Research On GNSS Integrity Monitoring Algorithm

With the rapid development of the global satellite navigation system in the world,it has a good application in various fields.Navigation and positioning services provided by GNSS can meet the needs of most users,but in the field related to user security,especially in civil aviation,GNSS system integrity is more important than the accuracy of positioning.In this paper,a series of researches on GNSS autonomous integrity detection are carried out.The main contents are as follows:Firstly,the research background of GNSS autonomous integrity detection and the research status at home and abroad are introduced.Based on the observation model,parity vector RAIM is deduced and validated,baesd on this.he RAIM algorithm of parity vector under the small pseudorange bias is studied.It is proposed that the new detection statistics can be constructed by the non-coherent accumulation of the multi-epoch parity vector,and the RAIM algorithm is combined with the traditional parity vector RAIM algorithm,and this algorithm can have a good detection performance under slow change fault,continuous fault and mutation fault.Then,the RAIM algorithm using Kalman filter in time-domain information is studied and the two algorithms are combined.The new algorithm can detect well in the case of small stars and small pseudorange fault.Secondly,the research based on wavelet analysis integrity detection is studied,By using the multi-scale analysis in wavelet analysis and its advantages of detecting singular signals,the multi-scale decomposition of the integrity detection statistics is carried out,and the high-frequency signals are analyzed to find the system module maxima points.It makes the system in the event of a sudden failure or a small fault can detect and alert in time and improves the integrity of the sensitivity.Thirdly,Least squares RAIM model is studied based on the analysis of the parameters affecting the availability of RAIM,and the influence of the number of visible satellites,cutoff height angle,false alarm rate and missed detection rate on usability are analyzed.Then,the weighted least squares RAIM algorithm is used to improve RAIM availability.Finally,a threshold optimization method based on minimum risk cost is proposed,which realizes the dynamic optimization of the threshold and compensates for the shortcomings of fixed miss rate and false alarm rate,improves the detection rate and reduces the system risk.Finally,the ARAIM(advanced receiver autonomous integrity monitoring)algorithm is studied,and the ARAIM algorithm is put forward based on the traditional risk of integrity and the risk allocation of continuous risk.The ARAIM algorithm is optimized by Newton method,Reduces the level of vertical protection,and improves the usability of ARAIM algorithm.Simulation results show that the algorithm is feasible and correct.