Theresearch Of Optimization Of Solution For High Dynamic GNSS Receiver

The Global Navigation Satellite System (GNSS) aimed originally for military usage, including the positioning of marine vessels and weapons.With the constant improvement of the system and the continuation of development in receiver technology, GNSS has found usages in various fields, such as intelligent transportation, geological monitoring, or navigation of guided missile. However, the application in the field of aerospace mainly depends on the development of the technology of high dynamic receiver. Because of the highly variable speed and acceleration of a moving object,the technology of high dynamic receiver faces great challenges.Firstly,this thesis reviewed the time systems and space coordinate systems of different GNSS systems as well as the basic algorithm for positioning. As the visible satellites in a single system can be insufficient under some circumstances, the receiver tends to utilize more systems.This thesis introduces the techniques of combining different time systems and space coordinates systems, and the algorithm for fixing the position of a receiver in multimode manner. Secondly, this thesis analyzes and summarizes the error model which has large impact on the accuracy of pseudo-range measurement. Due to the low power consumption requirement of high dynamic receivers, provided the large computational work load of the usual algorithm for position fixing, this thesis adopts the Lagrange interpolation algorithm to calculate the satellite position and implements algorithm based on the circular queue. This thesis obtains the interpolation order which can satisfy the precision through the experiment.The usual least square algorithm treats all satellite measurements equally, ignoring the fact that the precision of different measurements are different. By assigning different weight to different measurement, we can improve the accuracy of results. In the fifth chapter,this thesis introduces the weighted least squares algorithm whose main target is to determine the weight of each measurement. Under single-mode, this thesis proposes an algorithm which determines the weight by combining the height angle and the normally used CNR. This algorithm first calculates the CNR and height angle based component of weights, then determines the final weight by combining them linearly. In the case of multi-mode, this thesis researches a posteriori algorithm to determine the final weight. This thesis proves that the weighted least square algorithm can produce a higher positioning accuracy than the ordinary least squares algorithm through experiments. Under the high dynamic scene, this thesis studies the Extended Kalman Filter (EKF) algorithm based on the current model,then designs the specific implementation process. Finally, this thesis summarizes the work and the deficiency in the work in the sixth chapter,and looks forward to the future work.