Estimation of Ground Station Coordinates Using Normal Equation Stacking Method

Abstract

The estimation of ground station coordinates has been accomplished for the Galileo navigation system. In the estimation process, measured data from multiple frequencies, satellite state vectors and satellite clock errors are taken as input and produce an estimate of station coordinates parameters. The ionosphere error-free code measurement data for dual-frequency and triple-frequency are used for the estimation of ground station coordinates.  The present paper deals with the determination of station coordinates using the normal equation stacking method and solutions are found at each epoch. All possible combinations for dual-frequency and triple-frequency are analysed for the best combination for the station position estimates. Results and analysis are demonstrated using the methods described for the station’s position estimates for BRUX station for Day of Year (DOY) 283, 2021. The estimated position coordinates are compared with precise station coordinates to elucidate the accuracy. The maximum accuracy achieved for the position estimates is 69 cm. It has been found that (E1, E5ab) is best among dual-frequency combinations and (E1, E5b, E5ab) is best among all frequency combinations. The use of triple frequency and normal equation stacking method improves the station’s position estimates compare to dual-frequency. Results demonstrate the use of the Normal equation stacking method for coordinate estimates.