全球定位系统

2019 Vol. 44, No. 5

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Fog positioning and its applications

SHI Chuang, GU Shengfeng, JING Guifei, GENG Jianghui, LOU Yidong, TANG Weiming

2019, 44(5): 1-9. doi: DOI:10.13442/j.gnss.1008-9268.2019.05.001

[Abstract](1491) [PDF 1146KB](974)

Abstract:
With the development of GNSS, the LBS (Location Based Service) has been popularized rapidly. Meanwhile, people’s demand for PNT service with high reliability, high credibility and high precision is increasingly urgent. PNT is a system which integrates multi-technology and multilevel systems. Focusing on the optimization of PNT service, domestic and overseas scholars have put forward several new architectures and technical systems such as All Source Positioning and Navigation, Resilient PNT and Cloud Positioning. This study states, that with heterogeneous positioning resources which are capable in communication, calculation, storing, positioning and sensing as infrastructure construction, PNT service with high reliability, high credibility and high precision can be realized by intelligent management and scheduling of heterogeneous positioning resources distributed in different geolocations. Further, the definitions of Fog Positioning and Omnipresent Positioning and Navigation are given. It is argued that the definition of Fog Positioning is evolved from distributed computing architecture and emphasizes the architecture for PNT service. While the definition of Omnipresent Positioning and Navigation is evolved from the development of positioning technology and emphasizes the ability to realize omnipresent positioning by collaborative fusion processing of omnipresent positioning resources. On this basis, by comparing Fog Positioning with Cloud Positioning, this study points out that Fog Positioning is the extension of Cloud Positioning towards the user side and the omnipresent realization of positioning resources. Meanwhile, Fog Positioning is one kind of dynamic and elastic cloud, so Fog Positioning can be seen as a PNT architecture with the property of elasticity. Omnipresent positioning is an important target of PNT architecture, and Fog Positioning gives the potential means for this target, e.g., Omnipresent Positioning and Navigation. At last, this contribution analysis the basic service mode for Fog Positioning or Omnipresent Positioning and Navigation under the city environment and indoor environment.

Research on narrow-band interference suppression in BDS signal for reducing useful signal loss

DING Jicheng, WANG Yifang, LUO Zhibin

2019, 44(5): 10-17. doi: DOI:10.13442/j.gnss.1008-9268.2019.05.002

[Abstract](421) [PDF 992KB](96)

Abstract:
The key to narrow-band interference suppression is to suppress the interference while minimizing the loss of useful signals. Based on the time-frequency domain combined interference suppression method, and the completion of frequency domain interference parameter detection, this paper focuses on the key part of the interference suppression effect and useful signal loss-the design of the IIR notch filter. Based on the principle of zero-pole configuration, through theoretical research and detailed derivation analysis, it is proposed that by adding a pair of zero-poles and combining theoretical calculation to determine the polar angle and radius, the notch filter can obtain steeper band-stop characteristics on the premise of controllable pass-band gain and symmetrical transition band, which can theoretically reduce its usefulness. Compared with the current mainstream time-domain LMS algorithm, FFT-based frequency-domain-suppression algorithm and traditional time-frequency domain combination algorithm, simulation results show that the proposed method increases the peak-to-noise ratio by 53.47%, 8.369% and 5.907%, and the average output carrier-to-noise ratio by 5.147 2 dB and 2.003 7, and 0.508 6 dB respectively. More navigation signals are retained while effectively suppressing interference.

Application of robust estimation in RTK／INS tightly-coupled algorithms

CHU Chao, HUANG Liang, DU Zhongjin, YE Shirong

2019, 44(5): 18-25. doi: DOI:10.13442/j.gnss.1008-9268.2019.05.003

[Abstract](495) [PDF 915KB](153)

Abstract:
GNSS／INS navigation positioning results for dynamic environment are often affected by the gross error problem, a kind of GPS／BDS double system RTK／INS tightly-couplede integration algorithm based on robust kalman filter is proposed. According to variance expansion model, robust Kalman algorithm is established to obtain GNSS/INS tightly integrated robust solutions, and through two different regions. The experimental results show that the navigation accuracy of this method is improved by 1.4～4.6 cm, 0.7～9 cm, 1.5～2 cm, and the success rate of ambiguity fixing is increased by 10.3～25.6% compared with the traditional methods in three directions of N, E and D, respectively. The navigation accuracy and reliability of this method are improved significantly, and the vehicle navigation accuracy and reliability in dynamic environment are improved. The application of automatic driving has certain theoretical reference and practical value.

Mathematical model study and performance analysis ofBDS RTK／MEMS-INS integration

LIU Chongjin, GAO Zhouzheng, TU Rui, ZHANG Rui, HAN Junqiang, LU Xiaochun

2019, 44(5): 26-34. doi: DOI:10.13442/j.gnss.1008-9268.2019.05.004

[Abstract](471) [PDF 1062KB](123)

Abstract:
The satellite navigation system and inertial navigation system are highly complementary, the integration of the two systems can improve the usability, continuity and reliability effectively. With the rapid development of the BeiDou system and the continuous improvement of the performance of low-cost MEMS IMU, the study on the theory and technology of integrated navigation system based on BDS and low-cost IMU has strong research significance and practical value. Firstly, the theoretical model of BDS RTK/M-EMS INS is deduced, and the performance of the integrated system is analyzed using the measured vehicle data. The experimental results show that introducing low-cost IMU into BDS can effectively improve the precision of velocity measurement without losing the positioning precision. The positioning accuracy in the vehicle dynamics is mm level, and the RMS of velocity error improvement has reached to 75.8％, 79.5％, 66.7％ in the north, east, and vertical components respectively. Moreover, using dual-frequency data in the tightlycoupled integration of BDS+INS can further improve the precision of velocity and attitude measurements, the RMS of velocity error improvement has reached to 18.2％, 33.3％, 33.3％, the RMS of attitude error improvement has reached to 41.1％, 26.7％, 59.0％.

Research on pseudorange difference method based on virtual observations

ZHAO Yazhi, GU Shouzhou, MI Jinzhong, LIU Yi, CHEN Chong

2019, 44(5): 35-40. doi: DOI:10.13442/j.gnss.1008-9268.2019.05.005

[Abstract](275) [PDF 768KB](58)

Abstract:
Aiming at the problem that the coordinates of the base station of double-difference mode of pseudo-range differential service observation cannot be transmitted on-line and the standard format of pseudo-range correction mode can not be compatible with BeiDou, based on the data of local area CORS network, this paper generates the comprehensive pseudo-range correction number of virtual grid, and further generates the virtual pseudo-range observation value, which can broadcast the pseudo-range to users in real time. Quasi-observed values and station coordinates are used for user differential positioning. Experiments show that virtual grid pseudo-distance difference can provide users with planar submeter-level and vertical positioning services superior to 1.5 m. By analyzing the experimental data, the optimal configuration scheme of grid difference is given. On the basis of solving the above two problems, this method solves the problem of a large number of concurrent users accessing the service algorithmally due to the constant calculation pressure of the server and no limitation of the number of users.

Precision analysis of atmospheric precipitation inversion based on super fast ephemeris

SHI Yun, WU Kangkang, SHEN Jingyu

2019, 44(5): 41-46. doi: DOI:10.13442/j.gnss.1008-9268.2019.05.006

[Abstract](422) [PDF 656KB](108)

Abstract:
Water vapor is an important parameter for weather forecast weather, so it is important to obtain high resolution water vapor products in time. Aiming at the slow update speed and long delay of final precise ephemeris, which can't meet the requirement of real-time retrieving atmospheric precipitable water, a method of retrieving atmospheric precipitable water by using ultra-fast ephemeris instead of final precise ephemeris is proposed. Based on the principle of ground-based GNSS inversion of atmospheric precipitable water, using GAMIT software, the atmospheric precipitable water is obtained according to the ephemeris products with different precision provided by the international GNSS service (IGS) website, and compared with the atmospheric precipitable water obtained by meteorological sounding station. The results show that the atmospheric water obtained from the super fast ephemeris can be consistent with the final precise ephemeris. The average difference is smaller than 0.1 mm, and is consistent with the atmospheric precipitable water measured by the sounding station. The accuracy of the two ephemeris can meet the needs of weather forecasting.

Analysis of influence of CME on noise model and velocity estimation of IGS base station coordinate sequence

MA Feihu, YUE Xiangnan, HE Xiaoxing, JIN Yichen

2019, 44(5): 47-54. doi: DOI:10.13442/j.gnss.1008-9268.2019.05.007

[Abstract](423) [PDF 879KB](92)

Abstract:
In this paper, the coordinate time series of 50 IGS base stations are taken as the research object. The BIC model estimation criterion is used to estimate and analyze the four combined noise characteristics. The influence of CME on the IGS base station coordinate time series noise model and station velocity is discussed. The results show that CME can lead to the biased estimation of the noise model of the IGS base station coordinate sequence, and affect the accuracy of the station velocity. When the base station velocity parameter is accurately estimated, the CME should be corrected. After the CME correction, the annual motion of the IGS base station has an amplitude. The decrease is more obvious in the elevation direction, indicating that the filtered IGS base station annual motion is relatively stable.

A FDR caculation method for GNSS interference analysis

HE Feiyang, LIU Donghua

2019, 44(5): 55-58. doi: DOI:10.13442/j.gnss.1008-9268.2019.05.008

[Abstract](416) [PDF 406KB](83)

Abstract:
In view of the characteristics of frequency-dependent rejection (FDR) calculation in the field of electromagnetic compatibility analysis, such as partial theoremization, insufficient computational accuracy and operability, a FDR calculation method based on Gauss-Lesson integral algorithm and its related software is introduced. Compared with the commonly used calculation methods, the software has the characteristics of high calculation accuracy, simple operation and strong practicability. The typical case studies are used to illustrate the method, which can provide effective support for radio managers in the interference analysis of Global Satellite Navigation System (GNSS).

Analysis of GPS coordinate time series based on the colored noise of ETS

WANG Ziyu, LI Zhongqin

2019, 44(5): 59-65. doi: DOI:10.13442/j.gnss.1008-9268.2019.05.009

[Abstract](370) [PDF 703KB](72)

Abstract:
The 12-year coordinate sequence of 12 GPS stations is studied. The estimation criterion of KIC noise model is used to estimate the four combined noise characteristics, and the influence of slow slip phenomenon on GPS station coordinate time series is discussed. The results show that ETS causes the change of GPS station coordinate sequence model, and the ratios of E, N direction component noise model and U component model are quite different, which may cause erroneous estimation of noise model; the speed of the station and its uncertainty after slow slip are larger than before slow slip; and obvious for the U component. The station at special geographical location can carry out the marking research to minimize the adverse effects caused by the earthquake movement, and study the crustal movement, whih can provide valuable reference materials.

Influences of different interpolation methods on GPS time series

YANG Dengke

2019, 44(5): 66-69. doi: DOI:10.13442/j.gnss.1008-9268.2019.05.010

[Abstract](415) [PDF 436KB](102)

Abstract:
According to the fact that there is no enough research of the comparison of different interpolation methods in the study of time series, this paper chooses seven IGS reference station coordinate time series under the ITRF2008 framework. According to the absence of GPS time series, there are six schemes, which are linear interpolation, cubic spline interpolation, Lagrange interpolation and modeling interpolation. The interpolation effects of different methods are compared and analyzed. The results show that the interpolation effects of cubic spline interpolation and Lagrangian interpolation is poor; when the number of missing value is small, the effects of the nearest neighbour interpolation, linear interpolation, cubic polynomial interpolation and modelling interpolation are similar; with the increase of the number of missing values, the modelling interpolation is the best.

Optimization of GNSS data processing methods in Yunnan and surrounding areas

XU Liangye, SHAO Desheng, WU Xuequn, WANG Lingli, WANG Yan, ZHANG Quilin

2019, 44(5): 70-76. doi: DOI:10.13442/j.gnss.1008-9268.2019.05.011

[Abstract](246) [PDF 715KB](106)

Abstract:
The observation data of 347 global IGS stations from 2015 to 2016 are divided into seven subnets for calculation,with using GAMIT／GLOBK software developed by the Massachusetts institute of technology, and a fixed frame of reference is obtained to calculate the coordinates of 35 GNSS reference stations of Yunnan and surrounding areas.The horizontal direction and vertical direction of the RMS of the measuring station are within 0.7 mm and 0.3 mm,The horizontal coordinate repeatability accuracy is within 5 mm, while the vertical coordinate repeatability accuracy is mostly within 2.5 cm,The comparison with the measured station coordinates, baseline length and horizontal velocity field calculated under ITRF2014 shows that there is systematic error in the station coordinates, the difference in the horizontal direction is less than 8.5 mm, and the difference in the vertical direction is less than 3 cm,the baseline length difference is within 2 mm, and the horizontal velocity field has a difference of millimeter in value, and the direction is basically the same.

Accuracy analysis of single system pseudo range single point location in different areas

XU Ninghui, LU Jie, LIANG Yueji

2019, 44(5): 77-84. doi: DOI:10.13442/j.gnss.1008-9268.2019.05.012

[Abstract](332) [PDF 724KB](148)

Abstract:
In order to explore the accuracy of pseudo-point single-point positioning in different systems in different regions, four singlesystem pseudorange singlepoint positioning models are established in this paper, and the positioning results of each single system are compared and analyzed. The GNSS data provided by MGEX is selected as a case study. The results show that each single system reflects different positioning effects in different regions. In the three directions of N, E and U, the positioning residuals of GPS mostly change between-5 and 5 m; the positioning residuals of GLONASS vary from-15 to 15 m. The positioning results of BDS in the Asian region are far superior to other regions, and the residual changes are more gradual. GALILEO is limited by the length of the period. For longer effective periods, the positioning results and GALILEO in three directions are stable, and the positioning accuracy can reach 5 m.

A study on performance of ionospheric grid information of BDS

LIU Chen, WANG Wei, JIAGN Yi, XU Ao, ZHU Weigang

2019, 44(5): 85-90. doi: DOI:10.13442/j.gnss.1008-9268.2019.05.013

[Abstract](287) [PDF 728KB](105)

Abstract:
Ionospheric delay is one of the main error sources in satellite navigation system, whose correction accuracy directly affects the users’ positioning accuracy. With the BDS navigation satellite system (BDS) fully serving the Asia-Pacific region,there is an increasingly urgent need for BDS to provide users with highprecision positioning and navigation services. At same time, BDS integrates the basic navigation service and Wide Area Difference Service (WADS), releases ionospheric grid information with high update frequency , which can effectively improve the positioning performance. This paper evaluates the service range and service performance of ionospheric grid information service of BDS using data from January 2017 to October 2018. The results indicate that the effective coverage area of ionospheric grid information basically covers China, with a correction deviation of 1.62 TECU and a correction rate of 86.7%. The correction accuracy of ionospheric grid information is lower and more fluctuating in winter with a correction rate of 82%, but higer 87% in other seasons. Both the correction deviation and correction rate are higer during the day than at night. In addition, ionospheric grid information shows strong ability to resist disturbance.

Performance analysis of water vapor detection based on BeiDou precise ephemeris products

WU Xuxiang, GUO Qiuying, HOU Jianhui

2019, 44(5): 91-99. doi: DOI:10.13442/j.gnss.1008-9268.2019.05.014

[Abstract](254) [PDF 963KB](91)

Abstract:
Reserch on the performance of BeiDou satellite navigation system in retrieving atmospheric precipitable water is conducive to promoting the application of BeiDou in numerical weather forecasting and meteorology research. Based on BeiDou final precise ephemeris (WUM) products, rapid ephemeris products (WHR) and ultra rapid ephemeris (WHU) products released by Wuhan University, Using GNSS multimode observation data provided by MGEX station and single CORS station, after verifying that the accuracy of tropospheric zenith delay calculated by the three BeiDou precise ephemeris products meets the requirements, the atmospheric precipitable water vapor calculated by the three BeiDou precise ephemeris products is compared with GPS water vapor detection results, ERA-5 reanalysis data and sounding station data respectively, and the BeiDou water vapor detection performance based on the three precise ephemeris products is analyzed.The experimental results show that the precision of atmospheric water vapor detection based on BeiDou final precise ephemeris products is higher than that of fast ephemeris products and ultra rapid ephemeris products, and the relative accuracy and reliability of atmospheric precipitation inversion of the three kinds of BeiDou ephemeris products are equivalent to that of GPS, which meets the requirements of small and medium scale numerical weather forecasting and meteorology research.

3D modeling method for real scene of buildings based on UAV image

YAO Yongxiang, DUAN Ping, LI Jia, CHENG Libo, LI Chen, WANG Yunchuan

2019, 44(5): 100-105. doi: DOI:10.13442/j.gnss.1008-9268.2019.05.015

[Abstract](368) [PDF 792KB](113)

Abstract:
This paper describes the current development status of three-dimensional (3D) modeling of buildings, and discusses a method of constructing 3D modeling of real-scene buildings by combining an unmanned aerial vehicle oblique image and orientation system (POS) data. The quality and effect of real-scene 3D model modeling are guaranteed by POS aided aerial triangulation, digital surface model construction, real-scene 3D model generation and refined correction of 3D model. The test results show that the constructed real-scene 3D model has high precision, clear texture and small geometric deformation.

Application of GNSS precision control network in super large bridge construction monitoring: a case of the second Humen bridge

WANG Xiaoming, ZENG Xuping, MA Xincheng, YANG Hong

2019, 44(5): 106-110. doi: DOI:10.13442/j.gnss.1008-9268.2019.05.016

[Abstract](357) [PDF 578KB](101)

Abstract:
Taking the second Humen bridge as an example, this paper introduces the specific application of GNSS precision positioning technology in extra large bridges. When calculating baseline, the precision of the control network is improved by improving the precision of the approximate coordinates, choosing the appropriate solution strategy and reasonable constraints, so that the accuracy of the control network results can be improved, and the indicators meet the requirements. The measurement accuracy of the control network is further validated by the statistics of the survey results of Phase 8 of Humen Second Bridge. By calculating the poor coordinates of some points, the specific changes of the points are counted. The stability of the control points is evaluated by the single point test method, which provides a reference for other similar crosssea engineering control networks.

Research on application of GPS elevation fitting in existing orbital elevation survey

REN Jie, HAN Feng

2019, 44(5): 111-116. doi: DOI:10.13442/j.gnss.1008-9268.2019.05.017

[Abstract](284) [PDF 691KB](93)

Abstract:
The application real time kinematic technology is significant for improving the efficiency of the existing track survey. At present, in view of the low efficiency of traditional leveling and the fact that GPS-RTK can not replace traditional leveling methods due to elevation error,a method of plane fitting and quadric surface fitting is proposed to study the accuracy of elevation fitting under different interval control points. Therefore, the real-time kinematic (RTK) and leveling elevation data of inner and outer rails in the same position series are obtained at the test site, and the feasibility and processing method of GPS elevation measurement data based on RTK are analyzed. The results show that,under the condition of introducing a certain control point, the GPS elevation data obtained by using quadric surface fitting can meet the requirements of the existing cable survey within the 500 m interval.

CORS positioning data processing method based on virtual observation and its application

TAI He

2019, 44(5): 117-122. doi: DOI:10.13442/j.gnss.1008-9268.2019.05.018

[Abstract](413) [PDF 634KB](113)

Abstract:
In view of the fact that network RTK under CORS system can not obtain fixed solution in special environment, a post-processing solution method based on virtual observation data is proposed. The process and steps of generating virtual observation data based on Trimble Pivot platform software and calculating the position of observation points by TBC software network are discussed, and the process and steps of calculating the position of observation points by TBC software network are analyzed. The result of SYCORS example analysis shows that the quality evaluation indexes of virtual observation data are equivalent to the real observation data, and the virtual observation data is verified by practical engineering, which confirms that the virtual observation data has certain reliability.