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Joseph W. Siry 《Space Science Reviews》1973,14(2):314-341
The forthcoming 10 cm range tracking accuracy capability holds much promise in connection with a number of Earth and ocean
dynamics investigations. These include a set of earthquake-related studies of fault motions and the Earth's tidal, polar and
rotational motions, as well as studies of the gravity field and the sea surface topography which should furnish basic information
about mass and heat flow in the oceans.
The state of the orbit analysis art is presently at about the 10 m level, or about two orders of magnitude away from the 10
cm range accuracy capability expected in the next couple of years or so. The realization of a 10 cm orbit analysis capability
awaits the solution of four kinds of problems, namely, those involving orbit determination and the lack of sufficient knowledge
of tracking system biases, the gravity field, and tracking station locations.
The Geopause satellite system concept offers promising approaches in connection with all of these areas. A typical Geopause
satellite orbit has a 14 hour period, a mean height of about 4.6 Earth radii, and is nearly circular, polar, and normal to
the ecliptic. At this height only a relatively few gravity terms have uncertainties corresponding to orbital perturbations
above the decimeter level. The orbit s, in this sense, at the geopotential boundary, i.e., the geopause. The few remaining
environmental quantities which may be significant can be determined by means of orbit analyses and accelerometers. The Geopause
satellite system also provides the tracking geometery and coverage needed for determining the orbit, the tracking system biases
and the station locations. Studies indicate that the Geopause satellite, tracked with a 2 cm ranging system from nine NASA
affiliated sites, can yield decimeter station location accuracies. Five or more fundamental stations well distributed in longitude
can view Geopause over the North Pole. This means not only that redundant data are available for determining tracking system
biases, but also that both components of the polar motion can be observed frequently. When tracking Geopause, the NASA sites
become a two-hemisphere configuration which is ideal for a number of Earth physics applications such as the observation of
the polar motion with a time resolution of a fraction of a day.
Geopause also provides the basic capability for satellite-to-satellite tracking of drag-free satellites for mapping the gravity
field and altimeter satellites for surveying the sea surface topography. Geopause tracking a coplanar, drag-free satellite
for two months to 0.03 mm per second accuracy can yield the geoid over the entire Earth to decimeter accuracy with 2.5° spatial
resolution. Two Geopause satellites tracking a coplanar altimeter satellite can then yield ocean surface heights above the
geoid with 7° spatial resolution every two weeks. These data will furnish basic boundary condition information about mass
and heat flows in the oceans which are important in shaping weather and climate. 相似文献
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嫦娥四号月球探测拟首次实现月球背面的软着陆,测控与数传依赖地月L2平动点的中继卫星,并有望获取四程测量与星间测量数据。对基于中继测量的环月探测器测定轨能力进行了仿真分析,结果表明,中继卫星可较好地实现环月探测器连续跟踪;在定轨能力方面,中继卫星自身轨道精度是制约环月探测器定轨精度的重要因素,当跟踪弧段达到5h以上时,定轨精度趋于稳定,但轨道精度较中继卫星的轨道精度相差1个量级;对于星间链路测量,除中继卫星自身的轨道精度外,星钟的稳定性是制约定轨精度的另一个重要因素,如果辅助以每天1h的地基跟踪亦可实现优于百m的定轨精度。 相似文献
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The frequency band from 5.925 to 6.425 GHz is served by fixed satellites and by terrestrial microwave links. There is a possibility of microwave links pointed at the horizon causing interference to the uplinks of domestic and international communications satellites sharing the same frequency band. A mathematical model has been derived for predicting the fields at geostationary orbit based on the known characteristics and known distribution of the terrestrial microwave relay system. The Applications Technology Satellite-6 (ATS-6) is sensitive to signals in the range of 10 dBW radiated in the direction of the satellite. Signals in the range of 10-30 dBW have been recorded over various parts of the United States. 相似文献
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A method to improve satellite tracking accuracy is presented and discussed theoretically and experimentally in terms of two parts: correction for errors of the tracking system and correction of satellite orbit predictions. In the first part, it is concluded that the pointing error of the tracking system can be determined accurately using data from stellar observations, so that correction is possible with an accuracy of about 0.001°. In the second part, it is shown that apparent errors of satellite orbital elements can be deduced from the optical observation of one orbit, and one can track the satellite after the correction with high accuracy for several subsequent orbits. The accuracy is 0.1-0.2 mrad or better for satellites at 1000 km altitude when given orbit prediction accuracy is approximately 1°. 相似文献
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The telecommunications payload is described for the tracking and data relay satellite system (TDRSS). The salient design features of the electronic equipment, as well as the performance requirements that such equipment must satisfy to fulfill NASA and Western Union communication functions are presented. Operational characteristics associated with the single and multiple access channels used to relay information to and from users are also highlighted. 相似文献
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Boor J.L. Braunstein J. Janky J.M. Ogden D. Potter J.G. Harper E.L. Volkmer E. Whalen A.A. Henderson E. Hupe H.H. 《IEEE transactions on aerospace and electronic systems》1975,(6):1015-1032
The Health/Education Telecommunications (HET) Experiment involved six different experiments conducted under the auspices of the Department of Health, Education, and Welfare (HEW) with technical assistance from NASA. The HET Experiment on ATS-6 was operated and controlled from a network coordination center in Denver, Colo., which included a 4-and 6-GHz Earth station. The HET Experiment used remote Earth terminals with 3-m-diameter dishes having a 35 dB gain at 2.5 GHz. In addition, comprehensive terminals operating at both C-band and S-band were used for communications with Alaska. The total network involved a complex of satellite and land links at C-band, S-band, and very high frequency (VHF), using the ATS-1, ATS-3, and ATS-6 satellites. The network performance exceeded expectations with remote terminal operations exhibiting a peak-to-peak signal to weighted rms noise ratio of 49 dB at least 99 percent of the time. The remote site operators performed well and were well motivated although they had little previous technical experience. 相似文献
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Global Gravity Field Recovery Using Solely GPS Tracking and Accelerometer Data from Champ 总被引:2,自引:0,他引:2
Reigber C. Balmino G. Schwintzer P. Biancale R. Bode A. Lemoine J.-M. König R. Loyer S. Neumayer H. Marty J.-C. Barthelmes F. Perosanz F. Zhu S. Y. 《Space Science Reviews》2003,108(1-2):55-66
A new long-wavelength global gravity field model, called EIGEN-1, has been derived in a joint German-French effort from orbit
perturbations of the CHAMP satellite, exploiting CHAMP-GPS satellite-to-satellite tracking and on-board accelerometer data
over a three months time span. For the first time it becomes possible to recover the gravity field from one satellite only.
Thanks to CHAMP'S tailored orbit characteristics and dedicated instrumentation, providing continuous tracking and on-orbit
measurements of non-gravitational satellite accelerations, the three months CHAMP-only solution provides the geoid and gravity
with an accuracy of 20 cm and 1 mgal, respectively, at a half wavelength resolution of 550 km, which is already an improvement
by a factor of two compared to any pre-CHAMP satellite-only gravity field model.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Liqian ZHAO Xiaogong HU Chengpan TANG Shanshi ZHOU Yueling CAO Qianxin WANG Ranran SU 《中国航空学报》2022,35(4):332-343
Precise Point Positioning(PPP) requires precise products, including high-accuracy satellite orbit and clock parameters. It is impossible to obtain an orbit solution that is sufficiently accurate for PPP services with a regional tracking network; therefore, satellite orbits are usually estimated by a global tracking network with a large number of ground stations. However, it is expensive to build globally distributed stations. Fortunately, BeiDou-3 satellites carry an InterSatellite Link(ISL) pay... 相似文献
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建立了基于双星定位系统距离和观测数据的近地卫星联合定轨模型,设计了相应的数值融合联合定轨算法;为进一步提高近地卫星定轨精度,考虑融合双星及备份星距离和观测数据,建立了基于双星和备份星的近地卫星联合定轨模型及实现算法,并针对不同仿真条件进行了联合定轨仿真实验。仿真计算结果表明,联合定轨方式较传统近地卫星精密定轨方式可以更好地抑制双星星历误差对近地卫星定轨精度的影响,近地卫星和双星的定轨精度均得到了一定程度的提高;同时,融合备份星观测数据的近地卫星联合定轨精度得到进一步改善,达到5.17m。 相似文献
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The ATS-6 is the most advanced experimental satellite that has evolved from the Application Technology Satellite Program conducted and implemented by NASA Goddard Space Flight Center (NASA/GSFC). This project utilizes a state-of-the-art spacecraft and ground terminal network to perform advance studies and to conduct technological demonstrations in a large number of scientific areas. The design and implementation of this unique spacecraft permitted multiple experimentation simultaneously. The control of the spacecraft is performed at ATS Operational Control Center (ATSOCC) located at NASA/GSFC. Experimentation which was performed covered a wide spectrum of communications, technological, meterorological, and scientific subjects. Three principal ground terminals are utilized to assist the experimenters to acquire data. Data reduction and analysis are performed by the many facilities at NASA/GSFC in support of the experimenters. 相似文献
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Considerable experience accumulated during the past decade in strategies for processing GPS data from ground-based geodetic
receivers. First experience on the use of GPS observations from spaceborne receivers for orbit determination of satellites
on low altitude orbits was gained with the launch of TOPEX/POSEIDON ten years ago. The launch of the CHAMP satellite in July
2000 stimulated a number of activities worldwide on improving the strategies and algorithms for orbit determination for Low
Earth Orbiters (LEOs) using the GPS.
Similar strategies as for ground-based receivers are applied to data from spaceborne GPS receivers to determine high precision
orbits. Zero- and double-differencing techniques are applied to obtain kinematic and/or reduced-dynamic orbits with an accuracy
which is today at the decimeter level. Further developments in modeling and processing strategies will continuously improve
the quality of GPS-derived LEO orbits in the near future. A significant improvement can be expected from fixing double-difference
phase ambiguities to integer numbers. Particular studies focus on the impact of a combined processing of LEO and GPS orbits
on the quality of orbits and the reference frame realization.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Bertiger W.I. Lichten S.M. Katsigris E.C. 《Aerospace and Electronic Systems Magazine, IEEE》1989,4(2):16-25
High-accuracy orbits have been determined for satellites of the Global Positioning System (GPS), with submeter orbit accuracy demonstrated for two well-tracked satellites. Baselines of up to 2000 km in North America determined with the GPS orbits shows daily repeatability of 0.3-2 parts in 108 and agree with very long baseline interferometry (VLBI) solutions at the level of 1.5 parts in 10 8. Tests used to assess orbit accuracy include orbit repeatability from independent data sets, orbit prediction, ground baseline determination, and formal errors. One satellite tracked for eight hours each day shows RMS errors below 1 m even when predicted more than three days outside of a 1-week data arc. These results demonstrate the powerful relative positioning capability available from differential GPS tracking. Baselines have also been estimated between Florida and sites in the Caribbean region over 1000 km away, with daily repeatability of 1-4 parts in 108. The best orbit estimation strategies included data arcs of 1-2 weeks, process noise models for tropospheric fluctuations, combined processing of GPS carrier phase and pseudorange data, and estimation of GPS solar pressure coefficients 相似文献
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中继卫星在跟踪自主机动用户目标时,由于机动轨道未知,需要利用中继卫星下传的星载GNSS(Global Navigations Satellite System,全球导航卫星系统)数据进行实时轨道确定与预报,为中继卫星跟踪提供实时的引导信息,以方便中继卫星快速捕获目标和连续稳定跟踪。针对该类用户目标的任务需求,讨论了基于星载GNSS数据自主机动条件下的实时定轨方法,建立了连续推力机动力学模型。以某一型号卫星的实测数据进行分析验证,并对轨道机动进行辨识,计算的机动加速度和机动时间与试验单位提供的结果一致。针对卫星不同机动情况,5min的观测数据定轨预报10min的弧段,最大位置误差小于8km,可以为中继卫星快速捕获提供高精度的引导信息。 相似文献
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Shenk W.E. Stephanides C.C. Sonnek G.E. Howell L.D. 《IEEE transactions on aerospace and electronic systems》1975,(6):1095-1102
The Geosynchronous Very High Resolution Radiometer (GVHRR), flown on the three-axis stabilized geosynchronous satellite, Applications Technology Satellite-6 (ATS-6), collected meteorological data for two months during the summer of 1974. Several hundred images were successfully taken. Data collection terminated when the instrument chopper motor failed. The instrument, its supporting ground equipment, and the data collected in orbit are described. 相似文献
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Oli P.V.S. Nagarajan N. Rayan H.R. 《IEEE transactions on aerospace and electronic systems》1993,29(3):696-705
The concept of meridian orbits is briefly reviewed. It is shown that, if a satellite in the meridian orbit makes an odd number (>1) of revolutions per day, then the satellite passes over the same set of meridians twice a day. Satellites in such orbits pass over the same portion of the sky twice a day and every day. This enables a user to adopt a programmed mode of tracking, thereby avoiding a computational facility for orbit prediction, look angle generation, and auto tracking. A constellation of 38 or more satellites placed in a 1200-km altitude circular orbit is favorable for global communications due to various factors. It is shown that appropriate phasing in right ascension of the ascending node and mean anomaly results in a constellation wherein each satellite appears over the user's horizon one satellite after another. Visibility and coverage plots are provided to verify the continuous coverage 相似文献