The GPS Static Data Quality Evaluation And The Stability Analysis Of The Reference Network In The Reservoir Area Of ??the Plateau Mountainous Hydropower Station

In recent years,with the increasing maturity of GPS positioning technology,the accuracy and efficiency of field data collection by GPS have been improved greatly,which has gradually replaced the traditional surveying method,and makes surveying and mapping field work depends on GPS more and more.With constantly upgrading of GPS device,GPS receivers have shifted from past single star to the current dual-band multi-satellite,and receiver data post-processing software is constantly updated.Therefore,to get higher precision results one can take advantage of different software to process data for joint solution in order to better complete survey project.In this paper,18 reference points of the GPS reference network of the Ahai Hydropower Station Reservoir together with 5 IGS stations are taken as examples.The research focuses on high-precision GPS data preprocessing,high-precision GPS baseline calculation,and high-resolution GPS network adjustment.The contents and research results can be summarized as follows:1.The principles of GPS static relative positioning,the sources of error in GPS data processing,the classification and principle of baseline calculation of GPS network,the related principles of three-dimensional unconstrained adjustment and three-dimensional unconstrained adjustment are systematically explained.2.The basic introduction and processing flow of data pre-processing software TEQC,the introduction and processing flow of high-precision GPS data processing software GAMIT / GLOBK are systematically discussed.3.Taking the GPS reference network of the Ahai Hydropower Station Reservoir as the research area,and using 4 years of GPS data,the TEQC software has been used to analyze the data quality indicators.Results of the analysis show that data quality indicators of the reference stations are all in its allowable limit of related surveying specification.RTKLIB software has been used to analyze the correlation between multipath effects,signal-to-noise ratio and satellite altitude angle.It has shown that satellite altitude angle is in negative relationship with multipath effects,and in positive relationship with signal to noise ratio.4.For the 18 reference points in the survey area together with 5 uniformly distributed IGS stations,the GAMIT baseline solution has been performed and the comparative analysis of solution accuracy has been made.5.Based on the results of the GAMIT baseline solution,through network adjustment using GLOKB,the coordinates of the reference point in each period under ITRF2008 have been calculated,and the displacement and velocity changes in X,Y,andZ directions in 4 years have been obtained,which have been compared with the displacement and velocity of LHAZ station to eliminate those that is not suitable as a reference point.