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Orbit determination and prediction for Beidou GEO satellites at the time of the spring/autumn equinox

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Science China(Physics,Mechanics & Astronomy) 2015年第8期58卷 86-94页

作者： LI XiaoJie ZHOU Jianhua hu xiaogong LIU Li GUO Rui ZHOU ShanShi Beijing Satellite Navigation Center Shanghai Key Laboratory of Space Navigation and Position Techniques Shanghai Astronomical Observatory Chinese Academy of Sciences

Geostationary(GEO) satellites form an indispensable component of the constellation of Beidou navigation system(BDS). The ephemerides, or predicted orbits of these GEO satellites(GEOs), are broadcast to positioning, navigation, and timing users. User equivalent ranging error(UERE) based on broadcast message is better than 1.5 m(root formal errors: RMS) for GEO satellites. However, monitoring of UERE indicates that the orbital prediction precision is significantly degraded when the Sun is close to the Earth's equatorial plane(or near spring or autumn Equinox). Error source analysis shows that the complicated solar radiation pressure on satellite buses and the simple box-wing model maybe the major contributor to the deterioration of orbital precision. With the aid of BDS' two-way frequency and time transfer between the GEOs and Beidou time(BDT, that is maintained at the master control station), we propose a new orbit determination strategy, namely three-step approach of the multi-satellite precise orbit determination(MPOD). Pseudo-range(carrier phase) data are transformed to geometric range(biased geometric range) data without clock offsets; and reasonable empirical acceleration parameters are estimated along with orbital elements to account for the error in solar radiation pressure modeling. Experiments with Beidou data show that using the proposed approach, the GEOs' UERE when near the autumn Equinox of 2012 can be improved to 1.3 m from 2.5 m(RMS), and the probability of user equivalent range error(UERE)<2.0 m can be improved from 50% to above 85%.

关键词： Beidou system (BDS) Beidou time (BDT) geostationary (GEO) satellite spring equinox/autumn equinox solar radia-tion pressure time synchronization user equivalent ranging error

Signal-in-space accuracy for BeiDou navigation satellite system:Challenges and solutions

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Science China(Physics,Mechanics & Astronomy) 2017年第1期60卷 84-86页

作者： ShanShi Zhou Bin Wu xiaogong hu YueLing Cao Yang Yu Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China

Service accuracy of global navigation satellite system （GNSS） is determined by satellite constellation, sig- nal-in-space （SIS） accuracy and signal transmission errors. The State Council Information Office of the People＇s Repub- lic of China issued China＇s BeiDou Navigation Satellite Sys- tem （BDS） White Paper （***/***） on Jun. 16th 2016, which notes that, BDS takes a three-step development strategy, from domestic service, through Asia-Pacific regional service, to global service, and features mixed constellation of Geostationary Earth Orbit （GEO）, Inclined Geostationary Earth Orbit （IGSO） and Medium Earth Orbit （MEO） satellites.

关键词： navigation constellation Medium notes GNSS issued Republic

Mars Express tracking and orbit determination trials with Chinese VLBI network

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Chinese Science Bulletin 2010年第32期55卷 3654-3660页

作者： CAO JianFeng huANG Yong hu xiaogong MA maoLi ZHENG WeiMin Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China Graduate University of Chinese Academy of Sciences Beijing 100049 China Beijing Aerospace Control and Command Center Beijing 100094 China

With strong support from European Space Agency (ESA),Shanghai Astronomical Observatory (SHAO) organized a tracking and orbit determination trails using Chinese VLBI Network (CVN) to track Mars Express,the first Mars probe launched by ESA. Using a high-resolution VLBI software correlator and Doppler measurement system developed in-house,two sets of tracking data,VLBI and Doppler,were acquired. The trials represent the first successful foray held in China to track a probe about 360 million kilometers away from the Earth. The tracking data are analyzed using a Mars satellite orbit determination software system developed at SHAO. The results show that the accuracy of 5 s integrated three-way-Doppler data is about 0.3 mm/s,or roughly the same accuracy as ESA's tracking data. Position discrepancies between the Doppler-based orbit solution of 8 h arc-length (about 1 orbital revolution) and ESA's reconstructed orbit are of the order of several hundred meters. In preparing for the Russia-China co-sponsored Mars exploration mission Phobos-Grunt-Yinghuo,simulations were carried out to evaluate the achievable orbital accuracy levels and the contributions of VLBI and Doppler data respectively. Results show that Doppler data provide better orbit accuracy,so that for VLBI to be able to provide kilometer level orbit solutions,the accuracy of VLBI measurement needs to be improved by at least one order of magnitude.

关键词： VLBI技术火星探测器跟踪调查卫星定轨观测网中国试验轨道测定

Precise absolute positioning for a single-frequency user

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Science China(Physics,Mechanics & Astronomy) 2013年第8期56卷 1591-1597页

作者： LI HaoJun TANG GuiFeng HE Feng WU Bin hu xiaogong CHEN YanLing Shanghai Astronomical Observatory Chinese Academy of Sciences Guangxi Key Laboratory of Spatial Information and Geomatics Guilin University of Technology Shanghai Key Laboratory of Space Navigation and Position Techniques Beijing Satellite Navigation Center

A new strategy to realize precise absolute positioning for a single-frequency user is presented. In the presented strategy, the receiver clock and ambiguities are removed using the satelliteand epoch-differenced (SDED) algorithm. As a further development of the SDED algorithm, a regional augmentation network is used to generate the SDED atmospheric delays at the user. The weakened mathematic property due to the epoch-differenced operation is improved by adding the generated atmospheric delays and applying the robust estimation. To test the new approach, the 24-h data at 5 Continuous Operation Reference Station (CORS) stations in Shanghai is processed. The results show a more than 96% success rate, defined as the case where three directions achieve the desired positioning accuracy of 10 cm, when the observation is longer than 20 min. The 20-min static results show that the new method can reach an accuracy of 3.42, 4.76 and 9.26 cm in the North, East and Up directions, respectively. An experiment was carried out to assess the kinematic positioning. The results show that the kinematic positioning accuracy is 4.11, 5.31 and 4.05 cm in the north-south, east-west and height directions,respectively.

关键词： absolute positioning single-frequency user correction information

Inter-satellite link augmented BeiDou-3 orbit determination for precise point positioning

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Chinese Journal of Aeronautics 2022年第4期35卷 332-343页

作者： Liqian ZHAO xiaogong hu Chengpan TANG Shanshi ZHOU Yueling CAO Qianxin WANG Ranran SU Space Star Technology Co. Ltd.Beijing 100095China Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China School of Environment Science and Spatial Informatics China University of Mining and TechnologyXuzhou 221116China Beijing Satellite Navigation Center Beijing 100094China

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) payload, which can track the whole arc of the BeiDou-3 satellites and enhance the orbit determination accuracy with regional ground stations. In this contribution, a novel orbit determination strategy for BeiDou-3 PPP is proposed, in which the BeiDou-3 satellite orbits are enhanced by the ISL. First, the generation of precise satellite products is demonstrated in *** addition, the products are assessed by Satellite Laser Ranging(SLR) residuals and overlap comparisons. Moreover, the products are used for receivers in China's Mainland to carry out the static and kinematic modes to research the PPP performance of Bei Dou-3’s 3IGSO/24MEO *** SLR validations of the satellite orbits demonstrate an accuracy better than 0.1 m in the radial component, and the orbit overlap comparisons show accuracies of 0.016 m in the radial component,0.088 m in the along-track component and 0.087 m in the cross-track component. The Standard Deviation(STD) in the differences in overlapping arcs for the estimated satellite clocks is approximately 0.10 ns. The static PPP results demonstrate that the error in both the horizontal and vertical components is smaller than 10 cm after 30 minutes of convergence. After 24 hours of convergence,the errors are 0.70 cm, 0.63 cm and 1.99 cm for the north, east and up components, *** kinematic PPP experiment illustrates that the Root Mean Square(RMS) position errors in the north, east and up components are approximately 3.23 cm, 5.27 cm a

关键词： BeiDou-3 Clock offsets Convergence Inter-satellite link Precise Point Positioning Regional ground stations Satellite orbits

Research on High Accuracy Prediction Model of Satellite Clock Bias

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Research on High Accuracy Prediction Model of Satellite Cloc...

Precise orbit determination for geostationary satellites with multiple tracking techniques

第五届中国卫星导航学术年会

作者： XU Xueqing hu xiaogong ZHOU Yonghong SONG Yezhi Shanghai Astronomical Observatory Chinese Academy of sciences

ISBN: (纸本)9783642547393

Time basis of satellite navigation system is achieved by the satellite clock bias （SCB） prediction, while the SCB prediction accuracy will also affect the positioning accuracy of real‐time navigation users. With the development of our Beidou satellite navigation system, the accuracy requirements of the SCB prediction is higher and higher, general quadratic polynomial extrapolation method have failed to meet the SCB forecast accuracy for each satellite. There is an urgent need to develop the SCB prediction program for each satellite, here we use a combined method of least squares and auto‐regressive model （LS+AR） from the EOP forecasting, to predict and assess SCB with data from IGS. Results show that the combined LS+AR method can improve the SCB forecast accuracy effectively.

关键词： SCB prediction least squares auto-regressive model

来源： cnki会议评论

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Chinese Science Bulletin 2010年第8期55卷 687-692页

作者： GUO Rui hu xiaogong TANG Bo huANG Yong LIU Li CHENG LiuCheng HE Feng Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China Graduate University of Chinese Academy of Sciences Beijing 100039 China Beijing Global Information Application and Development Center Beijing 100094 China

A new precise orbit determination (POD) strategy based on the combination of satellite laser ranging (SLR) and C-band transfer ranging for geostationary satellites (GEO) is *** approaches to calibrate ranging biases of the C-band ranging system are proposed,namely the two tracking system co-location comparison and the combined POD method,with calibration accuracies estimated to be 0.5 ns and 1 ns *** data from a C-band tracking network in China,POD experiments indicate that meter-level POD accuracy is achievable for ***-mean-square (RMS) of the post-fit C-band ranging data is about 0.205 *** radial component errors of POD are evaluated with SLR data from a station in Beijing,with residual RMS of 0.133 *** overlapping experiments show the total orbit error is a few *** of SLR residuals also suggest that for 2-hour prediction,the predicted radial error is about 0.373 m.

关键词：地球静止卫星卫星轨道确定跟踪系统过氧化物酶技术校准精度地球同步轨道激光测距

Multipath error detection and correction for GEO/IGSO satellites

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Science China(Physics,Mechanics & Astronomy) 2012年第7期55卷 1297-1306页

作者： WU XiaoLi ZHOU Jianhua WANG Gang hu xiaogong CAO YueLing Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030China Beijing Global Information Application and Development Center Beijing 100094China

Constellations of regional satellite navigation systems are usually constituted of geostationary satellites (GEO) and inclined geostationary satellites (IGSO) for better service availability. Analysis of real data shows that the pseudorange measurements of these two types of satellites contain significant multipath errors and code noise, and the multipath for GEO is extremely serious, which is harmful to system services. In contrast, multipath error of carrier phase measurements is less than 3 cm, which is smaller than the multipath of pseudorange measurements by two orders of magnitude. Using a particular combination of pseudorange and dual-frequency carrier phase measurements, the pseudorange multipath errors are detected, and their time varying features are analyzed. A real-time multipath correction algorithm is proposed in this paper, which is called CNMC (Code Noise and Multipath Correction). The algorithm decreases the influence of the multipath error and therefore ensures the performance of the system. Data processing experiments show that the multipath error level may be reduced from 0.5 m to 0.15 m by using this algorithm, and 60% of GEO multipath errors and 42% of IGSO multipath errors are successfully corrected with CNMC. Positioning experiments are performed with a constellation of 3 GEO plus 3 IGSO satellites. For dual-frequency users the East-West position accuracy is improved from 1.31 m to 0.94 m by using the CNMC algorithm, the South-North position accuracy is improved from 2.62 m to 2.29 m, and the vertical position accuracy is improved from 4.25 m to 3.05 m. After correcting multipath errors, the three-dimensional position accuracy is improved from 5.16 m to 3.94 m.

关键词： multipath error carrier smoothing pseudorange GEO satellite position error

Satellite-station time synchronization information based real-time orbit error monitoring and correction of navigation satellite in Beidou System

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Science China(Physics,Mechanics & Astronomy) 2014年第7期57卷 1395-1403页

作者： HE Feng ZHOU ShanShi hu xiaogong ZHOU Jianhua LIU Li GUO Rui LI XiaoJie WU Shan Shanghai Astronomical Observatory Chinese Academy of Sciences Graduate University of Chinese Academy of Sciences Beijing Satellite Navigation Center

Satellite-station two-way time comparison is a typical design in Beidou System(BDS)which is significantly different from other satellite navigation *** a type of two-way time comparison method,BDS time synchronization is hardly influenced by satellite orbit error,atmosphere delay,tracking station coordinate error and measurement model ***,single-way time comparison can be realized through the method of Multi-satellite Precision Orbit Determination(MPOD)with pseudo-range and carrier phase of monitor *** is proved in the constellation of 3GEO/2IGSO that the radial orbit error can be reflected in the difference between two-way time comparison and single-way time comparison,and that may lead to a substitute for orbit evaluation by *** this article,the relation between orbit error and difference of two-way and single-way time comparison is illustrated based on the whole constellation of *** the all-weather and real-time operation mode of two-way time comparison,the orbit error could be quantifiably monitored in a real-time mode through comparing two-way and single-way time *** addition,the orbit error can be predicted and corrected in a short time based on its periodic *** is described in the experiments of GEO and IGSO that the prediction accuracy of space signal can be obviously improved when the prediction orbit error is sent to the users through navigation message,and then the UERE including terminal error can be reduced from 0.1 m to 0.4 m while the average accuracy can be improved more than 27%.Though it is still hard to make accuracy improvement for Precision Orbit Determination(POD)and orbit prediction because of the confined tracking net and the difficulties in dynamic model optimization,in this paper,a practical method for orbit accuracy improvement is proposed based on two-way time comparison which can result in the reflection of orbit error.

关键词： satellite navigation orbital mechanics time synchronization ephemeris fitting