Quantitative Research on GPS Positioning in an East-North-Up Coordinate System

As the basic function of GPS, positioning has been studied extensively. However, the quantitative analysis of GPS position errors using pseudoranges is still not accurate enough. Therefore, in this paper, GPS position errors are further analysed in an East-North-Up local topocentric coordinate system. If all visible satellites are used for positioning, the expressions for GPS position errors are significantly improved by setting corresponding parameters for different latitudes. On this basis, the interrelationships between various position errors are established. If the standard deviation of a user's pseudorange error σ
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is known, the standard deviations of GPS position errors can be estimated more accurately according to the proposed formulas. The accuracy of the proposed formulas is verified using a SPIRENT satellite signal simulator, which generates realistic satellite signals at the equator, 45q north latitude and the North Pole respectively.