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第三届中国卫星导航学术年会

作者： Xinming Huang,Hang Gong,Wenke Yang,Xiangwei Zhu,Gang Ou satellite Navigation R&D Center,National Univ.of Defense Technology,Changsha 410073,China

As a core part of satellite payload,satellite clock has a direct influence on GNSS service ***,it is necessary to monitor its integrity. In this paper,real-time test statistics for satellite clock phase and frequency anomaly are built,and an integrity monitoring algorithm for satellite clock based on these statistics is *** is composed of two parts,including phase anomaly monitoring and frequency anomaly monitoring,which mainly aims at three anomalies comprising occasional bad or outlier points,anomaly jumps that later return to stable values and phase or frequency *** new algorithm can not only detect phase and frequency anomalies,but also identify and deal with clock anomaly instantly,including eliminating and replacing the anomaly data. satellite clock anomalies are simulated using the IGS observation clock data and performance of the new algorithm is *** results show that the new algorithm has a perfect performance of detecting the satellite clock anomaly including both phase anomaly and frequency *** the same time,it can also eliminate and replace the anomaly data,and the replaced error is negligible. The integrity monitoring algorithm for satellite clock proposed in this paper is helpful to GNSS satellite clock autonomous integrity monitoring.

关键词： satellite clock Phase Anomaly Frequency Anomaly Test statistic Real-time anomaly detection Integrity monitoring

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The exploration of satellite clock and ephemeris error correction in wide area differential system

The exploration of satellite clock and ephemeris error corre...

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第三届中国卫星导航学术年会

作者： ChengLin CAI 1* XiaoHui LI 2 &HaiTao WU 3 1.Guilin University of Electronic Technology,541004,Guilin,China 2.National Time Service Center,Chinese Academy of Sciences,710600,Lintong,China 3.Academy of Opto-Electronics,Chinese Academy of Sciences,100094,Beijing,China

Real time principle of wide area differential GPS(WADGPS)uses a generally inverted positioning method of four-dimensional solution of satellite clock and ephemeris *** with the real time single point positioning,positioning accuracy of this method is improved greatly,but the DOP of four-dimensional calculation is up to several hundred,under the error amplification effect of DOP,1 m positioning precision level of WADGPS is difficult to *** overcome the limit of DOP,the feasibility on large and small part decomposition of satellite clock and ephemeris error is analyzed, and optimal differential performances of the exploring two smallness correction methods:Small DOP and no DOP constraint,are analyzed,and they will be the foundation for further exploration.

关键词： wide area differential GPS(WADGPS) DOP satellite clock ephemeris

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Analysis of BDS satellite clock Prediction Contribution to Rapid Orbit Recovery

Analysis of BDS Satellite Clock Prediction Contribution to R...

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第九届中国卫星导航学术年会

作者： Qian Chen Junping Chen Yize Zhang Shan WU Xiuqiang Gong Shanghai Astronomical Observatory Chinese Academy of Sciences School of Astronomy and Space Science University of Chinses Academy of Sciences

The BDS-2 system is designed as a GEO/IGSO/MEO mixed ***,there exists satellite maintaining operation for GEO or IGSO satellite every 7 to 10 *** this period the maneuver satellite is out of *** will be about 5 to 6 hours starting from the beginning of satellite maneuver to the release of the first group of recovery *** of satellite clock assisted precise orbit determination(POD) is normally implement,where the most critical factor that contributes to the availability of maneuver satellites is the length of accumulation of ***,the last hour of real-time observed pseudo-range data of tracking station could not be included in POD,due to the reason that the satellite clock could not be observed in real-time..In this paper,we propose to use the polynomial fitting method to forecast the satellite clocks and use it in *** analyze the accuracy of satellite clocks prediction and its contribution to the rapid orbit *** show that the satellite unavailability time could be shortened by at least 1 hour,which effectively improves satellite *** it improves the accuracy of orbit determination and prediction by more than 15% and 70%.

关键词： BDS Time Synchronization satellite clock Precise Orbit Determination Rapid Orbit Recovery satellite Availability

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Performance Assessment of Galileo In-Orbit satellite clocks

Performance Assessment of Galileo In-Orbit Satellite Clocks

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第七届中国卫星导航学术年会

作者： YU Bi-yun ZHANG Hui-jun LI Xiao-hui National Time Service Center CAS Key Laboratory of Precision Navigation Positioning and Timing CAS University of Chinese Academy of Scineces

At present,the Galileo in-orbit satellites include four IOV（In-Orbit Validation）satellites and eight FOC（Full Operational Capability）satellites. The accuracy of Galileo positioning is better than 2 meters.30 FOC satellites are expected to be launched completely by 2019, and a complete constellation of full operational capability will be achieved by the time. The quality of Galileo satellite clock affects the performance of navigation and reliability. Based on this,a solution of satellite clock assessment is given, the standard time and frequency signal of National time service center of Chinese Academy of Sciences is taken as a reference. The performance of all Galileo in-orbit satellites clocks is assessed by receiving the signal in space and using the way of dual-frequency ionosphere-free combination, which include frequency deviation, frequency drift, frequency stability and the consistency of the frequency stability over time. At the same time, the uncertainty of relative frequency, frequency stability and time offset of Galileo satellites clocks is analyzed. The evaluation results show that the orbit satellite clock frequency stability is（? =60s and? =300s） at e-13 level, the uncertainty of frequency stability is in the order of e-14, and the stability is consistent over time. When the satellite clock time is corrected to the Galileo system time（GST）,the time offset of GST relative to UTC（NTSC） is between-40 ns and-70 ns., and the satellite clock stability after clock correction is slightly improved. The uncertainty of measurement of system time offset is 3.37 ns. Research methods and achievements of this paper can be the significant references with respect to Galileo stand-alone positioning, multi-GNSS combination positioning, Integrity monitoring, the Galileo system time interoperability, etc

关键词： Galileo satellite clock assessment stability uncertainty

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Performances assessments for GNSS/BDS-3 satellites on-board clock with long-term iGMAS products

Performances assessments for GNSS/BDS-3 satellites on-board ...

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第十三届中国卫星导航年会

作者： Changzhong Ma Qianxin Wang Cheng Tong Chao Hu NASG Key Laboratory of Land Environment and Disaster Monitoring China University of Mining and Technology School of Environment Science and Spatial Informatics China University of Mining and Technology School of Geomatics Anhui University of Science and Technology

After officially announced the service of BDS-3 system, the promotion and industrial application of BDS-3 is a new highland for BeiDou innovation and development. satellites’ performances are one of prerequisite for high-accuracy and high-reliability location-based services, in which the atomic clock is playing an important role as the main technology advantage. In order to evaluate the reliability of GNSS and BDS-3 on-orbit atomic clock, this paper compared and analyzed the main technical indicators of the on-board atomic clock based on the GNSS satellite product sequence accumulated by iGMAS Analysis Center. Firstly,using GNSS and BDS-3 satellite clock offset products of 5 years and 2 years respectively, the clock offset performance of each system is analyzed from the aspects of phase, frequency, frequency drift and fitting residuals. Then, the overlapping Hadamard variance is used to evaluate the stability of the atomic clocks. The results indicate that: 1) the continuities of GPS, GLONASS, Galileo and BDS-2 on-board are poor during 2015-2017, in which the phase jumps are relatively obvious. After 2008, the qualities of phase data are improved with fewer modulation operations. Meanwhile, BDS-3 presents a better continuous and highquality clock for 2019-2020 with less phase-modulation operation. 2) the frequency drift values of GPS, GLONASS, Galileo and BDS-3 satellite clocks are all in the order of 10-19, while the frequency drift values of BDS-2 satellite clocks are in the order of 10-18. In terms of the overall variation trend, the frequency drift of GPS, GLONASS and BDS-2 systems is relatively stable, while the frequency drift of Galileo and BDS-3 systems presents an obvious segmentation phenomenon. The frequency drift of satellite clock of BDS-3 system will increase by one order in 2020 compared with that of 2019, reaching the order of 10-20. 3)the RMS of fitting clock models for GPS, GLONASS, Galileo, BDS-2(GEO/IGSO/MEO) and BDS-3 are 0.62 ns, 0.72 ns, 0.99

关键词： GNSS/BDS-3 satellite clock Performances assessments Long-term products iGMAS

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satellite Integrity Autonomous Monitoring(SAIM) of BDS and Onboard Performance Evaluation

Satellite Integrity Autonomous Monitoring(SAIM) of BDS and O...

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第九届中国卫星导航学术年会

作者： Lang Bian Wenshan Liu Tao Yan Yueling Cao Rui Li Wei Wang Xiao Liu Wenyin Lei Yansong Meng Lixin Zhang China Academy of Space Technology (Xi’an) Shanghai Astronomical Observatory Beihang University

With the development of satellite navigation technology,the users’demands for the integrity of GNSS are more and more *** ground based monitoring system can hardly report an alarm message to the GNSS users during the valid alarming period due to the satellite-earth propagation *** is beneficial to monitor the abnormal events and report the corresponding alarms in *** this way,which is an important branch of the future GNSS integrity monitoring,the time needed to give an alarm is shorter and the capability of system integrity service is strengthened.A new generation of BDS satellites has the capable of satellite autonomous integrity monitoring(SAIM).This paper presents the technology scheme of SAIM,and proposes the integrity monitoring method of navigation signals and clock *** proposed method is verified based on the onboard test of the IGSO *** addition,we analyze the integrity telemetry data from the new generation of BDS satellite,including the signal delay,power,carrier phase measurement,correlation peak,consistency of pseudo-code and carrier phase,clock phase and frequency *** analysis results indicate that the quality of the data on orbit meets the requirements,and SAIM could monitor effectively the abnormal change of satellite clock and navigation signal,generate rapidly the alarm message,and transmit them to *** alarm time is less than 6 seconds through the message,and 2 seconds through the non-standard code(NSC).In the end,we present the future work for improving the SAIM technology of BDS.

关键词： SAIM Navigation Signal satellite clock

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satellite Autonomous Integrity Monitoring of BDS and Onboard Performance Evaluation

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Aerospace China 2020年第4期21卷 42-49页

作者： BIAN Lang LIU Xiao LIU Wenshan YAN Tao LEI Wenying JIA Yizhe MENG Yansong ZHANG Lixin China Academy of Space Technology(Xi’an) Xi’an 710100

With the development of satellite navigation technology,the user demands for the integrity of Global Navigation satellite System(GNSS)have increased more and more.A ground-based monitoring system can hardly report an alarm message to GNSS users during the valid alarming period due to the satellite-Earth propagation *** is beneficial to monitor abnormal events and report the corresponding alarms from *** this approach,which is an important feature for future GNSS integrity monitoring,the time needed to provide an alarm is shorter and the system integrity capability is *** BeiDou Navigation satellite System(BDS)new generation satellites have the capabilities of satellite autonomous integrity monitoring(SAIM).This paper presents the technical scheme of SAIM,and proposes the integrity monitoring method of both navigation signals and the clocks *** proposed method was verified through the onboard test on the BDS *** addition,we analyzed the integrity telemetry data from the new generation of BDS satellite,including signal delay,power,carrier phase measurement,correlation peak,consistency of pseudo-code and carrier phase,clock phase and frequency *** analysis results indicated that the quality of the data on orbit met the requirements,and SAIM could monitor effectively any abnormal change of satellite clocks and navigation signal,generate rapidly an alarm message,and transmit it to the *** alarm time was less than 6 s through the message,and 2 s through non-standard code(NSC).Finally,we present future opportunities for improving the SAIM technology of BDS.

关键词： SAIM navigation signal satellite clock

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