Orbit determination strategy using single-frequency global-positioning-system data

Orbit determination results are presented for a low-Earth-orbiter (LEO) satellite carrying a single-frequency global-positioning-system (GPS) receiver. Various techniques to correct for errors induced by ionospheric refraction are compared. These include the Jet Propulsion Laboratory's (JPL) global ionosphere maps (GIM), which provide global maps of total electron content. The direct-calibration method, differenced range versus integrated Doppler (DRVID), which uses range differences of group delay and phase advance to compensate for the first-order ionospheric error, was also tested. The fidelity of the orbit solutions was compared using orbit overlaps and or- bit differences from dual-frequency truth orbits computed using MicroCosm and JPUs Gipsy-Oasis-II program. Analyses showed that, with a single-frequency GPS receiver on the LEO satellite, the DRVID-corrected carrier phase can determine the orbit with accuracy below the meter level. JPL`s GIM correction to pseudorange data also provided improved results over no ionospheric error correction.