Research On Satellite Navigation Receivers Positioning Technology Based On Elevation And Clock Bias Assisted

Availability is a satellite navigation system key performance indicators which is the percentage of continuous positioning services provided by receiver. In practical application conditions, occlusion may result satellite number insufficient four and can not to locate, weak signal environment unable to get a complete satellite signal emission time, approximate location unknown environments can not meet condition of quickly positioning, etc, all these situation will lead to a decline in the availability of receiver. Consider background that assisted navigation technology development and various auxiliary measuring devices application, in order to improve availability for the receiver, expand satellite navigation receiver positioning technology research with elevation and clock bias assistance, obtain the following results of research:(1) The traditional positioning error propagation model can not be applied to the problem, when the receiver use elevation or clock bias as auxiliary information for positioning. Proposed a new error propagation analysis model in a variety of observables conditions based on the study of assisted positioning principle. To solve this problem, this paper focuses on the basis of several emergency auxiliary positioning principles, such as three satellites combined with the elevation, three satellites combined with clock bias, two satellites combined with elevation and clock bias. Use these typical occlusion environment simulation example, analysis of the distribution of positioning accuracy. The results show that new model can be used to evaluate positioning accuracy, and thus can be calculated optimal magnitude relations between pseudorange measurements and other auxiliary information, which could guide the design and selection for external auxiliary devices.(2) The traditional A-GPS positioning algorithm of weak signal, exist the problem that first calculation slower because unknown receiver clock bias and need the initial conditions of local rough time. For these two problem, proposed an positioning algorithm based on BDS hybrid constellation. Algorithm proposed use one condition that IGSO, GEO satellites in BDS has relative low dynamic to MEO satellites in GPS, another condition that receiver has implied the Earth’s surface elevation range, Increased crude solution step which could reduce the computation of clock bias fuzzy search and improve local rough time accuracy. Algorithm performance analysis shows that in the most adverse circumstances, the new algorithm compared to the traditional algorithm, on the one hand can be reduce the the first solver computation to 45.2%, on the other hand the conditions can be rough clock accuracy requirements by the 187.5s relaxed to 1500 s.(3) For approximate location is unknown, the traditional method of assisted GPS rapid positioning inability to quickly estimate pseudorange delay, proposed a quickly positioning method based on receiver sub-millisecond time-accuracy assisted. First, proposed an algorithm of build approximate position search space based on two satellite observation data, decreased the maximum number of positions to be tested from 150 million to 400 or less. Secondly, for the problem of complicated calculation on testing a single position point by traditional method, proposed two quick search positioning method respectively, one is based on the receiver clock bias estimates, another is based on pseudorange residuals estimates. Simulation results show that these two methods, testing computation on a single position point relative to the traditional method reduced to 7.1% and 1.3%.Thesis research results have been applied to China’s own satellite navigation system developed various types of receivers and other related projects.