstrates that the UKF filter has better anti-interference performance and lower tracking error than the traditional second-order frequency-locked auxiliary third-order phase-locked loop.4.The current Bei Dou/inertial guidance microsystem requires an external array element antenna to have anti-jamming function,which leads to an oversized Bei Dou receiver system.To address this problem,the paper proposes a new structure of anti-jamming Bei Dou/inertial guidance microsystem,which can be adapted to anti-jamming single antenna.And the feasibility of this new structure is analyzed from the aspects of anti-interference algorithm operation volume,software and hardware unit performance characteristics.Based on the new structure,the functions of the big block correlator algorithm,Beidou and inertial guidance deep combined vector tracking algorithm,and navigation and positioning solution are implemented,and application-oriented system simulation is carried out to ensure that the performance of the microsystem meets expectations,and the new structure makes the Beidou satellite navigation receiving system size and power consumption more suitable for practical applications.Finally,the paper summarizes the research results,while looking forward to the next step of work to be carried out.Some of the research results of the thesis have been applied to the design demonstration,development and testing of new generation guidance and control microsystems for space applications and other projects.