Development Of The Software Package SVM For Evaluating The Quality Of Service Provided By Wide Area Augmentation System Of GPS

GPS is a radio navigation and positioning system based on satellites. Using the navigation message broadcasted by the satellites, it provides the all-weather, continuous position, velocity and time information, Because of its high accuracy, usablencss, and its cheap receiver, (IPS is widely used in many fields such as survey, navigation, positioning, responding to the emergency, resources and environment, spacial technology, tour and entertainment etc. The WAAS is a Wide-Area Augmentation System aiming at augmenting GPS to offer more accurate measurements needed by many applications.Since the number as well as distribution of the GPS satellites, delay of the ionosphere, and visibility of the reference station to the satellites are varying with time and position of the GPS receiver, the results of the GPS positioning will vary with time and position as well. Therefore it is important to prc-cvaluate the results of the positioning at certain time in certain area beloie a positioning plan.This thesis will discuss how a software evaluating the QoStQuality of Service) of WAAS is developed. Advised by Prof. Juebang Yu and co-advised by Dr. Jianming She, the software entitled as SVM(Service Volume Model) issuccessfully implemented by the author and his classmates by using MATLAB.HIThis software has been ordered by Canadian Government already. It can be not only installed in the GPS receiver but also ran on a common PC. After addressing some details of the WAAS, this thesis focus on development of algorithms for evaluating its qualities of service. There arc many services provided by the WAAS, such as Enroute through Nonprecision Approach , Precision Approach etc, the SVM can enable users to evaluate both enroute through Nonprecision Approach and Precision Approach. However, the Nonprecision Approach mode is similar to the Precision Approach mode, then this thesis only .tudies the Precision Approach mode.The SVM is designed for American WAAS, and we have not seen analogous work reported either abroad or in China. The main contribution of the thesis can be summarized as below:1) Based on the new concepts by Dr. She, the frame of several algorithm including the probability model of availability, probability model of continuity and the integrity of the ionosphere grid point are designed .2) By using the MATLAB, all algorithms are successfully implemented, some of them are optimized by full use of the advantages of MATLAB. And to meet the requirement of the customer, Graphic User Interface together with detailed documents of the SVM are also developed.