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1.
Christian Siemes 《Journal of Geodesy》2018,92(1):33-45
The GOCE gravity gradiometer measured highly accurate gravity gradients along the orbit during GOCE’s mission lifetime from March 17, 2009, to November 11, 2013. These measurements contain unique information on the gravity field at a spatial resolution of 80 km half wavelength, which is not provided to the same accuracy level by any other satellite mission now and in the foreseeable future. Unfortunately, the gravity gradient in cross-track direction is heavily perturbed in the regions around the geomagnetic poles. We show in this paper that the perturbing effect can be modeled accurately as a quadratic function of the non-gravitational acceleration of the satellite in cross-track direction. Most importantly, we can remove the perturbation from the cross-track gravity gradient to a great extent, which significantly improves the accuracy of the latter and offers opportunities for better scientific exploitation of the GOCE gravity gradient data set. 相似文献
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Within the scope of the Global Geodetic Observing System, Doppler Orbit Determination and Radiopositioning Integrated by Satellite – as a geodetic technique – can provide precise and continuous monitoring of the geocenter motion related to mass redistribution in the Earth, ocean and atmosphere system. We have reanalyzed 1998 DORIS/SPOT-4 (Satellite pour l’ Observation de la Terre) data that were previously generating inconsistent geocenter positions (?65 cm offset). We show here that this error is due to an incorrect phase center correction provided with the DORIS preprocessed data resulting from a +12 cm offset in the cross-track direction that has been confirmed since. We also conclude that a 1 mm error in the cross-track offset of non-yawing sun-synchronous SPOT satellites will generate a ?6.5 mm error in the derived Z-geocenter. Other non-yawing satellites would also be affected by a similar effect whose amplitude could be easily estimated from the orbit inclination 相似文献
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联合星载GPS双频观测值与简化的动力学模型,在卫星运动方程中引入适当的伪随机脉冲参数,对SWARM卫星进行精密定轨。采用星载GPS相位观测值残差、重叠轨道以及与外部轨道对比等3种方法对SWARM卫星简化动力学定轨结果进行检核。结果表明:SWARM星载GPS相位观测值残差RMS为7~10mm;径向、切向以及法向6h重叠轨道差值RMS均在1cm左右,3个方向均无明显的系统误差。通过与欧空局(ESA)发布的精密轨道进行对比分析,径向轨道差值RMS为2~5cm,切向轨道差值RMS为2~5cm,法向轨道差值RMS为2~4cm,3D轨道差值RMS为4~7cm;SWARM-B定轨精度优于SWARM-A与SWARM-C。因此,采用简化动力学法与本文提供的定轨策略进行SWARM卫星精密定轨是切实可行的,定轨结果良好且稳定,定轨精度达到厘米级。 相似文献
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采用2015年5月24日—30日的Swarm星载GPS双频观测数据,基于Melbourne-Wübbena(MW)和消电离层线性组合,在精密单点定位技术的基础上,采用批处理最小二乘估计法对不同轨道高度的Swarm系列卫星进行非差运动学精密定轨。利用星载GPS相位观测值残差、与欧空局发布的简化动力学轨道对比,以及SLR检核3种方法对Swarm系列卫星非差运动学定轨结果进行精度评估。结果表明:①Swarm系列卫星星载GPS相位观测值残差RMS为6~7 mm;②与欧空局发布的简化动力学轨道进行求差,径向、切向及法向轨道差值RMS为2~4 cm;③与欧空局发布的运动学轨道进行求差,径向、切向及法向轨道差值RMS为1~2 cm;④SLR检核结果表明Swarm-A/B/C卫星轨道精度为3~4 cm。因此,采用非差运动学定轨方法与本文提供的定轨策略进行Swarm系列卫星精密定轨是切实可行的,定轨精度为厘米级。 相似文献
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Exploring gravity field determination from orbit perturbations of the European Gravity Mission GOCE 总被引：5，自引：0，他引：5
A comparison was made between two methods for gravity field recovery from orbit perturbations that can be derived from global
positioning system satellite-to-satellite tracking observations of the future European gravity field mission GOCE (Gravity
Field and Steady-State Ocean Circulation Explorer). The first method is based on the analytical linear orbit perturbation
theory that leads under certain conditions to a block-diagonal normal matrix for the gravity unknowns, significantly reducing
the required computation time. The second method makes use of numerical integration to derive the observation equations, leading
to a full set of normal equations requiring powerful computer facilities. Simulations were carried out for gravity field recovery
experiments up to spherical harmonic degree and order 80 from 10 days of observation. It was found that the first method leads
to large approximation errors as soon as the maximum degree surpasses the first resonance orders and great care has to be
taken with modeling resonance orbit perturbations, thereby loosing the block-diagonal structure. The second method proved
to be successful, provided a proper division of the data period into orbital arcs that are not too long.
Received: 28 April 2000 / Accepted: 6 November 2000 相似文献
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Orbit determination of the SELENE satellites using multi-satellite data types and evaluation of SELENE gravity field models 总被引：1，自引：0，他引：1
S. Goossens K. Matsumoto D. D. Rowlands F. G. Lemoine H. Noda H. Araki 《Journal of Geodesy》2011,85(8):487-504
The SELENE mission, consisting of three separate satellites that use different terrestrial-based tracking systems, presents
a unique opportunity to evaluate the contribution of these tracking systems to orbit determination precision. The tracking
data consist of four-way Doppler between the main orbiter and one of the two sub-satellites while the former is over the far
side, and of same-beam differential VLBI tracking between the two sub-satellites. Laser altimeter data are also used for orbit
determination. The contribution to orbit precision of these different data types is investigated through orbit overlap analysis.
It is shown that using four-way and VLBI data improves orbit consistency for all satellites involved by reducing peak values
in orbit overlap differences that exist when only standard two-way Doppler and range data are used. Including laser altimeter
data improves the orbit precision of the SELENE main satellite further, resulting in very smooth total orbit errors at an
average level of 18 m. The multi-satellite data have also resulted in improved lunar gravity field models, which are assessed
through orbit overlap analysis using Lunar Prospector tracking data. Improvements over a pre-SELENE model are shown to be
mostly in the along-track and cross-track directions. Orbit overlap differences are at a level between 13 and 21 m with the
SELENE models, depending on whether 1-day data overlaps or 1-day predictions are used. 相似文献
9.
TOPEX/Poseidon orbit error assessment 总被引：1，自引：0，他引：1
A. J. E. Smith E. T. Hesper D. C. Kuijper G. J. Mets P. N. A. M. Visser B. A. C. Ambrosius K. F. Wakker 《Journal of Geodesy》1996,70(9):546-553
This paper discusses the accuracy of TOPEX/Poseidon orbits computed at Delft University, Section Space Research & Technology (DUT/SSR&T), from several types of tracking data,i.e. SLR, DORIS, and GPS. To quantify the orbit error, three schemes are presented. The first scheme relies on the direct altimeter observations and the covariance of the JGM-2 gravity field. The second scheme is based on crossover difference residuals while the third scheme uses the differences of dynamic orbit solutions with the GPS reduced-dynamic orbit. All three schemes give comparable results and indicate that the radial orbit error of TOPEX/Poseidon is 3–4 cm. From the orbit comparisons with GPS reduced dynamic, both the along-track and cross-track errors of the dynamic orbit solutions were found to be within 10–15 cm. 相似文献
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基于低轨（low earth orbit,LEO）卫星星载GNSS反射事件的数学判据,分别用BDS、GPS、Galileo、GLONASS和4系统耦合GNSS星座模拟信号源,仿真分析了LEO卫星轨道高度、轨道倾角、下视天线视场角等参量对反射事件数量和时空分布的影响;进而研究了用上述4大GNSS系统进行GNSS反射信号遥感技术（GNSS reflectometry,GNSS-R）探测对接收机通道数量的需求。统计结果表明:LEO卫星轨道越高,天线视场越大,反射事件越多,镜面反射点分布越稠密;轨道倾角越小,反射事件镜面点越趋于赤道地区分布;GNSS-R接收机所需通道数随LEO卫星轨道高度和下视天线视场范围增大而增加;而LEO卫星轨道倾角变化对通道数需求影响不明显。研究结果对GNSS-R低轨卫星系统设计具有一定的理论参考价值。 相似文献
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在卫星动力学定轨中,太阳辐射压是一个重要的摄动因素,特别是对中高轨卫星的轨道。为了消弱太阳辐射压的影响,已经建立有诸多太阳辐射压模型,对应方法主要包括解析和经验两类,但各有优缺点和适用范围。基于现有方法的优点和卫星实际运行环境,对复杂结构卫星建立了一种结合预先解析法采样和运行后自适应改正的联合方法以趋近卫星真实辐射压环境的太阳辐射压模型;并对该模型进行了模拟计算。结果表明,该模型在轨道计算和自校正过程均取得了良好的效果。 相似文献
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太阳光压摄动作为在轨导航卫星受到的最大的非保守力,是卫星精密定轨的重要误差源。ECOM模型、ECOM2模型,这两种经验型光压模型被广泛应用于导航卫星定轨。然而,ECOM模型和ECOM2模型分别是针对GPS和GLONASS卫星设计的,并不完全适用于我国北斗三号(BDS-3)卫星。针对五参数ECOM模型在BDS-3卫星低太阳高度角时期轨道不连续性增大的问题,本文提出在 D方向引入一阶周期项来吸收未被模型化光压加速度。结果表明,引入一阶余弦周期项 Dc,能将低太阳高度角时期CAST卫星的切向、法向、径向重叠轨道误差分别减小约60%、52%、29%。针对ECOM2模型中 D2c和 D0、D2s和 Bs之间存在的强相关性,本文提出了不估计 D2c参数的八参数ECOM2模型和不估计 D2c与 D2s的七参数ECOM2模型。结果表明,相较九参数ECOM2模型,不估计 D2c参数的八参数ECOM2模型能够将CAST卫星和SECM卫星径向重叠轨道误差分别减少约18%和27%。在此基础上,继续移除 D2s后(七参数ECOM2),径向重叠轨道误差可进一步减小5.2%~8.5%。综合考察重叠轨道精度和SLR检核精度,不顾及 D2c和 D2s的七参数ECOM2模型表现最佳。CAST卫星和SECM卫星重叠轨道切向、法向、径向精度分别为5.0、3.4、1.4 cm和5.4、3.5、1.5 cm;SLR检核残差标准差分别为3.1~3.2 cm、4.4~4.7 cm。 相似文献
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首先描述卫星覆盖的理论以及卫星星下点在地面上的轨迹规律,然后根据导航星座的特点,通过对星座基本参数特点的讨论,并在参考GPS和GLONASS星座的基础上,确定了导航星座的构成。最后,在理论上证明了最小覆盖性的条件,随着模拟实际数据进行了验证。 相似文献
16.
广播星历参数拟合算法研究 总被引：7，自引：0，他引：7
导航卫星一般采用近圆轨道,当卫星轨道偏心率或者轨道倾角接近于0时,利用GPS卫星开普勒轨道根数拟合卫星广播星历会出现一些问题。当高轨卫星轨道偏心率接近0时,广播星历拟合精度下降甚至拟合失败,为此本文提出了减少拟合参数个数、固定轨道根数M0或者延长星历参数拟合弧段长度的方法;针对GEO卫星在小倾角情况下,广播星历可能拟合失败的情况,本文提出了改变坐标系参考轨道面,在新的坐标系下拟合广播星历的方法。结果表明,改进后的拟合方法能适用于各种类型的导航卫星轨道,拟合精度在cm级或者mm级。 相似文献
17.
Various formulations of the geodetic fixed and free boundary value problem are presented, depending upon the type of boundary data. For the free problem, boundary data of type astronomical latitude, astronomical longitude and a pair of the triplet potential, zero and first-order vertical gradient of gravity are presupposed. For the fixed problem, either the potential or gravity or the vertical gradient of gravity is assumed to be given on the boundary. The potential and its derivatives on the boundary surface are linearized with respect to a reference potential and a reference surface by Taylor expansion. The Eulerian and Lagrangean concepts of a perturbation theory of the nonlinear geodetic boundary value problem are reviewed. Finally the boundary value problems are solved by Hilbert space techniques leading to new generalized Stokes and Hotine functions. Reduced Stokes and Hotine functions are recommended for numerical reasons. For the case of a boundary surface representing the topography a base representation of the solution is achieved by solving an infinite dimensional system of equations. This system of equations is obtained by means of the product-sum-formula for scalar surface spherical harmonics with Wigner 3j-coefficients. 相似文献
18.
Various formulations of the geodetic fixed and free boundary value problem are presented, depending upon the type of boundary
data. For the free problem, boundary data of type astronomical latitude, astronomical longitude and a pair of the triplet
potential, zero and first-order vertical gradient of gravity are presupposed. For the fixed problem, either the potential
or gravity or the vertical gradient of gravity is assumed to be given on the boundary.
The potential and its derivatives on the boundary surface are linearized with respect to a reference potential and a reference
surface by Taylor expansion. The Eulerian and Lagrangean concepts of a perturbation theory of the nonlinear geodetic boundary
value problem are reviewed. Finally the boundary value problems are solved by Hilbert space techniques leading to new generalized
Stokes and Hotine functions. Reduced Stokes and Hotine functions are recommended for numerical reasons. For the case of a
boundary surface representing the topography a base representation of the solution is achieved by solving an infinite dimensional
system of equations. This system of equations is obtained by means of the product-sum-formula for scalar surface spherical
harmonics with Wigner 3j-coefficients. 相似文献
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Yanming Feng 《GPS Solutions》2001,5(2):1-11
Single-epoch point positioning with the global positioning system (GPS) is as accurate in low orbit as it is on the ground:
typically a three-dimensional rms accuracy of 20 to 30 m as the selective availability turns to zero. This is achieved at
any observation epoch without orbit dynamic information. With sophisticated models and filtering techniques onboard the spacecraft,
the orbit accuracy of a Low Earth Orbiter (LEO) can be improved to a few meters using the civilian broadcast GPS signals.
To achieve this accuracy autonomously in real time, an efficient onboard computing processor is required to carry out the
sophisticated orbit integration and filtering process.
In this paper, a new orbit integrator is presented that computes the nominal orbit states (the position and velocity) and
the state transition equations with numerical methods of integral equation, instead of differential equation usually used
for orbit computation. The algorithm is simple, and can be easily embedded in an onboard processor. The numerical results
demonstrate that the proposed method of the integral equation provides precise orbit predictions over several orbits. The
sequential filter based on the above integrator allows the use of simple orbit state equations to efficiently correct dynamical
model errors with precise GPS measurements or improve the orbits using GPS navigaion solutions from the 3D rms accuracy of
26 m to 3.7 m within a few hours of tracking. ? 2001 John Wiley & Sons, Inc. 相似文献