共查询到20条相似文献，搜索用时 31 毫秒
1.
Christopher Kotsakis 《Journal of Geodesy》2008,82(4-5):261-260
Transforming height information that refers to an ellipsoidal Earth reference model, such as the geometric heights determined
from GPS measurements or the geoid undulations obtained by a gravimetric geoid solution, from one geodetic reference frame
(GRF) to another is an important task whose proper implementation is crucial for many geodetic, surveying and mapping applications.
This paper presents the required methodology to deal with the above problem when we are given the Helmert transformation parameters
that link the underlying Cartesian coordinate systems to which an Earth reference ellipsoid is attached. The main emphasis
is on the effect of GRF spatial scale differences in coordinate transformations involving reference ellipsoids, for the particular
case of heights. Since every three-dimensional Cartesian coordinate system ‘gauges’ an attached ellipsoid according to its
own accessible scale, there will exist a supplementary contribution from the scale variation between the involved GRFs on
the relative size of their attached reference ellipsoids. Neglecting such a scale-induced indirect effect corrupts the values
for the curvilinear geodetic coordinates obtained from a similarity transformation model, and meter-level apparent offsets
can be introduced in the transformed heights. The paper explains the above issues in detail and presents the necessary mathematical
framework for their treatment.
An erratum to this article can be found at 相似文献
2.
We perform extensive simulations in order to assess the accuracy with which the position of a radio transmitter on the surface of the Moon can be determined by geodetic VLBI. We study how the quality and quantity of geodetic VLBI observations influence these position estimates and investigate how observations of such near-field objects affect classical geodetic parameters like VLBI station coordinates and Earth rotation parameters. Our studies are based on today’s global geodetic VLBI schedules as well as on those designed for the next-generation geodetic VLBI system. We use Monte Carlo simulations including realistic stochastic models of troposphere, station clocks, and observational noise. Our results indicate that it is possible to position a radio transmitter on the Moon using today’s geodetic VLBI with a two-dimensional horizontal accuracy of better than one meter. Moreover, we show that the next-generation geodetic VLBI has the potential to improve the two-dimensional accuracy to better than 5 cm. Thus, our results lay the base for novel observing concepts to improve both lunar research and geodetic VLBI. 相似文献
3.
By considering a deformable geodetic network, deforming in a linear-in-time mode, according to a coordinate-invariant model, it becomes possible to get an insight into the rank deficiency of the stacking procedure, which is the standard method for estimating initial station coordinates and constant velocities, from coordinate time series. Comparing any two out of the infinitely many least squares estimates of stacking unknowns (initial station coordinates, velocity components and transformation parameters for the reference system in each data epoch), it is proven that the two solutions differ only by a linear-in-time trend in the transformation parameters. These pass over to the initial coordinates (the constant term) and to the velocity estimates (the time coefficient part). While the difference in initial coordinates is equivalent to a change of the reference system at the initial epoch, the differences in velocity components do not comply with those predicted by the same change of reference system for all epochs. Consequently, the different velocity component estimates, obtained by introducing different sets of minimal constraints, correspond to physically different station velocities, which are therefore non-estimable quantities. The theoretical findings are numerically verified for a global, a regional and a local network, by obtaining solutions based on four different types of minimal constraints, three usual algebraic ones (inner or partial inner) and the lately introduced kinematic constraints. Finally, by resorting to the basic ideas of Felix Tisserand, it is explained why the station velocities are non-estimable quantities in a very natural way. The problem of the optimal choice of minimal constraints and, hence, of the corresponding spatio-temporal reference system is shortly discussed. 相似文献
4.
5.
J. Kodet K. U. Schreiber J. Eckl C. Plötz S. Mähler T. Schüler T. Klügel S. Riepl 《Journal of Geodesy》2018,92(9):1097-1112
The quality of the links between the different space geodetic techniques (VLBI, SLR, GNSS and DORIS) is still one of the major limiting factors for the realization of a unique global terrestrial reference frame that is accurate enough to allow the monitoring of the Earth system, i.e., of processes like sea level change, postglacial rebound and silent earthquakes. According to the specifications of the global geodetic observing system of the International Association of Geodesy, such a reference frame should be accurate to 1 mm over decades, with rates of change stable at the level of 0.1 mm/year. The deficiencies arise from inaccurate or incomplete local ties at many fundamental sites as well as from systematic instrumental biases in the individual space geodetic techniques. Frequently repeated surveys, the continuous monitoring of antenna heights and the geometrical mount stability (Lösler et al. in J Geod 90:467–486, 2016. https://doi.org/10.1007/s00190-016-0887-8) have not provided evidence for insufficient antenna stability. Therefore, we have investigated variations in the respective system delays caused by electronic circuits, which is not adequately captured by the calibration process, either because of subtle differences in the circuitry between geodetic measurement and calibration, high temporal variability or because of lacking resolving bandwidth. The measured system delay variations in the electric chain of both VLBI- and SLR systems reach the order of 100 ps, which is equivalent to 3 cm of path length. Most of this variability is usually removed by the calibrations but by far not all. This paper focuses on the development of new technologies and procedures for co-located geodetic instrumentation in order to identify and remove systematic measurement biases within and between the individual measurement techniques. A closed-loop optical time and frequency distribution system and a common inter-technique reference target provide the possibility to remove variable system delays. The main motivation for the newly established central reference target, locked to the station clock, is the combination of all space geodetic instruments at a single reference point at the observatory. On top of that it provides the unique capability to perform a closure measurement based on the observation of time. 相似文献
6.
The problem of “global height datum unification” is solved in the gravity potential space based on: (1) high-resolution local
gravity field modeling, (2) geocentric coordinates of the reference benchmark, and (3) a known value of the geoid’s potential.
The high-resolution local gravity field model is derived based on a solution of the fixed-free two-boundary-value problem
of the Earth’s gravity field using (a) potential difference values (from precise leveling), (b) modulus of the gravity vector
(from gravimetry), (c) astronomical longitude and latitude (from geodetic astronomy and/or combination of (GNSS) Global Navigation
Satellite System observations with total station measurements), (d) and satellite altimetry. Knowing the height of the reference
benchmark in the national height system and its geocentric GNSS coordinates, and using the derived high-resolution local gravity
field model, the gravity potential value of the zero point of the height system is computed. The difference between the derived
gravity potential value of the zero point of the height system and the geoid’s potential value is computed. This potential
difference gives the offset of the zero point of the height system from geoid in the “potential space”, which is transferred
into “geometry space” using the transformation formula derived in this paper. The method was applied to the computation of
the offset of the zero point of the Iranian height datum from the geoid’s potential value W
0=62636855.8 m2/s2. According to the geometry space computations, the height datum of Iran is 0.09 m below the geoid. 相似文献
7.
《Journal of Geodesy》1975,49(3):241-257
The parallelism of geodetic and satellite systems to the average terrestrial system is examined, under the assumption that
a geodetic system is a fixed framework invariant with respect to geodetic network adjustment. In this case a geodetic system
is rotated with respect to the average terrestrial system only about the ellipsoid normal of the initial point. The method
is demonstrated using coordinates and covariance matrices for BC-4 and SECOR satellite tracking stations computed by Mueller
and his co-workers. It is shown that the NAD geodetic system is scaled significantly larger than the satellite systems; the
SECOR satellite systems have significant Z-rotations with respect to the average terrestrial system; and the ETH geodetic
system may have a significant rotation with respect to the average terrestrial system. 相似文献
8.
In November 1968, a marine geodetic control point was established in the Pacific Ocean at a water depth of6,200 feet. The control point (reference point) consists of three underwater acoustic transponders, two of which are powered with
lead-acid batteries and the third with an underwater radioisotope power source “URIPS” with a10- to20- year life expectancy. Four independent measuring techniques (LORAC airborne line-crossing, satellite, ship inertial, and
acoustic techniques) were used to measure and determine the coordinates of the control point. Preliminary analysis of the
acoustic and airborne data indicates that high accuracies can be achieved in the establishment of geodetic reference points
at sea. Geodetic adjustment by the method of variation of coordinates yielded a standard point error of±50 to±66 feet in determining the unknown ship station. The original location of the ship station as determined by shipboard navigation
equipment was off by about1,600 feet.
Paper previously published in the Proceedings of the Second Marine Geodesy Symposium of the Marine Technology Society. 相似文献
9.
魏子卿 《武汉大学学报(信息科学版)》2011,(8):883-886,922
论述了有关大地坐标系的几个问题,它们大都与国家大地坐标系有关;为了坐标系的维持与应用,提出2000中国大地坐标系应由至少2 000个国家级GNSS连续运行站和若干GNSS复测站的坐标和速度实现;认为大地参考架的更新周期取决于参考架的实现精度与具体应用的要求。为满足1∶1 000比例尺测图的需要,大地参考架的更新周期大约为30 a。同时还对"动态大地基准"的说法进行了评说。 相似文献
10.
Younghee Kwak Mathis Bloßfeld Ralf Schmid Detlef Angermann Michael Gerstl Manuela Seitz 《Journal of Geodesy》2018,92(9):1047-1061
The Celestial Reference System (CRS) is currently realized only by Very Long Baseline Interferometry (VLBI) because it is the space geodetic technique that enables observations in that frame. In contrast, the Terrestrial Reference System (TRS) is realized by means of the combination of four space geodetic techniques: Global Navigation Satellite System (GNSS), VLBI, Satellite Laser Ranging (SLR), and Doppler Orbitography and Radiopositioning Integrated by Satellite. The Earth orientation parameters (EOP) are the link between the two types of systems, CRS and TRS. The EOP series of the International Earth Rotation and Reference Systems Service were combined of specifically selected series from various analysis centers. Other EOP series were generated by a simultaneous estimation together with the TRF while the CRF was fixed. Those computation approaches entail inherent inconsistencies between TRF, EOP, and CRF, also because the input data sets are different. A combined normal equation (NEQ) system, which consists of all the parameters, i.e., TRF, EOP, and CRF, would overcome such an inconsistency. In this paper, we simultaneously estimate TRF, EOP, and CRF from an inter-technique combined NEQ using the latest GNSS, VLBI, and SLR data (2005–2015). The results show that the selection of local ties is most critical to the TRF. The combination of pole coordinates is beneficial for the CRF, whereas the combination of \(\varDelta \hbox {UT1}\) results in clear rotations of the estimated CRF. However, the standard deviations of the EOP and the CRF improve by the inter-technique combination which indicates the benefits of a common estimation of all parameters. It became evident that the common determination of TRF, EOP, and CRF systematically influences future ICRF computations at the level of several \(\upmu \)as. Moreover, the CRF is influenced by up to \(50~\upmu \)as if the station coordinates and EOP are dominated by the satellite techniques. 相似文献
11.
Contribution of Starlette,Stella, and AJISAI to the SLR-derived global reference frame 总被引：3，自引：3，他引：0
Krzysztof Sośnica Adrian Jäggi Daniela Thaller Gerhard Beutler Rolf Dach 《Journal of Geodesy》2014,88(8):789-804
The contribution of Starlette, Stella, and AJISAI is currently neglected when defining the International Terrestrial Reference Frame, despite a long time series of precise SLR observations and a huge amount of available data. The inferior accuracy of the orbits of low orbiting geodetic satellites is the main reason for this neglect. The Analysis Centers of the International Laser Ranging Service (ILRS ACs) do, however, consider including low orbiting geodetic satellites for deriving the standard ILRS products based on LAGEOS and Etalon satellites, instead of the sparsely observed, and thus, virtually negligible Etalons. We process ten years of SLR observations to Starlette, Stella, AJISAI, and LAGEOS and we assess the impact of these Low Earth Orbiting (LEO) SLR satellites on the SLR-derived parameters. We study different orbit parameterizations, in particular different arc lengths and the impact of pseudo-stochastic pulses and dynamical orbit parameters on the quality of the solutions. We found that the repeatability of the East and North components of station coordinates, the quality of polar coordinates, and the scale estimates of the reference are improved when combining LAGEOS with low orbiting SLR satellites. In the multi-SLR solutions, the scale and the \(Z\) component of geocenter coordinates are less affected by deficiencies in solar radiation pressure modeling than in the LAGEOS-1/2 solutions, due to substantially reduced correlations between the \(Z\) geocenter coordinate and empirical orbit parameters. Eventually, we found that the standard values of Center-of-mass corrections (CoM) for geodetic LEO satellites are not valid for the currently operating SLR systems. The variations of station-dependent differential range biases reach 52 and 25 mm for AJISAI and Starlette/Stella, respectively, which is why estimating station-dependent range biases or using station-dependent CoM, instead of one value for all SLR stations, is strongly recommended. This clearly indicates that the ILRS effort to produce CoM corrections for each satellite, which are site-specific and depend on the system characteristics at the time of tracking, is very important and needs to be implemented in the SLR data analysis. 相似文献
12.
13.
L. Plank J. E. J. Lovell J. N. McCallum D. Mayer C. Reynolds J. Quick S. Weston O. Titov S. S. Shabala J. Böhm T. Natusch M. Nickola S. Gulyaev 《Journal of Geodesy》2017,91(7):803-817
The AUSTRAL observing program was started in 2011, performing geodetic and astrometric very long baseline interferometry (VLBI) sessions using the new Australian AuScope VLBI antennas at Hobart, Katherine, and Yarragadee, with contribution from the Warkworth (New Zealand) 12 m and Hartebeesthoek (South Africa) 15 m antennas to make a southern hemisphere array of telescopes with similar design and capability. Designed in the style of the next-generation VLBI system, these small and fast antennas allow for a new way of observing, comprising higher data rates and more observations than the standard observing sessions coordinated by the International VLBI Service for Geodesy and Astrometry (IVS). In this contribution, the continuous development of the AUSTRAL sessions is described, leading to an improvement of the results in terms of baseline length repeatabilities by a factor of two since the start of this program. The focus is on the scheduling strategy and increased number of observations, aspects of automated operation, and data logistics, as well as results of the 151 AUSTRAL sessions performed so far. The high number of the AUSTRAL sessions makes them an important contributor to VLBI end-products, such as the terrestrial and celestial reference frames and Earth orientation parameters. We compare AUSTRAL results with other IVS sessions and discuss their suitability for the determination of baselines, station coordinates, source coordinates, and Earth orientation parameters. 相似文献
14.
为了使G PS 的观测成果在实际中得到更好的应用,必须把 G PS 观测得到的WGS-84坐标转换成实际需要的国家大地坐标或地方独立坐标。本文利用 Excel软件的宏程序VBA进行编程,实现不同坐标系之间坐标的相互转换。并且例举了坐标转换的算例,实验表明：所编程序可以快捷、准确、可靠地解决不同坐标间的转换问题,能够满足实际工作的需要。 相似文献
15.
16.
Hugues Vermeille 《Journal of Geodesy》2011,85(2):105-117
A closed-form analytical method needing no approximation and deduced from a single quartic equation is offered to transform
geocentric into geodetic coordinates. It is valid at any point inside and outside the Earth including the polar axis, the
equatorial plane and the Earth’s center. Comparison with the method of extrema with constraints to obtain this quartic equation
is made. 相似文献
17.
我国大地坐标系的换代问题 总被引：22，自引：3，他引：22
魏子卿 《武汉大学学报(信息科学版)》2003,28(2):138-143,148
首先指出了我国现有大地坐标系在先进性和实用性方面存在的问题，提出了我们面临的选择与采用地心坐标系的建议，然后就地心坐标系的定义和实现、参考椭球常数、正常重力公式等问题提出了初步意见，并就坐标系改变对旧地形图的影响问题进行了研究。我国大地坐标系应由局部坐标系更新为地心坐标系。我国大地坐标系的定义应与IERS(国际地球自转服务)协议相一致，采用国际常用的参考椭球和正常重力公式。本文提出的参考椭球和正常重力公式符合这些原则，提出的地形图坐标系变化改正方案应是基本可行的。 相似文献
18.
GGOS-D: homogeneous reprocessing and rigorous combination of space geodetic observations 总被引：3，自引：3，他引：0
M. Rothacher D. Angermann T. Artz W. Bosch H. Drewes M. Gerstl R. Kelm D. K?nig R. K?nig B. Meisel H. M��ller A. Nothnagel N. Panafidina B. Richter S. Rudenko W. Schwegmann M. Seitz P. Steigenberger S. Tesmer V. Tesmer D. Thaller 《Journal of Geodesy》2011,85(10):679-705
In preparation of activities planned for the realization of the Global Geodetic Observing System (GGOS), a group of German scientists has carried out a study under the acronym GGOS-D which closely resembles the ideas behind the GGOS initiative. The objective of the GGOS-D project was the investigation of the methodological and information-technological realization of a global geodetic-geophysical observing system and especially the integration and combination of the space geodetic observations. In the course of this project, highly consistent time series of GPS, VLBI, and SLR results were generated based on common state-of-the-art standards for modeling and parameterization. These series were then combined to consistently and accurately compute a Terrestrial Reference Frame (TRF). This TRF was subsequently used as the basis to produce time series of station coordinates, Earth orientation, and troposphere parameters. In this publication, we present results of processing algorithms and strategies for the integration of the space-geodetic observations which had been developed in the project GGOS-D serving as a prototype or a small and limited version of the data handling and processing part of a global geodetic observing system. From a comparison of the GGOS-D terrestrial reference frame results and the ITRF2005, the accuracy of the datum parameters is about 5?C7?mm for the positions and 1.0?C1.5?mm/year for the rates. The residuals of the station positions are about 3?mm and between 0.5 and 1.0?mm/year for the station velocities. Applying the GGOS-D TRF, the offset of the polar motion time series from GPS and VLBI is reduced to 50 ??as (equivalent to 1.5?mm at the Earth??s surface). With respect to troposphere parameter time series, the offset of the estimates of total zenith delays from co-located VLBI and GPS observations for most stations in this study is smaller than 1.5?mm. The combined polar motion components show a significantly better WRMS agreement with the IERS 05C04 series (96.0/96.0???as) than VLBI (109.0/100.7???as) or GPS (98.0/99.5???as) alone. The time series of the estimated parameters have not yet been combined and exploited to the extent that would be possible. However, the results presented here demonstrate that the experiences made by the GGOS-D project are very valuable for similar developments on an international level as part of the GGOS development. 相似文献
19.
为贯彻《国家电网公司"十二五"信息发展规划》,落实国家电网信息化"SG186"工程的实施,实现"数字化电网、信息化企业"的目标,满足建设"统一智能电网"的需要,国家电网组织开发电网GIS空间信息服务平台。其中数据准备工作原则应遵循国家电网提出的整体性原则,以保证后续总部与网省纵向贯通的顺利进行,实现全国电网资源空间位置坐标的统一,对于空间参考系,国家要求新建立的地理信息系统均采用"CGCS2000国家大地坐标系"。但是,由于之前的测量系统均采用的是西安80坐标系或北京54坐标系,因此,如何将电力测量的坐标统一化是值得研究的问题。本文主要针对电力测量中西安80坐标与2000坐标的转换进行研究。 相似文献
20.
GPS测量坐标转换实用性问题的分析 总被引：12，自引：0，他引：12
针对ＧＰＳ测量坐标转换方法中存在的问题,提出了强制符合平面四参数法和多项式拟合法,这两种方法能够有效的克服高程系统以及椭球参数不一致造成的误差,比较适合于工程自由坐标之间的转换;同时本文给出了基于“全球大地水准面的几何中心地球质心相重合”这一假设之上的莫洛金斯坐标转换法,该法不需要联测公共点即可将ＷＧＳ－８４坐标转换成本地局部坐标。上述几种方法减少了额外联测的工作量,提高了ＧＰＳ的使用效率。 相似文献