Precise orbit determination for the FORMOSAT-3/COSMIC satellite mission using GPS

Hwang, Cheinway; Tseng, Tzu-Pang; Lin, Tsai-Yun; Švehla, Dražen; Schreiner, B.

doi:10.1007/s00190-008-0256-3

Cited by 50 publications

(49 citation statements)

References 15 publications

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“…This is mainly due to the fact that the quality of the GPS observations is very low compared to other missions. Additionally, the attitude determination of the Cosmic satellites is rather poor, with an accuracy of approximately 2 • (Hwang et al 2008) in each axis, and the orbits of the satellites feature a high altitude of 800 km in combination with a low inclination of 72 • .…”

Section: Other Satellite Missionsmentioning

confidence: 99%

Precise orbit determination based on raw GPS measurements

Zehentner

Mayer‐Gürr

2015

J Geod

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Precise orbit determination is an essential part of the most scientific satellite missions. Highly accurate knowledge of the satellite position is used to geolocate measurements of the onboard sensors. For applications in the field of gravity field research, the position itself can be used as observation. In this context, kinematic orbits of low earth orbiters (LEO) are widely used, because they do not include a priori information about the gravity field. The limiting factor for the achievable accuracy of the gravity field through LEO positions is the orbit accuracy. We make use of raw global positioning system (GPS) observations to estimate the kinematic satellite positions. The method is based on the principles of precise point positioning. Systematic influences are reduced by modeling and correcting for all known error sources. Remaining effects such as the ionospheric influence on the signal propagation are either unknown or not known to a sufficient level of accuracy. These effects are modeled as unknown parameters in the estimation process. The redundancy in the adjustment is reduced; however, an improvement in orbit accuracy leads to a better gravity field estimation. This paper describes our orbit determination approach and its mathematical background. Some examples of real data applications highlight the feasibility of the orbit determination method based on raw GPS measurements. Its suitability for gravity field estimation is presented in a second step. B Norbert Zehentner

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Section: Other Satellite Missionsmentioning

confidence: 99%

Precise orbit determination based on raw GPS measurements

Zehentner

Mayer‐Gürr

2015

J Geod

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“…The LEO clock errors are estimated relative to GPS time along with the LEO satellite positions and velocities within precise orbit determination (POD) data processing to maintain SI traceability (Hwang et al, 2008;Schreiner et al, 2009;Montenbruck et al, 2008;von Engeln et al, 2011). With the raw RO and ground-based GPS measurements and precise positions, velocities, and clocks of GPS and LEO satellites, the fundamental RO observable, the atmospheric excess phase (in excess to vacuum) due to propagation through the atmosphere, can be computed.…”

Section: Introductionmentioning

confidence: 99%

Analysis of GPS radio occultation data from the FORMOSAT-3/COSMIC and Metop/GRAS missions at CDAAC

et al. 2011

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Abstract. This study investigates the noise level and mission-to-mission stability of Global Positioning System (GPS) radio occultation (RO) neutral atmospheric bending angle data at the UCAR COSMIC Data Analysis and Archive Center (CDAAC). Data are used from two independently developed RO instruments currently flying in orbit on the FORMOSAT-3/COSMIC (F3C) and Metop/GRAS (GNSS Receiver for Atmospheric Sounding) missions. The F3C 50 Hz RO data are post-processed with a singledifference excess atmospheric phase algorithm, and the Metop/GRAS 50 Hz closed loop and raw sampling (downsampled from 1000 Hz to 50 Hz) data are processed with a zero-difference algorithm. The standard deviations of the F3C and Metop/GRAS bending angles from climatology between 60 and 80 km altitude from June-December 2009 are approximately 1.78 and 1.13 µrad, respectively. The F3C standard deviation reduces significantly to 1.44 µrad when single-difference processing uses GPS satellites on the same side of the spacecraft. The higher noise level for F3C bending angles can be explained by additional noise from the reference link phase data that are required with singledifference processing. The F3C and Metop/GRAS mean bending angles differences relative to climatology during the same six month period are statistically significant and have values of −0.05 and −0.02 µrad, respectively. A comparison of ∼13 500 collocated F3C and Metop/GRAS bending angle profiles over this six month period shows a similar mean difference of ∼0.02 ± 0.02 µrad between 30 and 60 km impact Correspondence to: W. Schreiner (schrein@ucar.edu) heights that is marginally significant. The observed mean difference between the F3C and Metop/GRAS bending angles of ∼0.02-0.03 µrad is quite small and illustrates the high degree of re-produceability and mission independence of the GPS RO data at high altitudes. Collocated bending angles between two F3C satellites from early in the mission differ on average by up to 0.5 % near the surface due to systematically lower signal-to-noise ratio for one of the satellites. Results from F3C and Metop/GRAS differences in the lower troposphere suggest the Metop/GRAS bending angles are negatively biased compared to F3C with a maximum of several percents near the surface in tropical regions. This bias is related to different tracking depths (deeper in F3C) and data gaps in Metop/GRAS which make it impossible to process the data from both missions in exactly the same way.

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“…These official final CODE clock products and high-rate clocks partly generated for earlier periods were used for LEO POD activities (Jäggi et al 2006;Jäggi 2007;Jäggi et al 2007) at AIUB. The CODE 30-s GPS clock corrections are also used in other GPS processing software packages for LEO POD (e.g., Montenbruck et al 2005;Kroes 2006;Van Helleputte and Visser 2008;Hwang et al 2008). …”

Section: Introductionmentioning

confidence: 99%

High-rate GPS clock corrections from CODE: support of 1 Hz applications

Bock

Dach

Jäggi

et al. 2009

J Geod

166

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GPS zero-difference applications with a sampling rate up to 1 Hz require corresponding high-rate GPS clock corrections. The determination of the clock corrections in a full network solution is a time-consuming task. The Center for Orbit Determination in Europe (CODE) has developed an efficient algorithm based on epoch-differenced phase observations, which allows to generate high-rate clock corrections within reasonably short time (<2 h) and with sufficient accuracy (on the same level as the CODE rapid or final clock corrections, respectively). The clock determination procedure at CODE and the new algorithm is described in detail. It is shown that the simplifications to speed up the processing are not causing a significant loss of accuracy for the clock corrections. The high-rate clock corrections have in essence the same quality as clock corrections determined in a full network solution. In order to support 1 Hz applications 1-s clock corrections would be needed. The computation time, even for the efficient algorithm, is not negligible, however. Therefore, we studied whether a reduced sampling is sufficient for the GPS satellite clock corrections to reach the same or only slightly inferior level of accuracy as for the full 1-s clock correction set. We show that high-rate satellite clock corrections with a spacing of 5 s may be linearly interpolated resulting in less than 2% degradation of accuracy.

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Precise orbit determination for the FORMOSAT-3/COSMIC satellite mission using GPS

Cited by 50 publications

References 15 publications

Precise orbit determination based on raw GPS measurements

Precise orbit determination based on raw GPS measurements

Analysis of GPS radio occultation data from the FORMOSAT-3/COSMIC and Metop/GRAS missions at CDAAC

High-rate GPS clock corrections from CODE: support of 1 Hz applications

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