Research On Positioning Calculation Technology Of Loran C Receiver

Global Navigation Satellite System(GNSS)is the most commonly used navigation timing system,but its weak signal strength leads to certain vulnerability and limitation of the system.Loran C land-based long-wave navigation timing system is considered as the most suitable backup system for GNSS.Researching the positioning principle and method of Loran C receiver to improve the timing and positioning accuracy is an important research direction for Loran C systems.In this paper,we focus on Loran C positioning algorithm and improve the accuracy of Loran C positioning algorithm in terms of improving the accuracy of geodesic distance algorithm.This paper first introduces three geodesic distance algorithms,which are the classical AndoyerLambert formula,and the high-precision developed sectional ellipse method and developed nested coefficient method for high accuracy.Subsequently,the hyperbolic single station-chain method is implemented.Cause the actual positioning area is very limited due to the limitation of the single station-chain method by the distribution of Loran C stations.To solve this problem,the hyperbolic multiple station-chains method is introduced.The multiple station-chains method uses the Geometric Dilution of Precision(GDOP)value to preferentially select two suitable hyperbolic position lines for positioning,at which point the multiple station-chains method is converted into the double station-chains method.Simulation and analysis of the accuracy of single station-chain and double station-chains method and the influence of different geodesic distance algorithms on positioning accuracy shows that under the same test conditions,the positioning error of the double station-chains method is smaller than that of the single station-chain method;the higher the accuracy of the geodesic distance algorithm is,the higher the positioning accuracy of the final positioning results is.Then,in order to further break the constraints of the positioning algorithm by the layout of Loran C stations and expand the positioning range,the circle-circle(pseudo ranges)positioning method was introduced.The simulation and analysis of the accuracy of the circle-circle(pseudo ranges)positioning method and the influence of different geodesic distance algorithms on the positioning accuracy shows that:under the same test conditions,the higher the accuracy of the geodesic distance algorithm is,the higher the positioning accuracy of the final positioning results is;when using the high-precision geodesic distance algorithm,the positioning accuracy of the circlecircle(pseudo ranges)positioning is slightly higher than that of the hyperbolic positioning algorithm.Moreover,the GDOP values of China’s Loran C chains under the hyperbolic positioning and circlecircle(pseudo ranges)positioning method are simulated with the china’s south sea chain as an example.Among them,the GDOP is an important index to measure the geometric positioning accuracy of the position line of the navigation timing system.In this paper,a high-precision Roland C positioning algorithm is implemented,which can quickly and accurately position the receiver and meet the current demand for high-precision positioning.