Multi-frequency GNSS Deviation Estimation And Its Application In PPP

With the rapid development of communication technology and aircraft technology,satellite navigation and positioning technology has been widely used in every scene of life.At present,all countries are developing their own navigation systems,and many scholars have carried out research on the Global navigation satellite system(GNSS).With the Bei Dou Navigation Satellite System,Galileo satellite navigation system and other satellite systems,and the modernization and upgrading of the Global Positioning System,Multi-frequency and multi-system integration of precision positioning has become the development trend of GNSS.It is necessary to deal with a large number of error factors in the original observation value when calculating the satellite position,which can usually be corrected by using the error file published by the data center.However,the error products published by each analysis center are different at present.In addition,some types of error product files only provide partial information of the satellite to the user,supporting the situation that the number of satellites is small.Therefore,it is of great significance to study the deviation estimation in GNSS and its application in positioning.The main research contents and work results are as follows :(1)In view of the current research on Inter-system bias(ISB)in multi-system combination,three different ISB stochastic models are used in this paper: Time constant(TC),Random walk(RT),and White noise(WN),Wuhan University,Helmholtz-Centre Potsdam-German Research Centre for Geosciences(GFZ),European Space Agency(ESA)and other sophisticated products provided by analysis centers to study the characteristics of ISB parameters between GPS/GLONASS.The results show that the ISB single-day solutions obtained by using different analysis center products have similar variation trend,but the single-day solution values are different.The single-day ISB solutions of the three random models are consistent when the same mechanism product is used.The research on the difference between ISB parameters and hardware found that the ISB value is related to the receiver antenna type,independent of other factors,and found that the size of ISB value is related to the number of satellites between systems.At the same time,the multi-day results were statistically analyzed and the effects of different strategies of different precision products on PPP accuracy were analyzed.(2)In order to solve the Differential Code Bias(DCB)between different signals of multi-system satellites,this paper analyzes the differential code bias(DCB)of the Chinese Academy of Sciences(CAS)Deutsches Zentrum fuer Luft-und Raumfahrt(DLR)and other analysis centers,and an indirect adjustment method with constraints is constructed based on zero mean constraints.This method can estimate the DCB values of multiple frequency observations in different systems.Long period estimation of DCBS of satellite and receiver of different systems is carried out,and the estimated results are compared with products of CAS and DLR.It is found that DCBS of satellite end are mainly affected by hardware such as antenna,so the change difference is small in a short time.The DCB values of most satellites show the characteristics of cluster distribution and similar DCBS among different signal channels with the same frequency.As for receiver end DCB,it is found that the same combination of receiver end DCB with different brands of receivers have different changing trends.(3)PPP experiments on different satellite systems and multi-system combination satellites show that GPS in dynamic mode has the best positioning effect,BDS is similar to GPS and performs well in the Asian region,and BDS in static mode has the best effect.In some observation stations,Galileo had the worst positioning accuracy due to the small number of satellites in the calendar,which could not be solved effectively.The convergence time analysis of static and dynamic PPP shows that GPS convergence speed is faster.As for the multi-system combination,it is found through the experiment that the positioning accuracy and convergence time are better than the other three single systems.Figure[30] Table[17] Reference[101]...