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Zheng Zuoya,Huang Cheng,Lu Xiushan,

大地测量与地球动力学 , 2007,
Abstract: On the basis of the theory of on-board GPS precise orbit determination (POD), having analyzed and discussed functional model and stochastic model of on-board GPS low earth orbit (LEO) satellite, the linear combination, zero-differential and differential functional model form and their advantages and disadvantages are put forward. According to different ideas and models for solution,some methods for orbit determinations: one-step POD, two-step POD, dynamic POD, reduced-dynamic POD, geometry POD and kinematic POD are analyzed. Finally, the on-board GPS geometry-dynamic POD method and its prospective are discussed.
jason-2卫星星载gps数据cm级精密定轨  [PDF]
武汉大学学报(信息科学版) , 2014,
Abstract: ?目的jason-2卫星为测高卫星,需要cm级的轨道精度。利用jason-2星载gps数据,采用简化动力学法进行了jason-2卫星精密定轨。对简化动力学轨道进行重叠轨道对比,径向精度达到1.19cm;与class提供的poe结果对比,径向精度达到5.54cm;与slr数据进行对比,整体精度达到6.63cm。因此,简化动力学轨道达到了cm级要求,定轨精度良好。
Zero-difference and single-difference precise orbit determination for LEO using GPS
DongJu Peng,Bin Wu
Chinese Science Bulletin , 2007, DOI: 10.1007/s11434-007-0264-3
Abstract: Various methods for precise orbit determination (POD) of low earth orbiters (LEO) are briefly introduced in this paper. Based on the software named SHORD-III developed by our institute, single-difference (SD) and zero-difference (ZD) dynamic POD based on LEO carrying an on-board GPS receiver is mainly discussed. The approaches are tested using real GRACE data (November 5–25, 2002) and independently validated with Satellite Laser Ranging (SLR) measurements over the same 21 days. Comparisons with the scientific orbits provided by GFZ indicate that the SD POD RMS accuracy can achieve 5, 10 and 6 cm in radial, along and cross the track, and the ZD POD RMS accuracy can achieve 4, 8 and 4 cm in radial, along and cross the track. SLR validation shows that SD POD accuracy is better than 8 cm in distance, and ZD POD accuracy is better than 6 cm.

Kuang Cuilin,Liu Jingnan,Zhao Qile,

大地测量与地球动力学 , 2009,
Abstract: The combined orbit determination method for low earth orbit satellite and GPS satellite using ground-and space-based GPS tracking data is studied.Some tests were designed according to different number and distribution of ground GPS tracking stations and implemented by use of PANDA(Positioning And Navigation Data Analysis) software.Numerical results show that better orbit precision with the method can be obtained as compared to "two-step orbit determination method",because this method profits from the low ea...
JASON-2天线相位中心变化估计及1cm精密轨道确定  [PDF]
大地测量与地球动力学 , 2015, DOI: 10.14075/j.jgg.2015.02.002
Abstract: ?利用JASON\|2卫星1a的实测星载GPS数据,基于非差简化动力学定轨残差,建立JASON\|2接收机天线相位中心变化(PCV)模型。采用一个轨道重复周期的独立数据,分析JASON\|2的PCV对定轨残差和定轨精度的影响。引入所得PCV确定JASON\|2的1a的最终精密轨道,通过残差分析、重叠弧段对比以及与JPL外部精密轨道比较等方式对轨道精度进行评价,结果表明,所得PCV能够提升JASON\|2卫星精密轨道精度且结果比较稳定,可以实现3DRMS接近2.5cm、径向RMS约1.0cm的定轨精度。
An Improved Model for Single-Frequency GPS/GALILEO Precise Point Positioning  [PDF]
Akram Afifi, Ahmed El-Rabbany
Positioning (POS) , 2015, DOI: 10.4236/pos.2015.62002
Abstract: This paper introduces a new precise point positioning (PPP) model, which combines single-fre- quency GPS/Galileo observations in between-satellite single-difference (BSSD) mode. In the absence of multipath, all receiver-related errors and biases are cancelled out when forming BSSD for a specific constellation. This leaves the satellite originating errors and atmospheric delays un- modelled. Combining GPS and Galileo observables introduces additional biases that have to be modelled, including the GPS to Galileo time offset (GGTO) and the inter-system bias. This paper models all PPP errors rigorously to improve the single-frequency GPS/Galileo PPP solution. GPSPace PPP software of Natural Resources Canada (NRCan) is modified to enable a GPS/Galileo PPP solution and to handle the newly introduced biases. A total of 12 data sets representing the GPS/Galileo measurements of six IGS-MEGX stations are processed to verify the newly developed PPP model. Precise satellite orbit and clock corrections from IGS-MEGX networks are used for both GPS and Galileo measurements. It is shown that sub-decimeter level accuracy is possible with single-frequency GPS/Galileo PPP. In addition, the PPP solution convergence time is improved from approximately 100 minutes for the un-differenced single-frequency GPS/Galileo solution to approximately 65 minutes for the BSSD counterpart when a single reference satellite is used. Moreover, an improvement in the PPP solution convergence time of 35% and 15% is obtained when one and two reference satellites are used, respectively.
Jason-1卫星厘米级星载GPS精密定轨  [PDF]
科学通报 , 2008,
Abstract: 美法合作研制的Jason-1海洋卫星于2001年2月7日在美国加利福尼亚州成功发射,它接替已经运行了9年的Topex/Poseidon(T/P)卫星,继续对全球海平面进行高精度的实时监测.海洋卫星的轨道误差,尤其是径向误差直接影响卫星测高的效果,为了能与T/P的测高数据很好地衔接,Jason-1卫星径向轨道须达到2.5cm精度.本文利用Jason-1卫星星载GPS实测数据,通过非差动力学定轨方法,计算了Jason-1卫星2002年12月19日至2003年1月7日两个cycle的轨道,并利用与JPL计算的精密轨道比较、轨道重叠检验及SLR检核等多种方法全面地分析了本文的定轨结果.多种比较结果综合表明,Jason-1卫星径向定轨精度可达到1~2cm.
Real-Time GPS/Galileo Precise Point Positioning Using NAVCAST Real-Time Corrections  [PDF]
Abdelsatar Elmezayen, Ahmed El-Rabbany
Positioning (POS) , 2019, DOI: 10.4236/pos.2019.103003
Abstract: Real-time precise point positioning (PPP) is possible through the use of real-time precise satellite orbit and clock corrections, which are available through a number of organizations including the International GNSS Service (IGS) real-time service (IGS-RTS). Unfortunately, IGS-RTS is only available for the GPS and GLONASS constellations. In 2018, a new real-time service, NAVCAST, which provides real-time precise orbit and clock corrections for the GPS and Galileo constellations, was launched. In this research, the potential performance of real-time PPP which makes use of NAVCAST real-time corrections is analyzed using various static and kinematic datasets. In the static dataset, 24 hours of observations from eight IGS stations in Canada over three different days were utilized. The static results show that the contribution of Galileo satellites can improve the positioning accuracy, with 30%, 34%, and 31% in east, north, and up directions compared to the GPS-only counterparts. In addition, centimeter-level positioning accuracy in the horizontal direction and decimeter-level positioning accuracy in the vertical direction can be achieved by adding Galileo observations. In the kinematic dataset, a real vehicular test was conducted in urban and suburban combined areas. The real-time kinematic GPS/Galileo PPP solutions demonstrate an improvement of about 53%, 45%, and 70% in east, north, and up directions compared to the GPS-only counterparts. It is shown that the real-time GPS/Galileo PPP can achieve a sub-decimeter horizontal positioning accuracy and about meter-level vertical positioning accuracy through the use of NAVCAST real-time corrections.
Improved Between-Satellite Single-Difference Precise Point Positioning Model Using Triple GNSS Constellations: GPS, Galileo, and BeiDou  [PDF]
Akram Afifi, Ahmed El-Rabbany
Positioning (POS) , 2016, DOI: 10.4236/pos.2016.72006
Abstract: This paper introduces a new dual-frequency precise point positioning (PPP) model, which combines the observations of three different GNSS constellations, namely GPS, Galileo, and BeiDou. Our model is based on between-satellite single-difference (BSSD) linear combination, which cancels out some receiver-related biases, including receiver clock error and non-zero initial phase bias of the receiver oscillator. The reference satellite can be selected from any satellite system GPS, Galileo, and BeiDou when forming BSSD linear combinations. Natural Resources Canada’s GPS Pace PPP software is modified to enable a combined GPS, Galileo, and BeiDou PPP solution and to handle the newly introduced biases. A total of four data sets at four IGS stations are processed to verify the developed PPP model. Precise satellite orbit and clock products from the IGS-MGEX network are used to correct both of the GPS and Galileo measurements. It is shown that using the BSSD linear combinations improves the precision of the estimated parameters by about 25% compared with the GPS-only PPP solution. Additionally, the solution convergence time is reduced to 10 minutes for both BSSD scenarios, which represent about 50% improvement in comparison with the GPS-only PPP solution.
Performance of Open Source Precise Point Positioning Software Using Single-Frequency GPS Data
Chalermchon Satirapod, Somchai Kriengkraiwasin
Artificial Satellites , 2006, DOI: 10.2478/v10018-007-0008-2
Abstract: This research aims to assess the performance of GPS Precise Point Positioning (PPP) with code and carrier phase observations from L1 signal collected from geodetic GPS receiver around the world. A simple PPP software developed for processing the single frequency GPS data is used as a main tool to assess a positioning accuracy. The precise orbit and precise satellite clock corrections were introduced into the software to reduce the orbit and satellite clock errors, while ionosphere-free code and phase observations were constructed to mitigate the ionospheric delay. The remaining errors (i.e. receiver clock error, ambiguity term) are estimated using Extended Kalman Filter technique. The data retrieved from 5 IGS stations located in different countries were used in this study. In addition, three different periods of data were downloaded for each station. The obtained data were then cut into 5-min, 10-min, 15-min and 30-min data segments, and each data segment was individually processed with the developed PPP software to produce final coordinates. Results indicate that the use of 5-min data span can provide a horizontal positioning accuracy at the same level as a pseudorange-based differential GPS technique. Furthermore, results confirm effects of station location and seasonal variation on obtainable accuracies.
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