GDOP results in all-in-view positioning and in four optimum satellites positioning with GPS PRN codes ranging

The geometric dilution of precision (GDOP) is an indication of the quality of the GPS positioning solution when the precise of pseudo-random noise (PRN) ranging is invariable. Four Optimum satellites method is used to solve this problem in some solutions, which involve mass of calculation. In this paper, all satellites in the field of view (all-in-view) are employed to calculate the constellation's GDOP and the corresponding receiver's position error. That the GDOP of all-in-view is no more than that of the four optimum satellites is proved in theory. The experiment results show that the precise of all-in-view overmatched that of the other. Furthermore, the elevation of each satellite in view and the GPS receiver's signal to noise ratio (SNR) on satellite is introduced as fuzzy subset to weight the observation matrix when the practice environment reality, which is taken on variety and fuzzy characteristic, is considered. The experiment results indicate that the proposed algorithm is beneficial to smooth GDOP spoiled fluctuation when the constellation took place changes.