GPS SINGLE POINT POSITIONING IN LOW-COST MOBILE MAPPING SYSTEMS WITH IGS PREDICTED EPHEMERIS

摘要

Although differential GPS could get relatively high precise positioning result, it has its disadvantages while implemented. A case in point is while the auto run out the valid range of the GPS base station. So GPS single point positioning has to be taken into consideration. Here we try to utilize following techniques to get a reasonable precision for GPS SPP (Single Point Positioning). 1. Using Chebishev Polynomials to get the position and velocity of GPS satellites from IGS Predicted Ephemeris (Ultra-Rapid Ephemeris). 2. Using Klobuchar Model to calculate ionospheric Refraction. 3. Using Hopfield Model to calculate tropospheric Refraction. 4. Smoothing of pseudorange with carrier phase. 5. Utilization of Kalman Filter in short period. After some experiments, we draw the conclusion that GPS SPP in low-cost MMS with IGS predicted ephemeris could get the positioning precision around 2m.