Research On Key Technologies Of Single Base Station CORS In Guizhou Mountain Area

With the rapid development and wide application of GPS technology,CORS(Continuous Operating Reference Stations)technology,namely continuous operation reference station technology,has become one of the hotspots in the development of urban GPS applications.The appearance of CORS technology has changed the traditional GPS-RTK measurement mode,making the efficiency and positioning accuracy of GPS-RTK greatly improved,and the application of CORS technology is more and more widely.However,the establishment and maintenance cost of large CORS system is very high and the construction cycle is long,so it is not suitable for small and medium-sized cities and smaller units.Relatively speaking,single base station CORS is more suitable for projects with relatively long construction period and small cities(towns)because of its advantages of low construction cost,short construction cycle,mature technology,security,stability and easy upgrade and expansion,and has gained extensive attention and application.However,the terrain of Guizhou mountainous area is complex,so it is necessary to test and research the CORS of single station after completion,so that the CORS of single station can run normally in the complex terrain of Guizhou mountainous area,and improve its positioning accuracy in the complex terrain.In this paper,a series of key technologies of single base station CORS in Guizhou mountainous area are studied.The main contents are as follows:(1)The influence of the number and spatial distribution of the starting points on the accuracy of the control network is analyzed by using the results of the control network laid out to test the stability and positioning accuracy of single base station CORS.In general engineering survey control network,two starting points are sufficient to meet the plane accuracy requirements,but the elevation accuracy error is still large.In order to ensure the elevation accuracy of the control network,four elevation points should be used for elevation fitting.When the control network is laid out,the spatial distribution of the starting point and the point to be measured should be triangular as far as possible to ensure the plane accuracy,and should be evenly distributed in the control network to ensure the fitting elevation accuracy.(2)The dynamic known point detection method is used to check the stability and positioning accuracy of single base station CORS in order to ensure its normal operation in the future.The test results show that the single base station CORS has good stability and can get a fixed solution in the range of 33 km.However,when the positioning accuracy exceeds a certain range,the GPS-RTK needs to be corrected by the control point.(3)Tests show that the further the distance between mobile station and base station,the lower the accuracy of CORS of single base station.To solve this problem,this paper proposes coordinate error correction method and baseline error correction Inverse Coordinate Method to correct the positioning accuracy of CORS of single base station,and uses correlation analysis and regression analysis method in econometric geography to analyze and model the corresponding elements and get the corresponding results.The error correction model is used to improve the positioning accuracy.After correction,the plane positioning accuracy of single base station CORS has been greatly improved.The accuracy of plane coordinates of most points is improved to millimeter level,and the maximum error is not more than 2 cm.(4)To obtain the results of CORS base station positioning,this paper first uses GPS static relative positioning method to set up GPS control network to obtain the real coordinates of single base station CORS,then directly uses different combination of control points to correct GPS-RTK,and reverse calculates the results of single base station CORS coordinates.By comparing the coordinate accuracy obtained by different combination methods,we can know that three control points are calibrated.The accuracy of CORS coordinates of single base station obtained by forward and backward calculation is higher than that of base station coordinates obtained by reverse calculation of one and two points.Secondly,the accuracy of the base station coordinates obtained from the inverse calculation of the base station in the middle of the triangle formed by the three correction points is higher than that obtained from the inverse calculation of the base station coordinates outside the triangle formed by the three correction points.