Phase center modeling for LEO GPS receiver antennas and its impact on precise orbit determination

Zhao

et al. 2014

Sci. China Earth Sci.

The GPS, DORIS, and SLR instruments are installed on Haiyang 2A (HY2A) altimetry satellite for Precise Orbit Determination (POD). Among these instruments, the codeless GPS receiver is the state-of-art Chinese indigenous onboard receiver, and it is the first one successfully used for Low Earth Orbit (LEO) satellite. Firstly, the contribution assesses the performance of the receiver through an analysis of data integrity, numbers of all tracked and valid measurements as well as multipath errors. The receiver generally shows good performance and quality despite a few flaws. For example, L2 observations are often missing in low elevations, particularly during the ascent of GPS satellites, and the multipath errors of P1 show a slightly abnormal pattern. Secondly, the PCO (Phase Center Offset) and PCV (Phase Center Variation) of the antenna of the GPS receiver are determined in this contribution. A significant leap for Z-component of PCO up to 1.2 cm has been found on 10 October 2011. Thirdly, the obtained PCO and PCV maps are used for GPS only POD solutions. The post-fit residuals of ionosphere-free phase combinations reduce almost 50%, and the radial orbit differences with respect to CNES (Centre National d'Etudes Spatiales) Precise Orbit Ephemeris (POEs) improve about 13.9%. The orbits are validated using the SLR data, and the RMS of SLR Observed minus Computed (O-C) residuals reduces from 17.5 to 15.9 mm. These improvements are with respect to the orbits determined without PCO and PCV. Fourthly, six types of solutions are determined for HY2A satellite using different combinations of GPS, DORIS, and SLR data. Statistics of SLR O-C residuals and cross-comparison of orbits obtained in the contribution and the CNES POEs indicate that the radial accuracy of these orbits is at the 1.0 cm level for HY2A orbit solutions, which is much better than the scientific requirements of this mission. It is noticed that the GPS observations dominate the achievable accuracy of POD, and the combination of multiple types of observations can reduce orbit errors caused by data gaps and maintain more stable and continuous orbits. Haiyang 2A, GPS receiver, multipath, precise orbit determination, phase center offset, phase center variations, DORIS, SLR Citation: Guo J, Zhao Q L, Guo X, et al. 2014. Quality assessment of onboard GPS receiver and its combination with DORIS and SLR for Haiyang 2A precise orbit determination. Science China: Earth Sciences,

Section: Gps Antenna Phase Center Modelingmentioning

confidence: 99%

Quality assessment of onboard GPS receiver and its combination with DORIS and SLR for Haiyang 2A precise orbit determination

Zhao

et al. 2014

Sci. China Earth Sci.

“…Table 2 lists the coordinates for the center of the mounting plane (CMP) of the SSTI-A antenna in the SRF. Jäggi et al (2009) showed that neglected or mismodeled antenna phase center offsets (PCOs) and variations (PCVs) are important systematic error sources in GPS data processing of LEO satellites. Table 3 summarizes the PCO values for the two GPS frequencies in the antenna reference frame (ARF).…”

Section: General Information About Goce Gps Data Processingmentioning

confidence: 99%

“…The requirement in latency is 2 weeks with an accuracy of 2 cm (1D, Visser et al 2006). The two institutions have proven their ability for LEO POD in, e.g., Jäggi et al (2007Jäggi et al ( , 2009van den IJssel et al (2003); Montenbruck et al (2005Montenbruck et al ( , 2008 and have shown in Bock et al (2007) and Visser et al (2009) that the POD requirements for the GOCE mission can be met with their procedures.…”

Section: Introductionmentioning

confidence: 99%

GPS-derived orbits for the GOCE satellite

Bock

Jäggi

Meyer

et al. 2011

J Geod

Self Cite

117

The first ESA (European Space Agency) Earth explorer core mission GOCE (Gravity field and steady-state Ocean Circulation Explorer) was launched on 17 March 2009 into a sun-synchronous dusk-dawn orbit with an exceptionally low initial altitude of about 280 km. The onboard 12-channel dual-frequency GPS (Global Positioning System) receiver delivers 1 Hz data, which provides the basis for precise orbit determination (POD) for such a very low orbiting satellite. As part of the European GOCE Gravity Consortium the Astronomical Institute of the University of Bern and the Department of Earth Observation and Space Systems are responsible for the orbit determination of the GOCE satellite within the GOCE High-level Processing Facility. Both quicklook (rapid) and very precise orbit solutions are produced with typical latencies of 1 day and 2 weeks, respectively. This article summarizes the special characteristics of the GOCE GPS data, presents POD results for about 2 months of data, and shows that both latency and accuracy requirements are met. Satellite Laser Ranging validation shows that an accuracy of 4 and 7 cm is achieved for the reduced-dynamic and kinematic Rapid Science Orbit solutions, respectively. The validation of the reduced-dynamic and kinematic Precise Science Orbit solutions is at a level of about 2 cm.

“…The GOCE satellite was equipped, among others, with two 12-channel dual-frequency Lagrange GPS hl-SST instruments (Intelisano et al 2008), each consisting of a geodetic-quality GPS receiver and a helix antenna. In this study, GPS data collected in the nominal phase of the GOCE mission spanning the time interval from November 2009 to July 2012 are used and the days with data problems are excluded as proposed in (Visser et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Earth’s gravity field modelling based on satellite accelerations derived from onboard GPS phase measurements

Ditmar

Zhao

et al. 2017

J Geod

GPS data collected by satellite gravity missions can be used for extracting the long-wavelength part of the Earth's gravity field. We propose a new data processing method which makes use of the 'average acceleration' approach to gravity field modelling. In this method, satellite accelerations are directly derived from GPS carrier phase measurements with an epoch-differenced scheme. As a result, no ambiguity solutions are needed and the systematic errors that do not change much from epoch to epoch are largely eliminated. The GPS data collected by the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) satellite mission are used to demonstrate the added value of the proposed method. An analysis of the residual accelerations shows that accelerations derived in this way are more precise, with noise being reduced by about 20 and 5% at the cross-track component and the other two components, respectively, as compared to those based on kinematic orbits. The accelerations obtained in this way allow the recovery of the gravity field to a slightly higher maximum degree compared to the solution based on kinematic orbits. Furthermore, the gravity field solution has an overall better performance. Errors in spherical harmonic coefficients are smaller, especially at low degrees. The cumulative geoid height error is reduced by about 15 and 5% up to degree 50 and 150, respectively. An analysis in the spatial domain shows that large errors along the geomagnetic equator, which are caused by a high electron density coupled with large short-term variations, are substantially reduced. Finally, the new method allows for a better observation of mass transport signals. In particular, sufficiently realistic signatures of regional mass anomalies in North America and south-west Africa are obtained.