Algorithm Research Of GPS Long-range Network RTK Positioning

GPS network RTK is also known as multiple reference station RTK,has been widely applied in various fields as an important means in high precision and real-time dynamic GPS positioning.The correlation of satellite orbit and atmospheric delay error will reduce with thedistance between reference stations increasing,In current network RTK system,the distance between the reference station generally is range from 30 km to 80 km,which brings about high costs in base station construction and site selection problems.If the positioning accuracy is not lost,Increasing the distance between the base stations can be doubled to reduce the network RTK system construction costs.The distance between network RTK base stations is limited,resulting in high cost of building CORS system,Proposing long-range network RTK positioning algorithm.The algorithm first uses the MW combined observation equation to solve the ambiguities of the double difference wide lane of the base stations,then the Saastamoinen model and the CFA2.2 mapping function model are used to solve the dry component delay residual of double differential troposphere,and then the wet component delay residual of double differential troposphere are estimated as unknown parameters,at the same time,the ambiguities of the double difference carrier of the base stations are calculated by combining observation values without ionospheric combination;and then use the integrated error interpolation method to solve the base stations and the mobile stations error corrections;finally,using the least squares method and utilizing equation superposition by epoch to estimate the ambiguity float solution,and then utilizing the LAMBDA algorithm and the improved algorithm LAMBDA by TIKHONOV regularization to search and fix integer ambiguity resolution of wide lane and carrier,and then get the mobile station centimeter positioning results,experiments show that the algorithm can improve the distance between the base stations to 100-150km,so that mobile station users can get centimeter level positioning results.