The Research And Application Of Several Problems On High-precision GPS Control And Measuring In The Field Of The Passenger Dedicated Line Of High-speed Railway

With the development of China’s economy, the speed of the High-speed railway construction anddevelopment is becoming more and more faster, and is becoming more convenient, cozy and safety. Inorder to protect the safety during the process of the trains at high speed, the high-speed rail must have ahigher ride and construction quality requirements comparing with the ordinary railway, so it is necessary touse the high-precision measurements to control during the process of construction and maintenance.Although the theory of GPS is maturing and the solution precision is improving, then it is able to achievemillimeter-level monitoring accuracy, there are still many issues that need further study according to theHigh Speed Passenger Railway Line project that distributed at line. In this paper, as the high-precision GPScontrol network in a certain high-speed railway passenger line for instance, discuss the principles andmethods of high-precision GPS control network deployment, and research and analysis a number of issues,then achieved the following results:1. The Gauss projection has a large projection error. Projection transformation as one degree, somepoints still can’t meet requirements of length of the deformation limit of high-speed rail point differential.Use the Mercator projection in any direction, can ensure that the length of the deformation is less than10mm/km tolerance requirements;2. Length deformation error has the relationship with the Geodetic azimuth, change the solution of theAzimuth in the original projection formula, and reduce the length of the deformation error;3. During the Baseline solution process, U direction transition is more obvious and the calculationresults are not stable enough comparing to the N, E. But the differences of the N, E, U, three baselinecomponents direction is obviously reducing and the baseline solution results is stable after theintroduction of CORS data. So during the process of the GPS control measurement, suggest to use thesurrounding CORS station data to improve the stability of the baseline solution; In the other hand, toimprove the accuracy of coordinate point solver as the CORS station as a starting point.4. To compare and analysis the influences between the number of different satellites, differentmonitoring time and different satellite elevation cut-off angle on the GPS coordinates, find out that if set abigger size satellite elevation angle may lead to the insufficient number of available satellite and reduce the reliability of solver; then if set smaller size satellite elevation angle may lead to the large multipath errorsand affect the accuracy of the solution. So it is more appropriate to set15degree.