Gps Global Positioning System Highway Route Control Survey

This paper is concerned on a part of the research project of application of the GPS (Global Positioning system) in highway survey and design. The main content is how to use the GPS in highway control surveying and to control errors of the GPS receiver in the highway surveying for improving accuracy of position answer. The paper presents the compositions of the GPS, the principles of CIA and P code positioning and carrier phase measurement. It analyses position errors of the GPS. And detailed studies the compositions, the functions and the position algorithm of NGS-200 GPS receivers. It discussed technical design of GPS net, principles of selection control points, methods of test of the GPS receiver and judgment positioning data of the GPS in highway control surveying. The paper also deduces the mathematics model to estimate the position accuracy of the NGS-200 GPS Receivers and to use the fuzzy comprehensive evaluation according to the PDOP and the SNR (Signal-to-noise ratio) to solve the surveying position answer.