GNSS World of China

Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
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A GNSS control network configuration selection method considering geometric precision factor
GU Jiachen, TIAN Kunjun, SONG Chuanfeng
 doi: 10.12265/j.gnss.2021051401
[Abstract](8) [FullText HTML](1) [PDF 11968KB](1)
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In the relative positioning baseline calculation process, selection of the coordinate position of the control network constraint point has a certain impact on the data calculation accuracy. This paper discusses the site selection method of the control network configuration considering the minimumgeometric factor of precision (GDOP), the selection of 6 constraint point reference stations for the global MGEX (Multi-GNSS Experiment) stations, and the use of BeiDou-2/BeiDou-3 (BDS-2/BDS-3) actual measurement data to compare the results of 18 interactive generator of multimedia application system (iGMAS) stations around the world. The station coordinates are calculated and compared with the accuracy of the results of the global grid-based random station selection method. The experimental results show that compared with the grid-based random station selection method, when the GDOP value selection method is used to calculate the relative positioning baseline, the standard deviation of the baseline length above 6 000 km can be increased by about 7 mm. For the long baseline, the standard deviation accuracy in east (E), north (N), up (U) can be increased by about 5 mm; the position accuracy of the pending point can be increased by about 40%. It can be seen that GDOP method can improve the relative positioning accuracy of BDS-2/BDS-3.
Research and application of encryption conversion parameters in urban CORS system
ZHANG Wei, WANG Lin
 doi: 10.12265/j.gnss.2021123101
[Abstract](9) [FullText HTML](0) [PDF 2131KB](1)
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Aiming at the strict confidentiality of coordinate transformation parameters and quasi geoid model results in urban satellite navigation and positioning continuous operation reference station (CORS) system, a general real-time encryption transformation method of urban CORS system is proposed based on bursa seven parameters and bilinear interpolation method, which realizes the real-time acquisition of plane and normal height results of urban local coordinate system This method has been verified in the application of CORS in Hefei city, and can provide reference for the application service of urban CORS surveying and mapping benchmark.
Positioning principle and engineering application practice of Inertial Navigation System RTK technology
ZHANG Xiangping, YANG Mingguang
 doi: 10.12265/j.gnss.2021121601
[Abstract](6) [FullText HTML](2) [PDF 1934KB](2)
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When using the traditional real-time dynamic positioning (RTK) technology, one must keep the antenna phase center of the Global Navigation Satellite System (GNSS) receiver relatively perpendicular to the measurement point during the measurement to ensure the accuracy of the measurement results. Generally a tripod should be erected. When using the centering rod for measurement, the surveyor must ensure that the leveling bubble of the centering rod call is relatively centered in order to ensure the accuracy of the measurement results. The measurement process is time-consuming and laborious. The emergence of Inertial Navigation System (INS) technology has changed the traditional habit of RTK Surveying and mapping technology. In the measurement process, there is generally no need to erect a tripod, and the measuring centering rod maintain an arbitrary tilt state within a certain range. The measurement process is relatively easy and free, which greatly reduces the labor intensity of measurement and improves the efficiency of surveying and mapping. This paper mainly analyzes the positioning principle and technical advantages of INS technology, and emphasizes that only by mastering the precautions of INS RTK technology in practical application, can it give full play to its maximum benefit and efficiency.
Positioning precision analysis on 5G mm wave and sub-6G signals
QUAN Yiming, CHEN Shian, LIU Guangyin, TANG Xu
 doi: 10.12265/j.gnss.2021120604
[Abstract](6) [FullText HTML](0) [PDF 2399KB](2)
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With the persistent research and rapid commercialization of 5th generation mobile communication technology (5G), China has built one of the largest commercial 5G network. Suppliers of 5G equipment start to provide new positioning features based on 5G new radio (NR). It is highly probable that the high-precision positioning technology will be gradually commercialized in the next few years. Compared with 4G long term evolution (LTE), denser network deployments and wider transmission bandwidth of 5G can bring about a significant improvement in positioning accuracy. Hopefully, 5G positioning can mitigate coverage and accuracy problems of Global Navigation Satellite Systems (GNSS) in difficult environments such as indoor and urban canyons. This article describes the differences between 5G and 4G in the measurement domain. Then the precision of Sub-6G (FR1) and high frequency mm wave (FR2) ranging measurements with Cramér-Rao bound is assessed. Followed by the description of positioning algorithms, eleven scenarios are listed with typical simulation parameters based on 3GPP specifications and commercial network configurations. The simulation results show that the precision of network synchronization is the main factor affecting the positioning quality. If the time synchronization error is 50 ns, 5G positioning precision is over 10 m. A larger bandwidth can significantly improve the ranging precision of 5G signals if the time synchronization problem can be solved by ideal synchronization or double-differencing with positioning nodes near a user end. Under ideal conditions, 5G FR1 can achieve an accuracy of about 1 m, and FR2 can achieve an accuracy of 0.16 m.
Research on normal height service method of grid CORS
ZENG Xiangqiang, CHEN Chunhua, ZHOU Fengsong
 doi: 10.12265/j.gnss.2021121401
[Abstract](99) [FullText HTML](0) [PDF 3005KB](1)
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In this paper, a method of continuously operating reference station (CORS) normal height service based on grid is proposed. By modifying the data generation and broadcast mode of the traditional virtual reference station technology, the grid virtual observation data is generated through the way of grid division, and the elevation anomaly correction is added to the grid virtual observation data, so as to realize real-time normal height measurement. The method provides users with real-time normal height measurement results without reducing their accuracy, which can enhance the service capability of the CORS system and can provide reference for the construction of CORS systems in other provinces and municipalities.
Study on FY-4A PWV correction model in Beijing-Tianjin-Hebei region
WANG Yong, JIANG Nuohan, LIU Yanping, LIU Xiao, ZHAN Wei
 doi: 10.12265/j.gnss.2021092604
[Abstract](3) [FullText HTML](2) [PDF 2421KB](2)
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Integrating Global Navigation Satellite System (GNSS) and Fengyun meteorological satellite FY-4A can obtain high-precision and high-spatial resolution water vapor distribution information. This paper used the GNSS observation data from crustal movement observation network of China (CMONOC) to carry out the FY-4A water vapor correction study in the Beijing-Tianjin-Hebei region. Firstly, the Beijing-Tianjin-Hebei region was divided into four regions, and the correlation analysis between GNSS precipitable water vapor (PWV) and FY-4A PWV was carried out by regions and seasons. Secondly, different function models were selected by region and season and combined with GNSS PWV data to construct the FY-4A PWV correction models. Then, the GNSS PWV was compared with the results of the regional model and the single-site model respectively to carry out the reliability test of the model. Finally, the corrected FY-4A PWV distribution in the Beijing-Tianjin-Hebei region was obtained through regional FY-4A PWV correction and mosaiced. Research shows that the FY-4A PWV has a good correlation with GNSS PWV, and the accuracy of the regional FY-4A PWV correction model is equivalent to that of the single-site model, which can replace the single-site model for the FY-4A PWV correction. The regional model based on CMONOC GNSS PWV can improve the accuracy of FY-4A PWV to a certain extent, and provide references for the short-term weather forecast and InSAR atmospheric correction.
Research on automatic test and evaluation method of GNSS/INS Integrated Navigation Attitude performance based on high-precision three-axis turntable
WANG Jianping, PAN Shuguo, GAO Wang, YU Guorong, HE Liujie, WANG Hao
 doi: 10.12265/j.gnss.2021120901
[Abstract](7) [FullText HTML](3) [PDF 4424KB](0)
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At present, for the Global Navigation Satellite System /Inertial Navigation System (GNSS/INS) performance test and evaluation the evaluation method is single and automatic data processing is still at a low level. Aiming at the attitude performance evaluation of the system, this paper studies a new dynamic test and evaluation method of GNSS/INS performance, and develops corresponding automatic control test and evaluation software. Based on the high-precision three-axis dynamic benchmark simulation turntable, this method first tests through the task of multi rotation and multi attitude motion scene, collects the three-axis motion attitude data of turntable and the output data of integrated navigation system, then processes the measured data by Thompson singular value elimination method, and finally analyzes the uncertainty combined with the measured data of turntable so as to complete the test and evaluation work. In this paper two groups of tests are carried out on a Micro Electro Mechanical System (MEMS) integrated navigation product. Results show that this method can better suppress the singular value points in the integrated navigation system, and the uncertainty values of the turntable are within 0.2", which verifies the high feasibility and reliability of the test and evaluation method.
UAV track planning algorithm in concave polygonal area based on remote sensing mission
LIU Xulin, LI Ronghao, CAI Xiangyuan, CHEN Xiaotong, WEI Jiangnan, LI Qin, ZHAO Hongying
 doi: 10.12265/j.gnss.2022050
[Abstract](12) [FullText HTML](3) [PDF 2746KB](1)
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For the needs and characteristics of remote sensing observing. We proposes an unmanned aerial vehicle (UAV) track planning algorithm based on remote sensing tasks in concave polygonal areas. The algorithm aims to ensure UAV’s non-collision and full area coverage with shorter total time consumption. According to remote sensing image acquisition characteristics, the UAV track planning is carried out by unified main flight direction and fixed-point shooting. The UAV track optimization under the selected main flight direction is obtained through five steps: route segmentation point calculation, polygon division, UAVs assignment, fragment polygon merging and UAVs reassignment, and waypoint information calculation. The global optimal solution is obtained by selecting the main direction of the edges of the concave polygon and its convex hull, respectively. The experimental results show that the algorithm can reasonably assign UAVs and carry out track planning, which is more efficient and more applicable than traditional methods.
Cycle-slip detection and reparation algorithm for satellite-ground two-way time difference measurements
HAN Zibin, BAI Yan, ZHANG Feng, GUO Yanming, LU Xiaochun
 doi: 10.12265/j.gnss.2021120202
[Abstract](4) [FullText HTML](3) [PDF 2873KB](1)
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High precision time-frequency reference requires high precision time-frequency transfer technology. The satellite-ground two-way time difference of carrier phase measurement can achieve higher time-frequency transfer accuracy. However, in the complex satellite-ground environments, due to the high flight dynamics of the spacecraft and the high transmission frequency of the time-frequency link, and the carrier doppler effect is large, gross errors and cycle slips are more likely to occur. This paper focuses on a carrier phase cycle slip detection and reparation algorithm for satellite-ground two-way time difference measurement system in high dynamic environment, and proposes a two-way cycle slip detection and reparation method for three-frequency mode. This method combined with Melbaurne wubbena (MW) combination method can realize the detection and repair of different types of cycle slips. For the three links, the existence of cycle slips can be detected and the mm-level cycle slip repair accuracy can be realized. The satellite-ground time synchronization performance of the satellite-ground two-way time difference measurement system based on carrier phase measurement is further analyzed. After cycle slip detection and repair, and link delay data processing, the time synchronization accuracy is better than 0.3×10–12 s.
ARAIM protection level calculation method for BeiDou decimeter level single epoch point positioning
WEI Yiran, GUO Jiang, FANG Shushan
 doi: 10.12265/j.gnss.2022021
[Abstract](19) [FullText HTML](7) [PDF 3511KB](1)
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Precision positioning quality control and integrity assessment is an integral part of real-time Global Navigation Satellite System (GNSS) navigation applications, especially in GNSS vulnerable urban canyon scenarios. Wide-area precise point positioning (PPP) instantaneous decimeter level positioning can be realized by using the observation values of two wide lanes formed by GNSS three-frequency signal. However, in the complex urban environment, the impact of reflected signals, serious multipath and other signal interference on positioning cannot be accurately evaluated and identified, which limits the application of PPP instantaneous decimeter-level point positioning. advanced receiver autonomous integrity monitoring (ARAIM) in the concept of integrity can calculate the upper limit protection level(PL) of the minimum confidence interval of user positioning error to evaluate the positioning effectiveness, which can be used for quality control of PPP instantaneous positioning after some improvement. Aiming at the problem that the error model used to calculate the PL in ARAIM is difficult to meet the requirements of high-precision positioning, an improved ARAIM PL algorithm which is called B-ARAIM is proposed in this paper. The residual of PPP three-frequency combination observation value is used to modify the ARAIM weight and error model to calculate the PL. This paper verifies the algorithm based on on-board data collected in environments with different complexity levels, and evaluates the improvement of PL and the improvement of navigation availability. The results show that the PL obtained by the improved B-ARAIM algorithm is more in line with the needs of city positioning than that obtained by the traditional method, and the PL is reduced by 30% to 70% in different environments. This method is helpful to the application of ARAIM algorithm in GNSS positioning.
Optimization algorithm of earthquake early warning alarms based on multi-station high frequency GPS
ZHANG Wenhao, YIN Ling, HU Wenbo
 doi: 10.12265/j.gnss.2021120205
[Abstract](3) [FullText HTML](1) [PDF 4174KB](1)
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With the development of precision positioning technology, high-frequency GPS has been able to accurately record surface displacement data. Research on high frequency GPS can make a certain supplement to earthquake early warning. In view of the high false alarm rate of single station in earthquake early warning, we introduce deep learning technology and use the long short-term memory (LSTM) neural network to combine with surrounding stations to give early warning to single station. First, the seismic-free time series of multiple stations are obtained by solving the 1Hz high-frequency GPS data in the southern region of New Zealand Then the data is used to train the network to obtain a high-precision model that integrates regional features. The model can predict the seismic-free time series and dynamically formulate a threshold interval. When the actual observation value exceeds the confidence interval, an abnormality is determined. By comparing with the traditional short-time window averaging/long-time window averaging algorithm (STA/LTA) and the single station model without regional features, the results show that the single station model fusing regional features can effectively reduce false alarms, It performs better than traditional methods on seismic-free long sequences of multiple stations and has certain application values.
Application of Helmert variance component estimation in GPS/GLONASS/BDS/Galileo combined precise point positioning weight determination
LI Qin, YAO Wanqiang, TU Rui
 doi: 10.12265/j.gnss.2022047
[Abstract](12) [FullText HTML](4) [PDF 3391KB](2)
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Multi-constellation combined positioning can improve the performance of navigation and positioning, but a suitable stochastic model needs to be considered when combining observations from different constellations. The traditional method is to directly set the equivalent weight of each system based on experience, which will lead to inaccurate determination of the stochastic model, and thus affect the performance improvement of the combined system. In this paper, Helmert variance component estimation method is applied to GPS/GLONASS/BDS/Galileo combined precise point positioning to adaptively determine the weight ratio between systems. The static and pseudo-dynamic tests were carried out using the daily observation dataset collected at 10 stations in the global International GNSS Service (IGS) Multi-GNSS experiment (MGEX) observation network over one week of February 8 to February 14, 2021. The results show that the Helmert variance component estimation weighting method can significantly improve the convergence speed of GPS/GLONASS/BDS/Galileo combined precise point positioning (PPP), with an average increase of 52 % in static mode and 64 % in pseudo-dynamic mode. Because the positioning accuracy is mainly determined by the carrier phase observation accuracy and error correction level, the Helmert variance component estimation method has no obvious improvement on positioning accuracy in static and pseudo-dynamic tests.
Method for eliminating pseudolite near-far effect based on orthogonal subspace projection
SHI Shang, WANG Qing, ZHANG Bo, YANG Yuan, XU Jiujing
 doi: 10.12265/j.gnss.2021111701
[Abstract](10) [FullText HTML](0) [PDF 3878KB](1)
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Receivers in ground-based pseudolite systems are often affected by the near-far effect, causing failure acquisition of far-field pseudolite signals. An optimization method based on orthogonal subspace projection is introduced in this paper, which is applied to code division multiple access(CDMA) pseudolite signals. Firstly, strong-signal code phases and Doppler frequencies are obtained through conventional sliding correlation to calculate the orthogonal projection operator. Then the weak-signal space is obtained by the received signal subtracting its projection in the strong-signal space. Finally, the re-acquisition is done in the weak-signal space to eliminate of the interference of strong signals. The experimental result indicates that the orthogonal subspace projection can effectively improve weak-signal acquisition performance in the power ratio range of lower than 30 dB, which is of great importance to widen the effective working range of ground-based pseudolite systems and the limitation of pseudolite receivers’ signal power ratio tolerance.
Research on data processing method of BDS assisted unmanned aerial vehicle image-free control triangulation
FAN Yanwei, MA Cheng
 doi: 10.12265/j.gnss.2021122101
[Abstract](2) [FullText HTML](0) [PDF 2702KB](1)
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Aiming at the problem of large number of field control points and heavy workload in the spatial triangular processing of unmanned aerial vehicle , the BeiDou Navigation Satellite System (BDS) assisted unmanned aerial vehicle large-scale image control free accuracy verification method is proposed in this paper. The unmanned aerial vehicle photogrammetry platform equipped with dual frequency Global Navigation Satellite System (GNSS) receiver is used to receive BDS data. The key technologies of high-precision BDS camera station coordinate solution and joint adjustment of BDS data and unmanned aerial vehicle image data are discussed and analyzed. Finally, an engineering example is given to verify the effectiveness of the method. The experimental results show that the method can meet the accuracy requirements of 1∶500 large scale mapping without the participation of image control points.
Analysis of common mode error of GNSS coordinate time series in Xinjiang with independent component analysis
LEI Chuanjin, WEI Guanjun, GAO Maoning, ZHANG Pei
 doi: 10.12265/j.gnss.2021111201
[Abstract](7) [FullText HTML](1) [PDF 7445KB](3)
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The common mode error (CME) is one of the major error sources in the regional Global Navigation Satellite System (GNSS) network. Aiming at the problem that GNSS time series is subject to no-Gaussian distribution, and the principal component analysis (PCA) with second-order is inaccurately employed to separate the CME. In this paper, the independent component analysis (ICA) introduces high-order statistics to extract the common mode error (CME). The effectiveness of the method is validated by processing the data of GNSS stations from 2011 to 2018 in Xinjiang, China, and then compared and verified the filtering effect of PCA. We analysis the influence of the CME for GNSS coordinate time series and the yearly signal of the CME. The results show that the CME mainly consists of the 6th independent components and can be attributed to satellite orbit, surface mass loading, and clock errors. After the ICA filtering, the reduction of mean RMS is 31.83%,32.29%,35.49% for the north, east, and up components, respectively. The reduction of velocity uncertainty can achieve 44.14%,38.49%, and 35.49% in three components. In addition, the yearly amplitude of each GNSS station is more consistent that before spatiotemporal filtering, indicating that the ICA can effectively extract the CME and further improve the accuracy of coordinate time series.
Comparative analysis of three GNSS data download methods
WU Tangting, LIANG Qiao, CHEN Baogui, LU Liguo
 doi: 10.12265/j.gnss.2021120602
[Abstract](8) [FullText HTML](6) [PDF 3287KB](7)
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In order to comprehensively evaluate the performance of single-thread, multi-thread, and multi-coroutine in Global Navigation Satellite System (GNSS) data download, this paper uses the International GNSS Service (IGS) data center of Wuhan University as the download source and analyzes the download effects of three methods in terms of the time span and magnitude of the download file. The results show that in the process of small and medium-sized files download, multi-thread has more advantages than single-thread and multi-coroutine,while for large file downloads, the download effect of multi-coroutine is slightly better than multi-thread, and both have better performance than that of single-thread. Since GNSS data file is generally small and medium-sized file, multi-thread is more suitable for GNSS data download.
Design and verification of semi-physical simulation platform for LEO satellite navigation enhancement system
LIU Tianli, YANG Xuan, LIU Xiaoxu
 doi: 10.12265/j.gnss.2021112601
[Abstract](5) [FullText HTML](0) [PDF 2417KB](1)
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Low earth orbit (LEO) satellite has the advantages of rapid change of geometric configuration relative to the ground and low loss of broadcast signal link. With the gradual reduction of low orbit satellite load development and launch cost, low orbit satellite navigation enhancement technology has become a research hotspot in the field of satellite navigation. At present, the research on LEO navigation enhancement technology at home and abroad is in its infancy. There is no mature LEO navigation satellite constellation, and there is no effective means to verify the service performance of LEO navigation enhancement system. In this paper, the orbit extrapolation method of LEO navigation satellite and the signal acquisition and tracking technology of LEO satellite are studied, and the semi-physical simulation platform of LEO navigation enhancement system is designed and constructed. On the basis of the simulation platform, the high-precision fast precision positioning method of the combined application of BeiDou system / LEO enhancement system is verified, which realizes the rapid convergence of precision single point positioning (PPP) and has high internal coincidence accuracy. It has certain scientific and engineering value for the construction and application of LEO satellite navigation enhancement system.
An efficient demodulation algorithm for CSK modulated signals based on partial output FFT
LI Ye, ZHOU Guodong, XIAO Linwei, CHEN Huaming
 doi: 10.12265/j.gnss.2022019
[Abstract](12) [FullText HTML](4) [PDF 2422KB](1)
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In order to broadcast precise ephemeris data with high speed, code shift keying (CSK) modulation is likely to be adopted in next generation satellite navigation system. The correlation values of various code phase offsets are needed during demodulation, so the frequency domain demodulation algorithm based on fast Fourier transform (FFT) is usually used. According to the characteristic that only partial output are needed in CSK frequency domain demodulation, an efficient demodulation algorithm for CSK signal based on partial output FFT is proposed in this paper. The algorithm optimizes the butterfly-shaped structure of traditional FFT, and reduces the computational complexity of demodulation by defining computing nodes to eliminate invalid computations irrelevant to the output results. Taking the CSK(4,1023) modulated signal with a code rate of 1.023 Mcps as an example, the algorithm proposed in this paper can reduce about 45.6% of the calculation, which is of great significance to the design of the next generation satellite navigation receiver.
Design and implementation of navigation synthetical baseband equipment
ZHANG Jintao, HAN Shuanglin, YANG Liyun, HU Zhengqun
 doi: 10.12265/j.gnss.2021092603
[Abstract](21) [FullText HTML](1) [PDF 3326KB](60)
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Chinese area positioning system (CAPS) is a new satellite navigation system with independent intellectual property rights in China. Based on the working mode of the satellite forwarding the navigation signal generated on the ground, the satellite navigation function is realized. Navigation integrated baseband is an important terminal equipment of the main control station of CAPS. The architecture of navigation integrated baseband is designed by software radio design. Standard PCI extensions for instrumentation (PXI) chassis structure and bus-based design with strong scalability is selected. The key technologies of baseband are described including frequency compensation technology of transmitting signals, high precision receiving technology, high stability delay keeping technology of equipment. The actual test results show the good performance of the integrated baseband equipment. The measurement accuracy of pseudorange is better than 0.20 ns. The stability of channel delay is better than 0.25 ns, and the accuracy of frequency compensation is better than 0.8 Hz, which can meet the needs of CAPS.
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2022, 47(2).  
[Abstract](83) [FullText HTML](44) [PDF 1921KB](95)
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2022, 47(2): 1-2.  
[Abstract](79) [FullText HTML](40) [PDF 6189KB](97)
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Inversion of shipborne meteorological sensor height above water surface based on GNSS carrier-to-noise ratio
QIU Zhijin, HU Tong, ZOU Jing, LI Zhiqian, WANG Bo
2022, 47(2): 1-6.   doi: 10.12265/j.gnss.2021101301
[Abstract](46) [FullText HTML](6) [PDF 2810KB](73)
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The height of shipborne meteorological sensor above water surface is a necessary parameter to predict the atmospheric refractive index profile by using the bulk aerodynamical method, which is of great significance to the radio meteorological parameter monitoring systems such as evaporation duct monitoring system. The Global Navigation Satellite System (GNSS) carrier-to-noise ratio (CNR) is extracted from the shipborne GNSS receiver output. The coherence of GNSS direct signal and reflected signal from water surface is analyzed using Lomb Scargle Periodogram to retrieve the height of the GNSS antenna phase center above reflection surface, and then the height of shipborne meteorological sensor is calculated indirectly. The proposed method was verified by barge experiments. Based on the statistics of the effective inversions, the sea state influence on the inversion results as well as the time-averaged variation of the inversion results is analyzed. It shows that the height of shipborne meteorological sensor can be effectively retrieved.
Analysis of GNSS landslide geological hazard monitoring data processing strategy based on CORS reference station
LIU Xingwei, CAI Hua, PU Dexiang, WANG Bin
2022, 47(2): 7-12.   doi: 10.12265/j.gnss.2021101302
[Abstract](64) [FullText HTML](8) [PDF 2075KB](79)
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In order to give full play to the resource advantages of continuously operating reference stations (CORS) in the field of landslide geological hazard monitoring, the deformation monitoring data processing strategy based on CORS reference station is analyzed, the effects of observation value type, calculation time and baseline length on monitoring accuracy are evaluated, and the coverage of CORS reference station as monitoring reference is given, It provides important data support for promoting the in-depth application of CORS in deformation monitoring.
Multi-GNSS clock combination with satellite attitude correction
MAO Shuyin, WEI Na, WEN Qiang, YAN Zhe
2022, 47(2): 13-20.   doi: 10.12265/j.gnss.2021111801
[Abstract](57) [FullText HTML](6) [PDF 2906KB](11)
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International GNSS Service (IGS) has been continuously providing high-precision combined GPS orbit and clock products, which is widely used in various scientific research and operational applications. However, with the prosperity of Global Navigation Satellite System (GNSS), combination strategies of multi-GNSS (GPS, GLONASS, Galileo and BDS) products is now urgently needed. Besides, due to the coupling relationship between satellite attitudes and clocks, the clock consistency during combination can be further improved by considering attitude differences. Therefore, we proposed a multi-GNSS clock combination strategy considering attitude correction. It is found that GPS clock combination residuals can be reduced by 80% at most after applying attitude correction. Additionally, we conducted static and kinematic positioning for 142 globally distributed stations using the combined products. Compared to the products provided by a single analysis center, the GPS/GLONASS/Galileo combined products are more stable and can improve the positioning quality up to 22.7%, 16.7% and 18.3% for the three components during kinematic positioning. Adding attitude corrections during clock combination can improve the kinematic positioning accuracy up to 65.3% at a single station.
Application of moving horizon estimation method for altitude constrained pseudo-range single-point positioning
SUN Shuguang, YANG Xiangyuan, CHEN Wantong, ZHANG Julian, LIU Qing, REN Shiyu
2022, 47(2): 21-26, 89.   doi: 10.12265/j.gnss.2021092601
[Abstract](36) [FullText HTML](2) [PDF 2802KB](13)
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In order to improve the positioning performance of pseudo-range single-point positioning (SPP) technology in Global Navigation Satellite System (GNSS), a moving horizon estimation (MHE) algorithm with height constraint was proposed. On the basis of adding height as nonlinear constraint to SPP parameter estimation, constrained MHE algorithm is used to improve the accuracy of SPP. Experiments show that compared with the least squares (LS) method, the MHE filter based on high constraint has better smoothing performance, and the effectiveness and feasibility of MHE scheme with additional height constraints are verified. The results obtained are of great significance to the practical application of SPP.
Practice and discussion on integration transformation of satellite positioning continuous operation reference station network in Hefei
ZHANG Wei, WANG Lin
2022, 47(2): 27-31.   doi: 10.12265/j.gnss.2021112402
[Abstract](65) [FullText HTML](6) [PDF 3323KB](12)
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Aiming at the problem that three sets of continuously operating reference stations (CORS) systems in Hefei operate independently and the benchmark framework and service standards are not unified, A unified satellite positioning continuous operation benchmark station network in Hefei is established in order to serve natural resources and planning better. This paper discusses the deep integration construction of reference station, the upgrading of system software and hardware, the compatibility with existing software and hardware, networking design, and the practice of CORS benchmark framework coordinate joint measurement and expansion service. A variety of shared integration technologies are comprehensively used to verify the correctness and feasibility of the method through field measurement, which has a good reference significance for the integration transformation of urban CORS.
Inversion of groundwater reserves changes in Queensland by GRACE
NAI Jin, WEI Changshou, TENG Lei, ZHAO Yueyao
2022, 47(2): 32-37.   doi: 10.12265/j.gnss.2021071602
[Abstract](57) [FullText HTML](7) [PDF 2430KB](13)
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Queensland is the second largest state in Australia. Monitoring and analysis of changes in groundwater reserves in this region this of great practical significance to the formulation of local ecological environment and water management policies, The time-varying gravity field model from gravity recovery and climate experiment (GRACE) issued by the University of texas center for space research (CSR) and the global land data assimilation system (GLDAS) surface assimilation model are used to monitor and analyze the temporal and spatial changes of groundwater reserves in Queensland, which are then verifled and analyzed with measured well data and global precipitation climatology project (GPCP) rainfall data. The research results show that the groundwater increassd at a rate of 1.3±0.09 cm/a in Queensland was approximately in 2003 to 2015. There is also a significant spatial difference between the east and the west. The comparison with the GPCP rainfall data shows that the rainfall is the main factor affecting the change of groundwater reserves, The comparison with the measured data of the water well reveals that the change trend of the underground inversion result is basically consistent with that of the water level of the well.
Application of sliding generalized extension interpolation method in GLONASS precise clock correction
HUA Xirui
2022, 47(2): 38-43.   doi: 10.12265/j.gnss.2021101308
[Abstract](21) [FullText HTML](3) [PDF 2137KB](4)
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In the interpolation of satellite clock data, the accuracy of interpolation algorithm directly affects the accuracy of satellite clock interpolation results, which affects the accuracy of satellite navigation and positioning. Therefore, an appropriate interpolation method should be selected when interpolating satellite clock data. In this paper, the Lagrange interpolation method and Chebyshev fitting method are used for sliding, these two traditional interpolation methods and sliding generalized extension interpolation method are used to interpolate the GLONASS clock error data with an epoch interval of 5 min into 30 s. Results are compared with the precision clock error data of 30 s. The application effect of the three interpolation methods in GLONASS satellite clock error data is analyzed. The obtained results show that the interpolation accuracy of these three interpolation methods can meet the requirements of GLONASS satellite clock data interpolation, and the sliding generalized extension interpolation method has the highest interpolation accuracy.
Research on orbit fitting and forecasting accuracy of different orbit types’ LEO satellites
TAN Liqing, PENG Qi, CAO Yang, YANG Xin, TANG Shuai, LIU Jun
2022, 47(2): 44-51.   doi: 10.12265/j.gnss.2021083101
[Abstract](25) [FullText HTML](5) [PDF 6929KB](6)
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The accuracy of low earth orbit (LEO) satellite orbits directly affects the application areas of LEO satellites, so it’s very meaningful and necessary work so as to study appropriate models to improve the fitting/forecasting accuracy of LEO satellite orbit. The fitting/forecasting accuracy of sliding Chebyshev polynomial and Kriging algorithm in different types of LEO orbits were studied in this paper, the results show that: both algorithms can obtain millimeter-level interpolation accuracy with a suitable fitting strategy. Compared to the sliding Chebyshev fitting algorithm, the spatial error distribution of the kriging algorithm fitting orbit is more concentrated, and it does not fluctuate sharply with the change of epoch. The prediction accuracy of the Kriging algorithm is lower than the sliding Chebyshev polynomial. When the Kriging algorithm is used to forecast 60 seconds, the forecasting accuracy can reach 1 to 2.5 m. While the sliding Chebyshev polynomial’s forecasting accuracy of 120 seconds is better than 5 m in each LEO satellite.
Weighted positioning method based on RSSI probability distribution and Bayesian estimation
NIE Dawei, ZHU Hai, WU Fei, HAN Xuefa
2022, 47(2): 52-59.   doi: 10.12265/j/gnss.2021080902
[Abstract](0) [FullText HTML](0) [PDF 3047KB](7)
Abstract:
Aiming at the problem that the traditional Wi-Fi positioning technology based on distance measurement does not consider the distribution characteristics of received signal strength indication (RSSI) values, which may result in poor indoor positioning results, this paper proposes a weighted positioning method based on RSSI probability distribution and Bayesian estimation. On the basis of studying the stationarity and distribution characteristics of RSSI. The method introduces the prior RSSI probability distribution into to the calculation of weight through Bayesian estimation. It can also give lower weights to outliers go as to reduce the impact of environmental noise and external uncertain factors on the positioning accuracy, then the position with the largest weight will be taken as the positioning result. Experimental results show that compared with results of trilateral localization, weighted centroid localization and weight correction algorithm, the average error of this method is reduced by 45.4%, 14.6%, 8.2%, and the error of cumulative probability within 50% is reduced by 66.7%, 42.1%, 32.4%.
Availability analysis for ionospheric gird model in China areas under multi-GNSS observations
WANG Huafeng, ZHANG Yanru, CAI Hongtao, GUO Shan
2022, 47(2): 60-65.   doi: 10.12265/j.gnss.2021050602
[Abstract](39) [FullText HTML](13) [PDF 4118KB](10)
Abstract:
While multi-Global Navigation Satellite System (GNSS) observation make it possible for a better performance of ionospheric model for Space Based Augmentation System (SBAS), the potential improvement depends on various factors. The paper analyzes the availability of ionospheric grid model for SBAS covering China and around areas under multi-GNSS scenarios. The results show that the covering area of grid model could be extended with multi-GNSS measurements. But for southern China, where equatorial ionolization anomaly (EIA) exists, the performance improves marginally as the increased observations cannot counter effectively the EIA’s serious impacts on grid model. In northern China, the ionosphere varies smoothly and multi-GNSS observations are helpful to reduce the number of sites while maintains the system performance.
The analysis of ground deformation about Qinghai Maduo M7.4 earthquake based on GNSS
LI Kang, JIANG Guangwei, GAO Chunwei, WANG Zushun, GAO Xinyan, DANG Yinqun
2022, 47(2): 66-72.   doi: 10.12265/j.gnss.2021081803
[Abstract](29) [FullText HTML](12) [PDF 3386KB](11)
Abstract:
On May 22, 2021, Beijing time, an M7.4 earthquake occurred in Maduo, Qinghai province, which affected the regional stations. In this paper, we collected high-frequency observation data of Global Navigation Satellite System (GNSS) continuously operating reference stations (CORS) in Qinghai Province , which is less than 400 km from the epicenter. Using International GNSS Service (IGS) stations and China continental tectonic environment monitoring network as reference stations, static and dynamic models were used to analyze the three-dimensional surface deformation after the earthquake. The results show that, the displacement magnitude of the site shows a trend of attenuation as the epicenter distance increases. Among them, the Jiangduo station, which is about 35 km away from the epicenter, produces a permanent displacement of 28.0 cm to the south east. On the whole, the impact of the earthquake on the focal area within 100 km is shown as a strike-slip motion, which is consistent with the focal mechanism. The regional motion characteristics are generally shown as extensional-compression motion, NW-SE extension and NE-SW compression.
Path planning of intelligent aircraft based on linear matrix inequality
SHEN Tiantian, YUAN Simin, WU Fang, CHEN Zhongxiang, YU Guo
2022, 47(2): 73-81.   doi: 10.12265/j.gnss.2021083103
[Abstract](65) [FullText HTML](42) [PDF 2619KB](11)
Abstract:
Intelligent aircraft plays an increasingly important role in a variety of applications. The aircraft's position accuracy while arriving at the application scenery is required. And it necessitates the flight's trajectory planning with appropriate position corrections due to the accumulated position errors that usually occur during the flight. To this end, this paper proposes a trajectory planning method for an intelligent aircraft working in some complex conditions, where an linear matrix inequality (LMI)-based optimizing method is utilized to achieve the dual goal of minimum correction times and minimum travel length. According to the number of available correction points and their different influences on the aircraft position, a triangular variable matrix with 0-1 entries is first designed to represent a flight trajectory that starts from point A, traverses a series of correction points in a target-oriented manner without any repetition, and ultimately arrives at the target point. After that, several other compulsory constranits are imposed on the trajectory-related matrix's variable entries, all of these constranits are later transformed and imposed on the previously defined variable matrix as a whole. The LMI-based optimizing method is performed to achieve the dual goal. Simulational results validate the proposed trajectory planning method and demonstrate its remarkable performance in the sense of less computing resources and optimization results, compared with many other optimization methods such as linear pro-gramming.
Ridge estimation method for linearized general EIV adjustment model
WENG Ye, SHAO Desheng, GAN Shu
2022, 47(2): 82-89.   doi: 10.12265/j.gnss.2021083001
[Abstract](24) [FullText HTML](3) [PDF 2345KB](5)
Abstract:
As a general form of classical adjustment model, general errors-in-variables (EIV) adjustment model has the advantage of taking into account multiple random errors. Based on the linear estimation of the weighted total least squares of the general EIV adjustment model, the regularization criterion is introduced. When the regularization matrix is the unit matrix, it is called the ridge estimation. The objective function is then added. By establishing the minimization solution of the Lagrange objective function, the ridge estimation solution corresponding to the weighted general EIV adjustment model is derived. The U curve method and L curve method for determining ridge parameters are given. The linear estimation, two ridge estimations and their corresponding variance components of the general EIV adjustment model are calculated. It is validated that ridge estimation can promote the linearization estimation of general EIV model, reduce the times of iterations, make the parameter variance component more stable and reduce the calculation of parameter estimation.
Time series nonlinear deformation removal of GNSS coordinates based on ICEEMDAN and environmental load
WANG Yong, CAO Huipeng, LI Suo, YAN Yong, YANG Jun
2022, 47(2): 90-98.   doi: 10.12265/j.gnss.2021092602
[Abstract](43) [FullText HTML](9) [PDF 3812KB](7)
Abstract:
Nonlinear deformation affects Global Navigation Satellite System (GNSS) coordinate timing accuracy. In this paper, improved complete ensemble empirical mode decomposition with adaptive noise (ICEEMDAN) method and environmental load correction are combined to study the nonlinear deformation removal of GNSS stations. Firstly, use GMIS software to complete the GNSS coordinate timing and remove the gross error. Then use ICEEMDAN method to decompose the GNSS coordinate timing, and use the permutation entropy algorithm to select the high frequency components containing noise and nonlinear deformation. Finally, the environmental load is used to remove the high-frequency components, and the removal effect is compared with the empirical mode decomposition (EMD) method and the environmental load method. The research results show that the root mean squared (RMS) of GNSS coordinate time series after nonlinear deformation removal changes different, and the up (U) direction is the most obvious, with the maximum value of 6.715 mm, followed by the E direction and the north (N) direction. After combining ICEEMDAN met-hod and environmental load,the nonlinear deformation in N direction was weakened 75% of the nonlinear deformation in east (E) direction was weakened, and 62.5% of the nonlinear deformation in U direction was weakened. The correction effect was better than the combination of EMD method and environmental load.
Analysis of network RTK precision of grid high precision satellite navigation and positioning service method
WU Haile
2022, 47(2): 99-103.   doi: 10.12265/j.gnss.2021102201
[Abstract](31) [FullText HTML](4) [PDF 2558KB](8)
Abstract:
This paper introduced the grid high precision satellite navigation and positioning service method, which improved the virtual reference station (VRS) method. And analyzed the impact of different virtual grid resolutions to the network real time kinematic (RTK) precision. The performance test was then proceed using the normal grid resolution in the knimatic application to analyze the knimatic network RTK precision. Result shows that the network real time kinematic RTK precision will degrad as the distance increases. The precision of the 2′×2′ and 4′×4′ virtual grid resolutions is nearly the same and both wthin centimeter level, which means that 4′×4′ virtual grid resolution can be as a regular selection, so as to meet the requirements of calculation and positioning accuracy of centimeter level for relatively ficed virtual grid point. In addition, results under the condition of regular grid resolution show that the extent of the horizontal direction residual sequence of the knimatic application is the centimeter level, and the height direction residual sequence is the decimeter level. So that the regular grid resolution can fulfil the requirements of the vehicle dynamic applications.
A BDS-based millimeter-level foundation pit wall displacement monitoring and early warning system
PAN Jundao, CAI Haoyuan, LIU Zhenyao, WU Chunqiu, ZHANG Bangfu, YANG Bin, LIU Fengmin, ZHAO Shenglin
2022, 47(2): 104-109.   doi: 10.12265/j.gnss.2021110801
[Abstract](37) [FullText HTML](7) [PDF 2805KB](13)
Abstract:
Aiming at the potential safety hazards caused by the horizontal displacement and settlement of the building's foundation pit wall and the foundation pit slope during the construction of the building, a monitoring system for the displacement of the foundation pit wall is designed. The BeiDou Navigation Satellite System (BDS) observation data is collected regularly by measuring points and combined on the server. The reference station data sequence is used to process the displacement monitoring data of each monitoring point. Finally, the Shewhart mean value control chart is used. When the displacement of the measuring point exceeds the threshold, the system will give an alarm. The measuring point will give a set of measured values every 60 minutes, which is quasi-static. The test results show that the system can achieve a precision of 5 mm in the east (E) direction; 4 mm in the north (N) direction; and 9 mm in the up (U) direction for monitoring.
BeiDou satellite clock error prediction based on optimal weight combination method
ZHAO Jinxia, ZHANG Xiaoning
2022, 47(2): 110-113, 125.   doi: 10.12265/j.gnss.2021101309
[Abstract](26) [FullText HTML](4) [PDF 2227KB](11)
Abstract:
In view of the lack of research on BeiDou satellite clock error prediction, this paper constructs a new combined prediction model based on grey model and neural network model. The combined clock error prediction model effectively combines the advantages of two single models through the optimal weight method to realize the short-term prediction of Beidou clock error. Finally, Taking the atomic clock data carried by the three types of Beidou satellites as an example, the weight of each single model is calculated, and the short-term prediction of clock error is realized by constructing the optimal weight prediction model. The prediction results are better than the two single models, which proves the effectiveness and applicability of the combined prediction model in the short-term prediction of clock error.
Accuracy assessment of BDS-3 satellite signal-in-space
LIU Dongliang, CHENG Fang, SHEN Pengli, LI Yanhong, LI Xiaowan
2022, 47(2): 114-125.   doi: 10.12265/j.gnss.2021112201
[Abstract](57) [FullText HTML](13) [PDF 8944KB](22)
Abstract:
Aiming at the accuracy of the signal-in-space after BeiDou-3 (BDS-3) is officially opened, The paper selected one-year Global Navigation Satellite System (GNSS) mixed broadcast ephemeris data (from August 1st, 2020 to July 31st, 2021) and used the precision orbit and clock offset provided by the German Potsdam Geoscience Research Center (GFZ) and International Global Navigation Satellite System Service (IGS) data center of Wuhan as reference to evaluate the accuracy of the BDS-3 signal-in-space. The research showed the orbit accuracy of the BDS-3 is better than 0.100 m, 0.405 m, and 0.547 m in the radial, along-track, and cross-track respectively, and the clock error accuracy is better than 1.926 ns, and SISRE statistical accuracy only affected by the orbit error is 0.134 m, and signal-in-space range error (SISRE) statistical accuracy is 0.612 m. SISRE of the geostationary orbit (GEO) satellites is 1.137 m. Compared with the GEO satellites, and SISRE of the inclined geosynchronous orbit (IGSO) satellites and the medium earth orbit (MEO) satellites are reduced by 36.3% and 51.3% respectively.
Research on key technologies of location service based on BeiDou ground based augmentation systems
DU Zhongjin
2022, 47(2): 126-132.   doi: 10.12265/j.gnss.2021101304
[Abstract](35) [FullText HTML](17) [PDF 2447KB](17)
Abstract:
Based on the resources of provincial BeiDou ground based augmentation systems, this paper combines the production needs of natural resources industry, carries out research on key technologies such as “virtual grid technology” and “location service response technology of large-scale concurrent users” based on space-time information technology, and develops the location service platform of Fujian BeiDou ground based augmentation system. It integrates the functions of system operation and maintenance, public service, achievement display and data sharing, improves the level and ability of public service, and meets the demand of large-scale real-time location service.
Analysis on the earth rotation parameters under different means
CHEN Shaojie, GAO Yuping, SHI Chunlin, YIN Dongshan, WANG Qihong, CHEN Yongtao
2022, 47(2): 133-138.   doi: 10.12265/j.gnss.2021101305
[Abstract](24) [FullText HTML](3) [PDF 2472KB](13)
Abstract:
With the use of various space geodetic methods such as very long baseline interferometry (VLBI), satellite laser ranging (SLR), lunar laser ranging (LLR), Global Navigation Satellite System (GNSS), Doppler orbitograph and radio positioning integrated by satellite (DORIS), etc., the measurement accuracy of earth rotation parameters (ERP) has been continuously improved. It provides high-precision conversion parameters between the International Celestial Reference System (ICRS) and the International Terrestrial Reference System (ITRS) for many fields such as spacecraft navigation and deep space exploration.This article mainly uses the C04 sequence published by the International Earth Rotation and Reference System Service as the basic sequence, the 500 days ERP sequence was selected and the error distribution of the ERP data obtained by different measurement methods was analyzed. It provides data basis for studying the feasibility and accuracy level of accuracy checking by using the consistency between different data, and also provides more data options for ERP forecasts.
Construction and development of satellite navigation augmentation systems
GUO Shuren, LIU Cheng, GAO Weiguang, LU Jun
2019, 44(2): 1-12.   doi: DOI:10.13442/j.gnss.1008-9268.2019.02.001
[Abstract](1227) [PDF 1536KB](1114)
摘要:
Accuracy analysis of BDS-2/BDS-3 standard point positioning
FANG Xinqi, FAN Lei
2020, 45(1): 19-25.   doi: DOI:10.13442/j.gnss.1008-9268.2020.01.003
[Abstract](504) [PDF 750KB](132)
摘要:
  Dynamic Positioning Accuracy Test and Analysis of BeiDou Satellite Navigation System
ZHANG Fengzhao, LIU Ruihua, NI Yude, WANG Ying
2018, 43(1): 43-48.   doi: 0.13442/j.gnss.1008-9268.2018.01.008
[Abstract](1121) [PDF 1895KB](251)
摘要:
Overview of Satellite Navigation Spoofing Signal Detection Technology
ZHANG Xin
2018, 43(6): 1-7.   doi: doi:10.13442/j.gnss.1008-9268.2018.06.001
[Abstract](873) [PDF 93258KB](207)
摘要:
A New Method of NMEA0813 Protocol Parsing
LIU Fushan, GUO Chengjun, JIA Zhendong
2017, 42(1): 70-73.   doi: 10.13442/j.gnss.1008-9268.2017.01.014
[Abstract](502) [PDF 476KB](109)
摘要:
High Precision GPS/BDS Data Processing and Precision Contrast Analysis Based on GAMIT10.61
LIU Xingwei, PU Dexiang, GAO Xiang, ZHANG Shiyong, XIA Dinghui
2018, 43(5): 77-83.   doi: 10.13442/j.gnss.1008-9268.2018.05.015
[Abstract](661) [PDF 648KB](182)
摘要:
Precision Analysis of Single Point Positioning Model with GPS/GLONASS/BDS
WANG TAO
2017, 42(3): 32-37.   doi: 10.13442/j.gnss.1008-9268.2017.03.007
[Abstract](667) [PDF 618KB](78)
摘要:
The Method of Comparative Analysis Sliding and Non Sliding GPS Precise Ephemeris Interpolation
XU Wei, JIA Xue, YAN Chao, LIU Yang, DU Wenxuan, WANG Tao
2017, 42(2): 15-20.   doi: 10.13442/j.gnss.1008-9268.2017.02.004
[Abstract](349) [PDF 668KB](68)
摘要:
Positioning Performance Comparison and Analysis on BDS Dual and Triple Frequency Static Precise Point Positioning
2017, 42(1): 53-58.   doi: 10.13442/j.gnss.1008-9268.2017.01.011
[Abstract](329) [PDF 678KB](117)
摘要:
  Performance Analysis of GPS/BDS/GALILEO Multi-system Combination Pseudo-range Point Positioning
JIA Xue, XU Wei
2017, 42(6): 16-23.   doi: 10.13442/j.gnss.1008-9268.2017.06.003
[Abstract](776) [PDF 2113KB](122)
摘要:
Construction and development of satellite navigation augmentation systems
GUO Shuren, LIU Cheng, GAO Weiguang, LU Jun
2019, 44(2): 1-12.   doi: DOI:10.13442/j.gnss.1008-9268.2019.02.001
[Abstract](1227) [PDF 1536KB](69)
Abstract:
Since the birth of satellite navigation system, a variety of enhancement technologies and means are developed, and a large number of enhancement systems are established to meet the needs of users with higher accuracy and integrity. However, as a matter of fact, they are generated  later than the basic system and built independently on the respective demands, there are problems of “fragmentation” and “patch”  development, functional overlap with each other, lack of unified planning and standards, and unsystematic construction. This paper reviews and summarizes the generation and development process of satellite navigation augmentation technology, combings the relevant technical connotation and definition, and focuses on the related construction and development of China BeiDou Satellite navigation system augmentation system. On this basis, combined with emerging technologies such as 5G communication and loworbit satellites, the future development of satellite navigation augmentation system is prospected and analyzed.  Finally, suggestions are made for the augmentation system construction of the future BeiDou positioning, navigation and timing (PNT) comprehensive service.
Performance Analysis Joint of GPS/GLONASS/Galileo Precise Point Positioning Under Occlusion Condition
TIAN Xiancai, ZHAO Xingwang, XU Miaoqiang
2018, 43(6): 8-13.   doi: doi:10.13442/j.gnss.1008-9268.2018.06.002
[Abstract](1001) [PDF 62945KB](106)
Abstract:
For poor precision single point positioning performance of single GPS system under Occlusion Condition,to improve performance of precision single point positioning cross multisystem in this paper, By setting different Elevation mask angle, the environment around the city is divided into normal environment, general occlusion and heavy occlusion. Using GPS, GPS/GLONASS, GPS/Galileo, GPS/GLONASS/Galileo different modes respectively, the static PPP simulation experiments were carried out on four continuously operating reference stations in hong kong under the environment. the results show that multisystem combination can effectively remedy the shortage of satellites in the occlusion environment around the city, and the PPP performance of GPS/GLONASS, GPS/Galileo, GPS/GLONASS/Galileo combination is improved to varying degrees compared with that of a single GPS system.

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](1044) [PDF 1146KB](76)
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 Progress and Prospect of PPP/INS Integration System
WANG Haoyuan, SUN Fuping, XIAO Kai
2017, 42(5): 53-58.   doi: 10.13442/j.gnss.1008-9268.2017.05.011
[Abstract](978) [PDF 778KB](60)
Abstract:
With the construction of GNSS multi-system, precise point positioning (PPP) technology is developing in the direction of real-time and ambiguity-fixed solution. The PPP/INS integration system has a wide application prospect in the navigation and surveying field, since the convenience of not laying base station. In this paper, the contributions of GNSS multi-system, PPP ambiguity fixing, INS-aided to the PPP/INS integration system are systematically summarized. And the progresses of filtering method, smoothing algorithm and stochastic model establishment in integration system are generalized. The development trend of the PPP/INS integration system is discussed.
A novel engineering implementation technique for acquiring B1C signal in the BeiDou-3 receiver
YAN Shulin, DING Chao
2019, 44(1): 1-9.   doi: DOI:10.13442/j.gnss.1008-9268.2019.01.001
[Abstract](958) [PDF 1077KB](72)
Abstract:
The modern signals of the Chinese BeiDou-3 navigation system bring new features compared to the previous civilian signals, such as longer spreading code, involving secondary code, new modulation technique (i.e. Binary Offset Carrier BOC), data/pilot channels and so on. These innovations are able to enhance the signal acquisition robustness, but they also require specific acquisition techniques to handle the large data stream, deal with the problem of sign transition and side peaks caused by the secondary code and the BOC modulation respectively. This paper proposes a novel two-stage acquisition technique for realizing efficient acquisition of the B1C signal in the engineering implementation of the modern receiver. The first stage employs an extended parallelized Averaging Correlation (AC) search structure, which can cope with the sign transition problem, to coarsely capture the signal with high efficiency. At the second stage, a fine-search process is completed within a reduced searching range to provide high precision result. The involving of the later stage aims to avoid the side peaks effect in the tracking stage that can easily cause a false lock. In addition, both of the single and channel combining acquisition techniques are introduced, which give designers an option of implementing the acquisition with higher sensitivity but more resources. The experiment results demonstrate that the proposed method allows to use much cheaper FFT blocks and enables fast acquisition by parallel process. The proposed method can reduce the number of multiplications by at least 61% when the sampling frequency is over 50 MHz while providing quite similar acquisition precisions with the conventional method.

Bimonthly, Established 1976

Sponsored by:China Institute of Radio Transmission

Competent Authorities:China Electronics Technology Group Corporation

ISSN 1008-9268

CN 41-1317/TN