No abstract

Korea Multi‐Purpose Satellite‐5 (KOMPSAT‐5) is the first satellite in Korea that provides 1 m resolution synthetic aperture radar (SAR) images. Precise orbit determination (POD) using a dual‐frequency IGOR receiver data is performed to conduct high‐resolution SAR images. We suggest orbit determination strategies based on a differential GPS technique. Double‐differenced phase observations are sampled every 30 seconds. A dynamic model approach using an estimation of general empirical acceleration every 6 minutes through a batch least‐squares estimator is applied. The orbit accuracy is validated using real data from GRACE and KOMPSAT‐2 as well as simulated KOMPSAT‐5 data. The POD results using GRACE satellite are adjusted through satellite laser ranging data and compared with publicly available reference orbit data. Operational orbit determination satisfies 5 m root sum square (RSS) in one sigma, and POD meets the orbit accuracy requirements of less than 20 cm and 0.003 cm/s RSS in position and velocity, respectively.

No abstract

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 orbit differences from dual-frequency truth orbits computed using MicroCosm and JPL's 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. Nomenclaturec = speed of light, m/s E LEO = elevation angle of global-positioning-system (GPS) satellites at the low-Earth-orbit (LEO) satellite position H = scale height (=100 km), m h IPP = height from ground to the ionospheric pierce point (IPP), m h LEO = altitude of the LEO satellite, m h 0 = peak point of the ionospheric density, m N = integer ambiguity P1, P2 = pseudorange observable on GPS L1 and L2 frequency, respectively r IPP = distance from the Earth center to the IPP, m r LEO = LEO satellite radial position magnitude, m s f (E LEO ) = slant function t k , t 0 = tagging time of measurement for arbitrary epoch k and minimum range epoch 0 during the phase lock, respectively, s α = scale factor ρ ion = ionospheric range delay, m λ IPP , ϕ IPP = longitude and latitude of the IPP, respectively ρ S R = geometric range from the GPS satellite transmitter to the LEO receiver antenna, m 1 = carrier phase range observable on GPS L1 frequency

No abstract