Data Processing And Analysis Of GPS Control Network At The Eastern Section Of General Water Supply Line In Central Jilin

GPS control network in the eastern section is built to guarantee tunnel engineering construction of the central city water supply project water general main line. The network was initially surveyed in September 2013 and done again in May 2014.The engineering purpose is to obtain reliable results of control points. The main research methods and contents include the data processing procedure and method of GPS control network by using LGO+COSAGPS; the hypothesis test is used to detect the systematic error of the two observation results; double observation and multi-method detection of control points are stable and unstable; the best compensation elevation surface is selected by use of least squares principle. The following results are obtained:(1) There is significant systematic error between the final two-phase plane coordinate results when the three-dimensional adjustment adopts the unconstrained adjustment. The average value is -0.98cm in the X direction and -1.08 cm in the Y;(2) The control point Z25 is unstable, measuring point difference 3.84cm;(3) The average difference is 5.77cm when two-phase control point of the geodetic adjustment results were compared;(4) The best counter height as 225m that meet?2.5 cm/km comprehensive measuring length projection deformation.The conclusions are followed:(1) The two observations should have the same reference in order to avoid the systematic error of the results of the two-period observation adjustment;(2) A variety of methods should be adopted synthetically when using double observation to check the stability of control points. Point error and distance comparison methods are relatively simple and reliable methods;(3) The control network length projection deformation can be resolved effectively by using the least square method to calculate the best part of the surveyed area level surface, which method is scientific and practical.