Pseudorange Positioning And Application Of Single GPS Receiver With Single Frequency Based On Time Difference

As a new generation satellite positioning system, GPS has been widely used in all lines. Especially the GPS receiver with single frequency, because of its low cost, has been popularized rapidly. It has been increasingly widely applied in such domains as engineering geological surveying and land resource investigation, etc. As to the engineering application requiring the accuracy of meter, a single GPS receiver is used to conduct single point positioning so as to accomplish tasks quickly and efficiently. Hence, the research on single receiver with single frequency has important practical applied meaning. However, when a single GPS is used to position, particularly a single point positioning based on single frequency's pseudorange, the positioning accuracy is not exact and stable in that it is affected by satellite orbit error, satellite clock offset, tropspheric delay, ionospheric delay, multipath, geometric distribution of satellites and big noise of pseudorange. In order to improve the accuracy and stablitity of positioning with single receiver with single frequency, a systematic research on tropspheric delay, ionospheric delay, multipath and time-relative positioning based on coordination of single receiver are discussed in this thesis. The main contents of the thesis are as follows.1. It analyzes and compares the contemporary model of tropspheric delay and mapping function. A simple and practical obtaining method of the meteorologic parameter fit for GPS single point dynamic positioning is adopted and its validity in tropspheric delay computing is validated with practical data.2. It analyzes and compares the model of ionospheric delay correction fit for single point positioning with single frequency and compares the influence on the accuracy of single point postioning with IGS rapid ionospheric products and Klobuchar model, which validates that IGS rapid ionospheric products can improve the accuracy of single point pseudorange with single frequency evidently.3. On the basis of the systematic analysis of stochastic model of GPS survey, it introduces a correction method of the residual ionopspheric delay error considering the stochastic model. By the means of the analyses of experimental results with three stochastic model schemes, namely, the identical weighting stochastic model, the identical weighting stochastic model with a cut-off elevation angle, and the stochastic model based on satellite elevation, the stochastic model based on satellite elevation is more efficient to mitigate the residual errors of ionospheric delay.4. The method of single receiver time-relative positioning with loop misclosure correction is applied to the correction of the results of single point positioning with single receiver. And a positioning method of time difference on coordinate with single receiver based on loop misclosure correction is developed. The experiment validates that this method can improve the accuracy of plane grid coordinate and height efficiently.5. With the application of the positioning method of time difference on coordinate with single receiver based on loop misclosure correction to distance and area surveying, the results show that it can improve the accuracy of them.6. At last, a GPS data processing software for single point positioning with pseudorange of single frequency was developed using matlab. Combining this sofeware with the positioning method of time difference on coordinate with single receiver based on loop misclosure correction, it conducts the computing analysis of the practical experimental data, the results of which show that the accuracy and stability of positioning with pseudorange of single receiver with single frequency is improved efficiently. The results show that this method is very useful in such domains as engineering geological surveying and land resource investigation, etc.