A Study Of Algorithms Of WADGPS Receiver Software

The technology of WADGPS can enhance the performance of GPS prominently. The information of differential correction, integrity of WADGPS and the observation of the GPS are collected together by receiver. Thus, it is an important part of WADGPS that how the receiver deals with the diversiform information to improve the positioning accuracy and ensure the integrity and availability. This dissertation mainly focuses on the algorithms of wide differential receiver software from three aspects: accuracy, integrity and availability.First of all, the basic theory of GPS positioning using pseudo-range, the dominant error sources which have an effect on the positioning and the corresponding error correction models are introduced.Secondly, three popular algorithms of navigation and positioning, which are Least Square, Kalman filtering and adaptively Kalman filtering, are introduced separately. Then their characteristics and positioning accuracy are compared with each other. Using the differential information broadcast by WADGPS, the error corrections are calculated. The interpolation algorithm of ionosphere gird is laid a strong emphasis on. The influence of using respectively or together the corrections of WAAS of a certain country on positioning accuracy is analyzed by an instance.Thirdly, the theory and means of RAIM technology is specified. Under the condition of WAAS, the algorithm of weighted RAM is discussed. After the equations of timing RAIM are derived, the correlative simulation and analysis is done.Finally, the factors which affect the availability of WAAS and their error confidence models are briefly introduced. The basic algorithm of position error protection level is presented. For the single-frequency or multiple-frequency receiver, the confidence error characteristic of the ionosphere delay estimation is analyzed. The algorithm of protection level is modified for the different cases. The regional availability of GPS/WAAS users in China is simulated and analyzed by using MATLAB. Then some valuable conclusions are put forward.