GNSS Signal Interference And Enhancement Analysis

GNSS(Global Navigation Satellite System)has global,all-weather,all-day PNT service capabilities,but GNSS has natural vulnerabilities,and its navigation and positioning timing may be attacked or interfered with.Therefore,it is necessary to monitor and evaluate the navigation and positioning performance of the satellite navigation system.During the U.S.war against Syria in April 2018 and the U.S.conflict against Iran in June 2019,GNSS signals were subject to various degrees of interference.In order to cope with the interferences,GPS implemented satellite power enhancement.This paper mainly analyzes the performance monitoring of GNSS system under disturbance and the system performance after GPS power enhancement.The main research contents and achievements of this paper are as follows:1.Analyze the data quality of GNSS satellite navigation system from three aspects of data integrity rate,multi-path effect and signal-to-noise ratio.The analysis shows that the MEO satellites of the four systems and the IGSO satellite of the BDS system have a certain negative correlation between the multipath error and the satellite altitude angle and signal-to-noise ratio,that is,when the height angle is small or the signal-to-noise ratio is low,the change range and dispersion degree of the multipath error increase significantly,and vice versa;the GEO satellites of the BDS system,the change of multipath error shows a certain periodicity with the change of altitude angle,and when the signal-to-noise ratio changes slightly,the fluctuation range of multipath error is also small.2.Introduce the navigation signal structure of the GNSS satellite navigation system in detail,analyze the changes of the signal-to-noise ratio of the observation data of the four GNSS systems under interference,and the changes of the signal-to-noise ratio of the GPS after implementing power enhancement in response to the signal disturbance.At the same time,the analysis gives the signal power enhancement and recovery moments in the two GPS enhancement events in April 2018 and June 2019,and the changes in the signal power of the satellites at different frequency points and types.The results show that the power of GPS IIRM and GPS IIF satellites have gradually increased in the global range,and the enhancement power values of different frequency points(L1W,L2W)are equivalent,about 7 ? 10 d BHz.3.Aiming at the data related to navigation disturbance and GPS power enhancement,the thesis carried out the research on the pseudo-distance single point positioning of GNSS,and analyzed the single frequency of four single systems including GPS,BDS,Galileo and GLONASS(GPS: L1,BDS: B1,Galileo: E1 and GLONASS: G1)navigation and positioning performance,including the number of visible satellites(Number of Satellites),dilution of precision(Position Dilution of Precision)and positioning accuracy.The results show that: the GPS system is affected by interference,the positioning accuracy is low,and the positioning cannot be achieved in some periods.After the power is enhanced,the GPS positioning accuracy is improved to the normal level.Galileo system has the worst positioning accuracy during the interference period.The positioning accuracy of the BDS system in the selected station is relatively lower than that of GPS(positioning accuracy in the non-interference period);The overall positioning accuracy of GLONASS is also slightly lower than that of GPS(positioning accuracy in the non-interference period).