共查询到10条相似文献，搜索用时 93 毫秒
1.
Tzu-Pang Tseng Kefei Zhang Cheinway Hwang Urs Hugentobler Chuan-Sheng Wang Suelynn Choy Yi-Shan Li 《GPS Solutions》2014,18(2):219-230
We provide suggestions for the approved COSMIC-2 satellite mission regarding the field of view (FOV) and the clock stability of its future GNSS receiver based on numerical analyses using COSMIC GPS data. While the GRACE GPS receiver is mounted on the zenith direction, the precise orbit determination (POD) antennas of COSMIC are not. The COSMIC antenna design results in a narrow FOV and a reduction in the number of GPS observations. To strengthen the GPS geometry, GPS data from two POD antennas of COSMIC are used to estimate its orbits. The phase residuals of COSMIC are at the centimeter level, compared to the millimeter level of GRACE. The receiver clock corrections of COSMIC and GRACE are at the microsecond and nanosecond levels, respectively. The clock spectra of COSMIC at the frequencies of 0–0.005 Hz contain significant powers, indicating potential systematic errors in its clock corrections. The clock stability, expressed by the Allan deviation, of COSMIC ranges from 10?9 to 10?11 over 1 to 104 s, compared to 10?12 to 10?14 for GRACE. Compared to USO-based clock of GRACE, the clock of COSMIC is degraded in its stability and is linked to the reduction of GPS data quality. Lessons for improvement of COSMIC-2 over COSMIC in FOV and receiver clock stability are given. 相似文献
2.
Oliver Montenbruck Miquel Garcia-Fernandez Yoke Yoon Steffen Schön Adrian Jäggi 《GPS Solutions》2009,13(1):23-34
Phase center variations of the receiver and transmitter antenna constitute a remaining uncertainty in the high precision orbit
determination (POD) of low Earth orbit (LEO) satellites using GPS measurements. Triggered by the adoption of absolute phase
patterns in the IGS processing standards, a calibration of the Sensor Systems S67-1575-14 antenna with GFZ choke ring has
been conducted that serves as POD antenna on various geodetic satellites such as CHAMP, GRACE and TerraSAR-X. Nominal phase
patterns have been obtained with a robotic measurement system in a field campaign and the results were used to assess the
impact of receiver antenna phase patterns on the achievable positioning accuracy. Along with this, phase center distortions
in the actual spacecraft environment were characterized based on POD carrier phase residuals for the GRACE and TerraSAR-X
missions. It is shown that the combined ground and in-flight calibration can improve the carrier phase modeling accuracy to
a level of 4 mm which is close to the pure receiver noise. A 3.5 cm (3D rms) consistency of kinematic and reduced dynamic
orbit determination solutions is achieved for TerraSAR-X, which presumably reflects the limitations of presently available
GPS ephemeris products. The reduced dynamic solutions themselves match the observations of high grade satellite laser ranging
stations to 1.5 cm but are potentially affected by cross-track biases at the cm-level. With respect to the GPS based relative
navigation of TerraSAR-X/TanDEM-X formation, the in-flight calibration of the antenna phase patterns is considered essential
for an accurate modeling of differential carrier phase measurements and a mm level baseline reconstruction.
相似文献
| Oliver MontenbruckEmail: |
3.
Improved antenna phase center models for GLONASS 总被引：6，自引：2，他引：4
Rolf Dach Ralf Schmid Martin Schmitz Daniela Thaller Stefan Schaer Simon Lutz Peter Steigenberger Gerhard Wübbena Gerhard Beutler 《GPS Solutions》2011,15(1):49-65
Thanks to the increasing number of active GLONASS satellites and the increasing number of multi-GNSS tracking stations in
the network of the International GNSS Service (IGS), the quality of the GLONASS orbits has become significantly better over
the last few years. By the end of 2008, the orbit RMS error had reached a level of 3–4 cm. Nevertheless, the strategy to process
GLONASS observations still has deficiencies: one simplification, as applied within the IGS today, is the use of phase center
models for receiver antennas for the GLONASS observations, which were derived from GPS measurements only, by ignoring the
different frequency range. Geo++ GmbH calibrates GNSS receiver antennas using a robot in the field. This procedure yields
now separate corrections for the receiver antenna phase centers for each navigation satellite system, provided its constellation
is sufficiently populated. With a limited set of GLONASS calibrations, it is possible to assess the impact of GNSS-specific
receiver antenna corrections that are ignored within the IGS so far. The antenna phase center model for the GLONASS satellites
was derived in early 2006, when the multi-GNSS tracking network of the IGS was much sparser than it is today. Furthermore,
many satellites of the constellation at that time have in the meantime been replaced by the latest generation of GLONASS-M
satellites. For that reason, this paper also provides an update and extension of the presently used correction tables for
the GLONASS satellite antenna phase centers for the current constellation of GLONASS satellites. The updated GLONASS antenna
phase center model helps to improve the orbit quality. 相似文献
4.
5.
Generation of a consistent absolute phase-center correction model for GPS receiver and satellite antennas 总被引：26，自引：16，他引：10
Ralf Schmid Peter Steigenberger Gerd Gendt Maorong Ge Markus Rothacher 《Journal of Geodesy》2007,81(12):781-798
The development and numerical values of the new absolute phase-center correction model for GPS receiver and satellite antennas, as adopted by the International GNSS (global navigation satellite systems) Service, are presented. Fixing absolute receiver antenna phase-center corrections to robot-based calibrations, the GeoForschungsZentrum Potsdam (GFZ) and the Technische Universität München reprocessed more than 10 years of GPS data in order to generate a consistent set of nadir-dependent phase-center variations (PCVs) and offsets in the z-direction pointing toward the Earth for all GPS satellites in orbit during that period. The agreement between the two solutions estimated by independent software packages is better than 1 mm for the PCVs and about 4 cm for the z-offsets. In addition, the long time-series facilitates the study of correlations of the satellite antenna corrections with several other parameters such as the global terrestrial scale or the orientation of the orbital planes with respect to the Sun. Finally, completely reprocessed GPS solutions using different phase-center correction models demonstrate the benefits from switching from relative to absolute antenna phase-center corrections. For example, tropospheric zenith delay biases between GPS and very long baseline interferometry (VLBI), as well as the drift of the terrestrial scale, are reduced and the GPS orbit consistency is improved. 相似文献
6.
Precise orbit determination of the Sentinel-3A altimetry satellite using ambiguity-fixed GPS carrier phase observations 总被引：1，自引：0，他引：1
The Sentinel-3 mission takes routine measurements of sea surface heights and depends crucially on accurate and precise knowledge of the spacecraft. Orbit determination with a targeted uncertainty of less than 2 cm in radial direction is supported through an onboard Global Positioning System (GPS) receiver, a Doppler Orbitography and Radiopositioning Integrated by Satellite instrument, and a complementary laser retroreflector for satellite laser ranging. Within this study, the potential of ambiguity fixing for GPS-only precise orbit determination (POD) of the Sentinel-3 spacecraft is assessed. A refined strategy for carrier phase generation out of low-level measurements is employed to cope with half-cycle ambiguities in the tracking of the Sentinel-3 GPS receiver that have so far inhibited ambiguity-fixed POD solutions. Rather than explicitly fixing double-difference phase ambiguities with respect to a network of terrestrial reference stations, a single-receiver ambiguity resolution concept is employed that builds on dedicated GPS orbit, clock, and wide-lane bias products provided by the CNES/CLS (Centre National d’Études Spatiales/Collecte Localisation Satellites) analysis center of the International GNSS Service. Compared to float ambiguity solutions, a notably improved precision can be inferred from laser ranging residuals. These decrease from roughly 9 mm down to 5 mm standard deviation for high-grade stations on average over low and high elevations. Furthermore, the ambiguity-fixed orbits offer a substantially improved cross-track accuracy and help to identify lateral offsets in the GPS antenna or center-of-mass (CoM) location. With respect to altimetry, the improved orbit precision also benefits the global consistency of sea surface measurements. However, modeling of the absolute height continues to rely on proper dynamical models for the spacecraft motion as well as ground calibrations for the relative position of the altimeter reference point and the CoM. 相似文献
7.
高精度、高可靠性的卫星轨道是实现低轨卫星精密应用的重要前提,而模糊度固定技术是提高卫星定轨精度的关键途径。研究了基于整数钟的星间单差模糊度固定原理和方法,并利用2019年4月—5月的两颗GRACE-FO（gravity recovery and climate experiment follow on）卫星数据（GRACE-C/D）系统评估了固定解对低轨卫星简化动力学和运动学定轨的精度提升效果。结果表明,两颗卫星简化动力学和运动学定轨的宽巷模糊度固定率均达到99%,而窄巷模糊度固定率在95%左右。对于简化动力学定轨,GRACE-C/D固定解轨道的重叠轨道的3D均方根误差（root mean square error, RMSE）分别从7.1 mm和7.4 mm减小到了4.2 mm和3.6 mm;卫星激光测距（satellite laser ranging, SLR）残差标准差（standard deviation, STD）分别从15.9 mm和14.4 mm降低到了10.8 mm和11.0 mm,精度提升了32%和24%;K波段测距残差RMSE从8.0 mm减小到2.9 mm,进一步表明固定解还能有效提升低轨卫星间相对位置精度。对于运动学定轨,与精密科学轨道产品互差3D RMSE,浮点解分别为37.5 mm和36.4 mm,固定解分别为27.7 mm和25.5 mm,精度提升约28%,SLR残差STD也减小了约20%。 相似文献
8.
Zhigui Kang Byron Tapley Srinivas Bettadpur John Ries Peter Nagel Rick Pastor 《Journal of Geodesy》2006,80(6):322-331
The GRACE (gravity recovery and climate experiment) satellites, launched in March 2002, are each equipped with a BlackJack GPS onboard receiver for precise orbit determination and gravity field recovery. Since launch, there have been significant improvements in the background force models used for satellite orbit determination, most notably the model for the geopotential. This has resulted in significant improvements to orbit accuracy for very low altitude satellites. The purpose of this paper is to investigate how well the orbits of the GRACE satellites (about 470 km in altitude) can currently be determined using only GPS data and based on the current models and methods. The orbit accuracy is assessed using a number of tests, which include analysis of orbit fits, orbit overlaps, orbit connecting points, satellite Laser ranging residuals and K-band ranging (KBR) residuals. We show that 1-cm radial orbit accuracy for the GRACE satellites has probably been achieved. These precise GRACE orbits can be used for such purposes as improving gravity recovery from the GRACE KBR data and for atmospheric profiling, and they demonstrate the quality of the background force models being used. 相似文献
9.
GNSS卫星精密轨道是高精度GNSS应用的基础与前提,GNSS卫星精密定轨技术也一直都是卫星导航领域的研究重点与热点。本文首先介绍了GNSS星座与跟踪数据概况,梳理了精密定轨函数模型、动力学模型及随机模型构建过程中的关键问题,归纳了低轨星载观测和星间链路观测等多源数据增强GNSS精密定轨的研究进展;然后,从应用的角度总结了当前GNSS精密轨道产品的基本状态,并进行了精度评估;最后,讨论了GNSS精密定轨在大网快速解算、多层次观测数据融合、太阳光压模型精化及高精度实时定轨等方面所面临的挑战,并展望了低轨星座、光钟、激光链路等新技术给GNSS精密定轨带来的机遇。 相似文献
10.
由于天线本身的特性及机械加工等原因,GPS卫星和接收机天线相位中心与其几何中心不重合,从而产生相位中心偏差。某些类型的天线该偏差甚至可达数cm,直接影响高精度GPS测量的精确可靠性[1]。讨论了GAMIT软件在高精度GPS数据处理中进行天线相位中心改正的原理、方法和策略,结合美国IGS观测站及南加州区域站观测数据,对改正方法及策略进行了实验对比与分析。结果表明:对接收机天线相位中心和卫星天线相位中心采用模型改正,而卫星天线相位中心偏移不改正,所得到的基线解算结果较好[2];地面接收机天线方位角的变化对U方向的基线解算结果有较大影响,在高精度GPS测量中,必须进行天线方位角的变化改正。 相似文献