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1.
The space segment of the European Global Navigation Satellite System (GNSS) Galileo consists of In-Orbit Validation (IOV) and Full Operational Capability (FOC) spacecraft. The first pair of FOC satellites was launched into an incorrect, highly eccentric orbital plane with a lower than nominal inclination angle. All Galileo satellites are equipped with satellite laser ranging (SLR) retroreflectors which allow, for example, for the assessment of the orbit quality or for the SLR–GNSS co-location in space. The number of SLR observations to Galileo satellites has been continuously increasing thanks to a series of intensive campaigns devoted to SLR tracking of GNSS satellites initiated by the International Laser Ranging Service. This paper assesses systematic effects and quality of Galileo orbits using SLR data with a main focus on Galileo satellites launched into incorrect orbits. We compare the SLR observations with respect to microwave-based Galileo orbits generated by the Center for Orbit Determination in Europe (CODE) in the framework of the International GNSS Service Multi-GNSS Experiment for the period 2014.0–2016.5. We analyze the SLR signature effect, which is characterized by the dependency of SLR residuals with respect to various incidence angles of laser beams for stations equipped with single-photon and multi-photon detectors. Surprisingly, the CODE orbit quality of satellites in the incorrect orbital planes is not worse than that of nominal FOC and IOV orbits. The RMS of SLR residuals is even lower by 5.0 and 1.5 mm for satellites in the incorrect orbital planes than for FOC and IOV satellites, respectively. The mean SLR offsets equal \(-44.9, -35.0\), and \(-22.4\) mm for IOV, FOC, and satellites in the incorrect orbital plane. Finally, we found that the empirical orbit models, which were originally designed for precise orbit determination of GNSS satellites in circular orbits, provide fully appropriate results also for highly eccentric orbits with variable linear and angular velocities.  相似文献   

2.
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   

3.
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   

4.
By the beginning of 1996 the Russian Global Navigation Satellite System (GLONASS) constellation was completely deployed, although several satellites have already been decommissioned since then. With 17 satellites in operation (status as of 21 December 1997, although two of them are unusable and one is a non-operative spare), GLONASS is now an alternative and a complement to GPS. We present an evaluation of the current status of the GLONASS system, paying particular attention to its possible geodetic applications. Data from several receivers were used for this evaluation, including data from GPS receivers in order to allow for a comparison between GLONASS and GPS. We tested the quality of the geodetic observables, the consistency of the broadcast orbits, the single-point positioning results, and we also looked at multipath errors and cycle slips in our GLONASS data. In general the GLONASS performance has been found to be very satisfactory, even better than GPS in aspects such as single-receiver positioning or in the quality of the second-frequency pseudo-ranges due to the degradation of the GPS measurement quality under selective availability and anti-spoofing. Received: 26 November 1996 / Accepted: 16 January 1998  相似文献   

5.
Precise ERS-2 orbit determination using SLR, PRARE, and RA observations   总被引：2，自引：0，他引：2  
The second European Remote Sensing satellite ERS-2, launched in 1995, is supported by satellite laser ranging (SLR), the German precise range and range-rate equipment (PRARE) microwave tracking system, and radar altimetry (RA). SLR, PRARE and crossover RA observations (XO/RA) from May, June, and July 1996 have been analyzed using the GEOSAT software developed at Forsvarets forskningsinstitutt (FFI, The Norwegian defence research establishment). Orbits computed with the JGM3 gravity model and the more recent EGM96 gravity model have been compared with orbits from other analysis centers. Based on these comparisons in addition to the post-fit observation residuals, and results from internal orbital overlaps, we conclude that the radial component of the ERS-2 orbit can be determined with a precision of 6 cm. Received: 30 June 1997 / Accepted: 4 February 1998  相似文献   

6.
利用Jason-3星载GPS观测数据,采用简化动力学方法和运动学方法对Jason-3卫星进行精密定轨研究. 通过载波相位残差、重叠轨道对比、参考轨道对比和卫星激光测距(SLR)轨道检核四种方式评定轨道精度. 计算相位残差均方根(RMS)值,简化动力学轨道的RMS值在0.7～0.8 cm,运动学轨道的RMS值在0.50～0.55 cm;简化动力学轨道重叠部分径向RMS值达到0.32 cm,运动学轨道重叠部分径向RMS值达到1.12 cm;与国际DORIS服务(IDS)官方提供的参考轨道对比,简化动力学轨道径向精度达到1.47 cm,运动学轨道径向精度达到4.36 cm;利用SLR观测数据进行核验,简化动力学轨道精度整体优于2.1 cm,运动学轨道精度整体优于3.3 cm. 通过实验证明:Jason-3卫星的简化动力学轨道和运动学轨道的精度均达到cm级.   相似文献   

7.
This study is concerned with gravity field recovery from low-low satellite to satellite range rate data. Compared against a coplanar mission an improvement is predicted in errors associated with certain parts of the geopotential by the separation of the orbital planes of the two satellites. Using Hill's equations an analytical scheme is developed to model the range rate residuals. It is flexible enough to model the residuals between pairs of satellites in the same orbital plane or whose planes are separated in right ascension. This scheme should allow the possibility of larger planar separations than previously since no small angle approximation is made. The effects of such an orientation on gravity field recovery can therefore be analysed by means of an extensive error analysis. The results of this analysis indicate that a significant improvement in the errors of the near sectorial coefficients are obtained when the satellite's orbital planes are separated. Received: 9 April 1996; Accepted: 26 September 1996  相似文献   

8.
SLR资料精密测定GLONASS卫星轨道   总被引：3，自引：0，他引：3  
将SLR资料计算的轨道与CODE轨道进行了比较，并将比较结果转换到RTN坐标系中。通过比较分析发现，两种轨道差值在轨道径向、法向和沿轨方向的精度分别优于10cm、50cm和45cm；SLR和微波资料确定的GLONASS卫星轨道在径向存在系统误差，该系统误差随卫星轨道面的不同而不同。  相似文献   

9.
重力恢复和气候实验(gravity recovery and climate experiment,GRACE)任务受限于卫星的低轨极地轨道性质和编队模式,确定的重力场模型C20项存在不足。与之相比,全球定位系统(global positioning system,GPS)卫星为倾斜轨道,卫星数量多,将GPS卫星的精密轨道数据作为伪观测值,使用动力学方法进行C20项确定的可行性研究。结果显示,2017年C20项时间序列的平均值比GRACE更接近卫星激光测距(satellite laser ranging,SLR)的结果,且不存在明显的约160 d的周期信号,表明利用GPS卫星解算C20项具有可行性。同时估计了光压模型P1参数,与GAMIT软件解算结果接近,进一步验证C20项解算结果的可靠性。  相似文献   

10.
星蚀期北斗卫星轨道性能分析——SLR检核结果   总被引：1，自引：0，他引：1  
星蚀期北斗卫星的轨道性能是北斗卫星导航系统性能分析的重要部分。了解北斗卫星导航系统星历中星蚀期轨道的精度,不仅可为系统服务性能评估提供支持,还有助于了解星蚀期精密定轨中相关模型可能存在的问题,进而为精密定轨函数模型改进提供参考。本文基于2014年1月至2015年7月的卫星激光测距资料,重点分析了星蚀期对北斗不同类型卫星轨道的影响,同时也对北斗广播星历和精密星历中整体轨道径向精度进行检核。结果表明:星蚀期内(尤其是偏航机动期间),IGSO/MEO卫星的广播星历和精密星历轨道均存在明显的精度下降;广播星历轨道径向误差达1.5~2.0m,精密星历轨道径向误差超过10.0cm。但仅从轨道径向残差序列中难以发现星蚀期对GEO卫星轨道是否有显著影响。非星蚀期间,IGSO/MEO卫星和GEO卫星的广播星历轨道径向精度分别优于0.5 m和0.9 m。IGSO/MEO卫星的精密星历轨道径向精度优于10.0cm,GEO卫星的轨道径向精度约50.0cm,且存在40.0cm左右的系统性偏差。  相似文献   

11.
Autonomous orbit determination is the ability of navigation satellites to estimate the orbit parameters on-board using inter-satellite link (ISL) measurements. This study mainly focuses on data processing of the ISL measurements as a new measurement type and its application on the centralized autonomous orbit determination of the new-generation Beidou navigation satellite system satellites for the first time. The ISL measurements are dual one-way measurements that follow a time division multiple access (TDMA) structure. The ranging error of the ISL measurements is less than 0.25 ns. This paper proposes a derivation approach to the satellite clock offsets and the geometric distances from TDMA dual one-way measurements without a loss of accuracy. The derived clock offsets are used for time synchronization, and the derived geometry distances are used for autonomous orbit determination. The clock offsets from the ISL measurements are consistent with the L-band two-way satellite, and time–frequency transfer clock measurements and the detrended residuals vary within 0.5 ns. The centralized autonomous orbit determination is conducted in a batch mode on a ground-capable server for the feasibility study. Constant hardware delays are present in the geometric distances and become the largest source of error in the autonomous orbit determination. Therefore, the hardware delays are estimated simultaneously with the satellite orbits. To avoid uncertainties in the constellation orientation, a ground anchor station that “observes” the satellites with on-board ISL payloads is introduced into the orbit determination. The root-mean-square values of orbit determination residuals are within 10.0 cm, and the standard deviation of the estimated ISL hardware delays is within 0.2 ns. The accuracy of the autonomous orbits is evaluated by analysis of overlap comparison and the satellite laser ranging (SLR) residuals and is compared with the accuracy of the L-band orbits. The results indicate that the radial overlap differences between the autonomous orbits are less than 15.0 cm for the inclined geosynchronous orbit (IGSO) satellites and less than 10.0 cm for the MEO satellites. The SLR residuals are approximately 15.0 cm for the IGSO satellites and approximately 10.0 cm for the MEO satellites, representing an improvement over the L-band orbits.  相似文献   

12.
香港实时GPS水汽监测系统的若干关键技术   总被引：8，自引：1，他引：7  
香港已经建成实时GPS水汽监测系统。主要介绍实时估计可降水分中的几个关键技术问题,如梯度模型、干分量模型的标定、湿分量至可降水分的区域性转换参数计算,以及预报卫星星历中粗差的探测方法等。最后,采用双差网解和非差精密单点定位两种数据处理方法,分别计算可降水份,并进行比较。  相似文献   

13.
吴甜甜  张云  刘永明  袁国良 《遥感学报》2014,18(5):1087-1097
随着北斗卫星导航系统的逐渐完善,有关北斗系统定位的研究越来越深入,为了对比分析北斗系统和全球定位导航系统(GPS)定位的差异性,充分利用北斗地球静止轨道卫星(GEO)和倾斜地球同步轨道卫星(IGSO)高轨道卫星的特殊性,本文提出一种新的组合选星方法,选取卫星数较少且Position Dilution of Precision(PDOP)最小的北斗/GPS组合,分别对比分析北斗系统、GPS系统及其组合系统在楼顶开放环境和楼间恶劣环境下的定位效果。实验结果表明:北斗比GPS有更加稳定的定位效果,依据本文组合选星方法,利用少量卫星即可获得较好的定位精度。  相似文献   

14.
The paper presents the results of crustal deformation, as evidenced by changed station coordinates, in the Tokyo metropolitan area detected by the satellite laser ranging (SLR) technique. The coordinates of two Key Stone SLR stations, Tateyama and Kashima, were determined from 4 weeks of orbital arcs of the LAGEOS-1 and LAGEOS-2 satellites with respect to 16 SLR stations kept fixed in the ITRF2000 reference frame. The station coordinates were calculated using the NASA GEODYN-II orbital program. The orbital RMS-of-fit for both satellites was 16 mm. The standard deviation of the estimated positions was 3 mm. A jump of about 5 cm in the baseline length between the Kashima and Tateyama stations was detected in June–August 2000 by VLBI and GPS techniques. This work confirms this crustal deformation as determined by SLR and vice versa. Analysis of coordinates of these stations shows that this effect was caused by a 4.5-cm displacement of the Tateyama station in the north-east direction. The change in the vertical component was not significant.  相似文献   

15.
Precise orbit determination for the GRACE mission using only GPS data   总被引：1，自引：1，他引：1  
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   

16.
关于GPS卫星的轨道分析   总被引：1，自引：0，他引：1  
刘林  周建华 《测绘学报》1992,21(3):173-182
  相似文献   

17.
On the precision and accuracy of IGS orbits   总被引：10，自引：6，他引：4  
In order to explore the precision and accuracy of International GNSS Service (IGS) orbits, we difference geocentric satellite positions midway between successive daily Final orbits for the period starting 5 November 2006, when the IGS switched its method of antenna calibration, through 31 December 2007. This yields a time series of orbit repeatabilities analogous to the classical geodetic test for position determinations. If we compare our average positional discontinuities to the official IGS accuracy codes, root-sum-squared (RSS) for each pair of days, we find the discontinuities are not well correlated with the predicted performance values. If instead the IGS weighted root-mean-square (WRMS) values from the Final combination long-arc analyses are taken as the measure of IGS accuracy, we find the position differences and long-arc values are correlated, but the long-arc values are exaggerated, particularly around eclipses, despite the fact that our day-boundary position differences apply to a single epoch each day and the long-arc analyses consider variations over a week. Our method is not well suited to probe the extent to which systematic effects dominate over random orbit errors, as indicated by satellite laser ranging residuals, but eclipsing satellites often display the most problematic behavior. A better metric than the current IGS orbit accuracy codes would probably be one based on the orbit discontinuities between successive days.  相似文献   

18.
Combination of GNSS and SLR observations using satellite co-locations   总被引：6，自引：6，他引：0  
Satellite Laser Ranging (SLR) observations to Global Navigation Satellite System (GNSS) satellites may be used for several purposes. On one hand, the range measurement may be used as an independent validation for satellite orbits derived solely from GNSS microwave observations. On the other hand, both observation types may be analyzed together to generate a combined orbit. The latter procedure implies that one common set of orbit parameters is estimated from GNSS and SLR data. We performed such a combined processing of GNSS and SLR using the data of the year 2008. During this period, two GPS and four GLONASS satellites could be used as satellite co-locations. We focus on the general procedure for this type of combined processing and the impact on the terrestrial reference frame (including scale and geocenter), the GNSS satellite antenna offsets (SAO) and the SLR range biases. We show that the combination using only satellite co-locations as connection between GNSS and SLR is possible and allows the estimation of SLR station coordinates at the level of 1–2 cm. The SLR observations to GNSS satellites provide the scale allowing the estimation of GNSS SAO without relying on the scale of any a priori terrestrial reference frame. We show that the necessity to estimate SLR range biases does not prohibit the estimation of GNSS SAO. A good distribution of SLR observations allows a common estimation of the two parameter types. The estimated corrections for the GNSS SAO are 119 mm and −13 mm on average for the GPS and GLONASS satellites, respectively. The resulting SLR range biases suggest that it might be sufficient to estimate one parameter per station representing a range bias common to all GNSS satellites. The estimated biases are in the range of a few centimeters up to 5 cm. Scale differences of 0.9 ppb are seen between GNSS and SLR.  相似文献   

19.
This article describes the processing strategy and the validation results of CODE’s MGEX (COM) orbit and satellite clock solution, including the satellite systems GPS, GLONASS, Galileo, BeiDou, and QZSS. The validation with orbit misclosures and SLR residuals shows that the orbits of the new systems Galileo, BeiDou, and QZSS are affected by modelling deficiencies with impact on the orbit scale (e.g., antenna calibration, Earth albedo, and transmitter antenna thrust). Another weakness is the attitude and solar radiation pressure (SRP) modelling of satellites moving in the orbit normal mode—which is not yet correctly considered in the COM solution. Due to these issues, we consider the current state COM solution as preliminary. We, however, use the long-time series of COM products for identifying the challenges and for the assessment of model-improvements. The latter is demonstrated on the example of the solar radiation pressure (SRP) model, which has been replaced by a more generalized model. The SLR validation shows that the new SRP model significantly improves the orbit determination of Galileo and QZSS satellites at times when the satellite’s attitude is maintained by yaw-steering. The impact of this orbit improvement is also visible in the estimated satellite clocks—demonstrating the potential use of the new generation satellite clocks for orbit validation. Finally, we point out further challenges and open issues affecting multi-GNSS data processing that deserves dedicated studies.  相似文献   

20.
Homogeneous reprocessing of GPS,GLONASS and SLR observations   总被引：3，自引：2，他引：1  
The International GNSS Service (IGS) provides operational products for the GPS and GLONASS constellation. Homogeneously processed time series of parameters from the IGS are only available for GPS. Reprocessed GLONASS series are provided only by individual Analysis Centers (i. e. CODE and ESA), making it difficult to fully include the GLONASS system into a rigorous GNSS analysis. In view of the increasing number of active GLONASS satellites and a steadily growing number of GPS+GLONASS-tracking stations available over the past few years, Technische Universität Dresden, Technische Universität München, Universität Bern and Eidgenössische Technische Hochschule Zürich performed a combined reprocessing of GPS and GLONASS observations. Also, SLR observations to GPS and GLONASS are included in this reprocessing effort. Here, we show only SLR results from a GNSS orbit validation. In total, 18 years of data (1994–2011) have been processed from altogether 340 GNSS and 70 SLR stations. The use of GLONASS observations in addition to GPS has no impact on the estimated linear terrestrial reference frame parameters. However, daily station positions show an RMS reduction of 0.3 mm on average for the height component when additional GLONASS observations can be used for the time series determination. Analyzing satellite orbit overlaps, the rigorous combination of GPS and GLONASS neither improves nor degrades the GPS orbit precision. For GLONASS, however, the quality of the microwave-derived GLONASS orbits improves due to the combination. These findings are confirmed using independent SLR observations for a GNSS orbit validation. In comparison to previous studies, mean SLR biases for satellites GPS-35 and GPS-36 could be reduced in magnitude from \(-35\) and \(-38\)  mm to \(-12\) and \(-13\)  mm, respectively. Our results show that remaining SLR biases depend on the satellite type and the use of coated or uncoated retro-reflectors. For Earth rotation parameters, the increasing number of GLONASS satellites and tracking stations over the past few years leads to differences between GPS-only and GPS+GLONASS combined solutions which are most pronounced in the pole rate estimates with maximum 0.2 mas/day in magnitude. At the same time, the difference between GLONASS-only and combined solutions decreases. Derived GNSS orbits are used to estimate combined GPS+GLONASS satellite clocks, with first results presented in this paper. Phase observation residuals from a precise point positioning are at the level of 2 mm and particularly reveal poorly modeled yaw maneuver periods.  相似文献   

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