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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Development status and trend of international satellite based augmentation systems
SHAO Bo, DING Qun, ZHANG Jian, LI Pingli, WU Xianbing
 doi: 10.12265/j.gnss.2024104
[Abstract](9) [FullText HTML](6) [PDF 2244KB](0)
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In order to promote the application of GNSS in the field of high life-safety, augmentation means, represented by Satellite Based Augmentation Systems (SBAS), have emerged to comprehensively improve the accuracy, integrity, continuity and availability of GNSS service. The United States, Europe, Japan and other countries have started the SBAS performance improvement work, from single frequency SBAS to dual-frequency SBAS transition, to further improve SBAS performance. This paper summarizes the system composition, service performance, system progress and follow-up development planning of the international SBASs, and focuses on the system architecture, service capability, application verification and internationalization process of BeiDou Satellite-based Augmentation System (BDSBAS). With the implementation of the latest International Civil Aviation Organization(ICAO) Annex 10 to the Convention on International Civil Aviation, BDSBAS has become an internationally recognized provider of SBAS service. Subsequently, to promote the application of BDSBAS in the field of high life safety, it is necessary to complete the verification of civil aviation applications as soon as possible, so that BDSBAS can be included in the official services.
Research on tropospheric refractivity prediction method based on BP neural network
QIAN Zhigang, YANG Dongsheng, GUO Xiaotong, LI Xue
 doi: 10.12265/j.gnss.2024043
[Abstract](12) [FullText HTML](8) [PDF 2374KB](0)
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For satellite navigation systems, positioning errors are affected by the refractive index of the troposphere atmosphere. Improving the accuracy of predicting the refractive index of the troposphere atmosphere can reduce navigation positioning errors. The refractivity of tropospheric atmosphere is the main parameter for studying the influence of the troposphere on the propagation of electromagnetic waves, and the accuracy of its predictions is of great significance for radio systems. In this paper, a tropospheric refractivity prediction method based on BP neural network is proposed, which takes the year, month, day, time, surface refractivity, and altitude as the input of the BP neural network, and the corresponding refractivity at the input altitude as the output of the model. Similarly, by adjusting the input and output parameters, the BP neural network can also be used to predict the refractivity gradient of 1 km near the ground. Finally, the proposed algorithm is calculated and analyzed by using the historical aerial exploration data of Hongkong and Taiyuan, and compared with the methods in the existing papers. The results show that the proposed method has certain advantage in the calculation accuracy.
Precision orbit determination research of LEO satellite simulated downlink data
WANG Qining, WANG Le, LAI Wen, SHE Haonan
 doi: 10.12265/j.gnss.2024148
[Abstract](15) [FullText HTML](2) [PDF 2984KB](0)
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This study focuses on precision orbit determination utilizing simulated downlink data from low earth orbit (LEO) satellites. A comprehensive investigation is conducted on the orbit determination performance, considering a simulated Walker 90/10/1 LEO satellite constellation with an orbit altitude of 1 000 km and an inclination angle of 48°, along with 150 ground stations equipped with corresponding orbit clocks and observation data. The observational data from global station networks, featuring station numbers ranging from 60 to 150, are utilized for precise orbit determination of LEO satellites, followed by a detailed analysis of orbit accuracy and station position dilution of precision (SPDOP) values. Results indicate a significant enhancement in LEO satellite orbit accuracy from 117.5 mm to 39.8 mm upon increasing the number of stations from 60 to 150. Furthermore, sparse station distribution leads to a rapid degradation in LEO satellite orbit accuracy. The study underscores the effectiveness of augmenting the number of ground stations in improving both visible station SPDOP and LEO satellite orbit accuracy over terrestrial regions. However, due to the constrained tracking range of stations, enhancing the orbit accuracy of LEO satellites in marine regions remains challenging.
A clock synchronization/calibration system combining EKF and LSTM neural networks
XU Tao, GUO Chenyu, ZHAO Cheng
 doi: 10.12265/j.gnss.2024083
[Abstract](12) [FullText HTML](6) [PDF 2827KB](0)
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Research on methods to improve the timing accuracy and timekeeping capability of timing signals under satellite timing. By using a crystal oscillator counter, the crystal frequency information at the moment of each second pulse is recorded; the recorded historical information is input into an extended Kalman filter (EKF) for filtering, to eliminate the random error of the satellite second pulse signal, and extract the accumulated time of the first $N$ seconds of the BeiDou satellite pulse ${t_{CN}}$, and the crystal oscillator frequency $fre(k)$ at time $k$; and the crystal oscillator change rate $v(k)$ at time $k$; and the historical data output by the EKF is used as the training set, input into the long short-term memory (LSTM) network to establish a prediction model; the algorithm parameters are debugged using the control variable method to find the most suitable prediction model. The experimental results show that the maximum error of the timing signal output by the timing algorithm is 34 ns; the cumulative error of the timing algorithm in 8 hours is 1.001 μs, and the average error is less than 0.125 μs/h. This effectively improves the timing and timekeeping accuracy of the system.
Correction of ionospheric correction deviation in network RTK based on conditional adjustment
SHI Xin, ZHANG Xi, CHENG Bing, KE Yuanying, LEI Chuanjin
 doi: 10.12265/j.gnss.2024069
[Abstract](12) [FullText HTML](5) [PDF 3035KB](0)
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Aiming at the problem of low accuracy of ionospheric delay modelling in the afternoon in network RTK, a deviation correction method for ionospheric correction values based on conditional adjustment is proposed, using the condition that the theoretical closure difference of the three baselines in the triangle with double-difference ionospheric delays is 0, to adjust the ionospheric correction values obtained by modelling, and the scheme of determining the weighting array in the correction process is discussed. The experiments show that the correction algorithm can effectively improve the accuracy of ionospheric correction when the accuracy of the ionospheric correction model is not high, and at the same time, the determination of the weight array based on the ambiguity fixing of the known baselines can achieve a better correction effect, with the maximum value of the deviation of the ionospheric correction value reduced by 58.0 percent and the overall accuracy improved by 51.1 percent.
CAT II/III precision approach guidance flight verification at xianyang airport based on domestic GBAS
HAO Shuo, YU Baoguo, GE Mao, WANG Jiachen, WANG Yao, ZHAO Jingbo
 doi: 10.12265/j.gnss.2024091
[Abstract](25) [FullText HTML](12) [PDF 6432KB](0)
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Ground-Based Augmentation System (GBAS) can improve the accuracy, integrity , continuity and availability of satellite navigation, making it possible for aircraft to achieve safe and efficient approach and landing in complex weather and harsh environment, which can meet the high-precision navigation needs of civil aviation such as precision approach and landing guidance. At present, the GBAS Category I (CAT-I) service level has been verified and applied, but its service level, such as positioning accuracy, still can’t fully meet the needs of civil aviation. The technology and application of GBAS Category II/III (CAT II/III), which have better service level, are still under development and validation. In order to improve the efficiency and safety of civil aviation operations, there is an urgent need to carry out flight verification activities based on CAT II/III. Currently, GBAS is mainly based on single-frequency GPS, which is very limited in terms of system availability, safety and autonomy, so it is necessary to develop an autonomous and controllable GBAS system which is compatible with BDS. This article designs a flight verification scheme, which has completed the GBAS flight verification for CAT II/III blind approach and landing guidance at Xi'an Xianyang Airport by using the domestic GBAS system. The test results show that GBAS compatible with BDS has the ability to support CAT II/III precision approach and its performance is far superior to the traditional instrument landing system. This achievement provides a strong guarantee for the safety of air transporation in China.
Performance evaluation method and flight test analysis of BeiDou satellite-based augmentation dual-frequency service
WANG Ershen, CHEN Yitong, YU Tengli, ZHANG Jian, YANG Jian, XU Song, WANG Yongkang
 doi: 10.12265/j.gnss.2024087
[Abstract](26) [FullText HTML](15) [PDF 15305KB](0)
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The BeiDou satellite-based augmentation system (BDSBAS) realizes simultaneous augmentation of multiple satellite constellations by broadcasting dual-frequency augmentation messages through B2a signal to provide users with more accurate and reliable positioning and navigation services. In order to meet the demand of civil aviation for the positioning performance of BDSBAS in the approach phase, this paper researches the BeiDou satellite-based augmentation dual-frequency positioning algorithm, and evaluates the performance of the dual-frequency service of BDSBAS based on the data of the static station and the flight data in terms of the accuracy and integrity. The static experiment data were collected from the BDSBAS site in Beijing on January 17, 2024, for the whole day. The flight measurement data were collected from the aviation test conducted at Faku Caihu General Aviation Airport in Shenyang. The static evaluation results show that the positioning errors of Beijing, Xi’an and Jiayuguan stations were relatively stable during the evaluation period. The horizontal positioning accuracy(95%) was better than 2 m; the vertical positioning accuracy(95%) was better than 3 m. Horizontal availability was better than 99.998% and vertical availability was better than 99.984%. The results of the flight test show that the horizontal and vertical accuracy during the test were 1.8269 m and 2.6014 m, respectively, and no integrity event occurred. The static and dynamic evaluation results met the requirements of the International Civil Aviation Organization (ICAO) APV-I indexes for accuracy and integrity. The results of this study are meaningful for the performance evaluation of BDSBAS.
Research on code noise and multipath error processing methods of Satellite-based augmented system
ZHANG Jian, SHAO Bo, DING Qun, LI Pingli, WU Xianbing
 doi: 10.12265/j.gnss.2024103
[Abstract](23) [FullText HTML](12) [PDF 2050KB](0)
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The Satellite Based Augmentation System (SBAS) uses the pseudorange measurement corrections to enhance the integrity of navigation satellites, the code noise and multipath error processing accuracy are important factors affecting the service performance of the system and the accuracy of user positioning. In this paper, three different methods for dealing with raw pseudorange code noise and multipath error are introduced, including the single-frequency smoothing method, the code noise and multi-path correction (CNMC), and the code noise multipath method (CNMP) used by the Wide Area Augmentation System (WAAS). Through the data of the satellite-based augmentation system in operation, the influence of different code noise multipath error methods on the user’s positioning accuracy is verified. The results show that CNMP can effectively eliminate the influence of code noise and multipath error in the service performance evaluation of satellite-based augmentation system, and the horizontal accuracy of 95% is increased by 0.2 m, and the vertical positioning accuracy of 95% is increased by 0.47 m.
Review of SBAS authentication techniques
SONG Jiangyao, CHEN Xiao, LIU Ting, WU Zhongwang
 doi: 10.12265/j.gnss.2024123
[Abstract](15) [FullText HTML](10) [PDF 2292KB](0)
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In response to the threat of vulnerability of satellite navigation systems to spoofing, which will seriously affect the impact of navigation, positioning and timing services. How to enhance the security of navigation system services has become one of the issues that need to be addressed in satellite navigation services. Satellite navigation signal authentication is an emerging technical means to enhance civil signal anti-spoofing in satellite navigation systems, and it is also one of the important development directions and research hotspots of major satellite navigation systems at present. As the core augmentation system of the satellite navigation system, the satellite-based augmentation system (SBAS) system is currently promoting the SBAS message authentication standard under the framework of the International Civil Aviation Organization (ICAO) with a view to providing SBAS message authentication service in the future. Along with the completion of the construction of China’s BeiDou satellite-based augmentation system and the design and development of the next-generation BeiDou navigation system, the BeiDou satellite-based augmentation system needs to consider the provision of SBAS message authentication services under the framework of ICAO standards, in order to provide users with more secure and trustworthy PNT services. This paper firstly elaborates on the concept of SBAS message authentication, then combs through the development history of SBAS message authentication, and then analyzes the hot issues faced by SBAS message authentication technology, which will provide technical support for the subsequent message authentication service of BeiDou satellite-based augmentation system.
The design research of intelligent operation and maintenance monitoring platform for road, port and navigation based on BeiDou System
YAN Ying, ZHOU Yukai, WANG Jian
 doi: 10.12265/j.gnss.2024050
[Abstract](16) [FullText HTML](9) [PDF 2092KB](0)
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As the road and port shipping industry continue to develop and the scale of operations expands, efficient operation and maintenance monitoring is crucial to ensure the safety and operational efficiency of the entire logistics chain. This study proposes a design solution for a road and port shipping intelligent operation and maintenance monitoring platform based on the BeiDou Navigation Satellite System (BDS), aimed at enhancing the efficiency and safety of road and port shipping operations. Using the positioning and communication capabilities of BDS, integrating advanced sensors and internet of things technology to achieve real-time monitoring and management of ships, vehicles, and equipment and providing related data analysis and decision support functions. Effectively enhancing visualization and tracking capabilities during transport, ensuring stable information exchange under harsh conditions; At the same time, a large amount of operation and maintenance data is analyzed and processed in real time using integrated big data technology, improving the proactivity and accuracy of risk prevention and management. This effectively solves the core problems faced by the road and port shipping industry in operation and maintenance monitoring, contributing to the development of the transportation industry towards a more efficient, safer and more intelligent direction. This paper specifically studies and explores the construction principles of the intelligent operation and maintenance monitoring system, platform construction solutions, data service platforms, and geographic information platforms, achieving a comprehensive, multi-dimensional intelligent operation and maintenance solution based on BeiDou, enhancing the efficiency and safety of entire road and port shipping operations.
Research on precipitable water vapor prediction method based on lightGBM algorithm
LU Houxian, LI Kai, LI Li, HE Qimin, YU Hang, DONG Zhounan
 doi: 10.12265/j.gnss.2024079
[Abstract](18) [FullText HTML](9) [PDF 4113KB](0)
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The precipitable water vapor (PWV) represents the content of liquid water vapor in a unit cross-sectional area vertically from the Earth's surface to the top of the troposphere, reflecting the concentration of water vapor in the atmosphere. In this study, data from seven radiosondes in the Yangtze River Delta region from 2014 to 2019 were utilized to analyze the correlations between PWV and zenith tropospheric delay (ZTD), zenith hydrostatic delay (ZHD), zenith wet delay (ZWD), water vapor pressure (Es), atmospheric pressure (Ps), surface temperature (Ts), and weighted mean temperature (Tm). A new Light Gradient Boosting Machine (LightGBM)-based PWV prediction model for the Yangtze River Delta region was established, and then the prediction accuracy of the LightGBM-PWV model was analyzed. The results show that the correlation coefficients (R) between PWV and Tm, Ts, Ps, Es, ZHD, ZWD, and ZTD were 0.74, 0.76, –0.59, 0.76, –0.43, 1.00, and 0.94 respectively. The average biases of the yearly, seasonal, and monthly LightGBM-PWV model were 0.10 mm, 0.11 mm, and 0.12 mm respectively, and their RMSE are 0.25 mm, 0.26 mm, and 0.31 mm. The accuracy of the yearly, seasonal, and monthly LightGBM-PWV model decreased sequentially, different from the traditional linear fitting PWV models. The yearly LightGBM-PWV forecasting models demonstrate the highest accuracy. It can be applied for the GNSS-PWV forecasting, analysis, and research in the Yangtze River Delta region.
Improvement of ionospheric availability for Beidou satellite-based augmentation system based on SHAKING method
LIU Ang, LI Zishen, WANG Ningbo, ZHANG Zhouyu, WANG Liang, SHAO Bo
 doi: 10.12265/j.gnss.2024076
[Abstract](32) [FullText HTML](17) [PDF 3174KB](1)
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The BeiDou Satellite-Based Augmentation System (BDSBAS) provides ionospheric correction and integrity monitoring services for users in China and surrounding regions through domestic monitoring stations. Therefore, it demands high availability of ionospheric algorithms. This paper utilizes the adjusted Spherical Harmonics Adding Kriging (SHAKING) method to calculate ionospheric parameter information for BDSBAS. Performance analysis of existing SBAS ionospheric models reveals that some SBAS systems broadcast delay correction information marked as unmonitored points. Demand analysis of regional SBAS grid points in China shows that when the satellite elevation angle is set as 15°, SHAKING provides 189 usable points and 3 unusable points. Combined with clock and orbit correction information provided by BDSBAS, SHAKING improves the availability range of Approaches with Vertical Guidance by approximately 30% compared to the Inverse Distance Weighting (IDW) method.
A random forest-based prediction model for ionospheric foF2 in China and surrounding regions
LIN Ziyang, CHEN Longjiang, JIN Ruimin, OU Ming, YANG Huiyun, JI Guangwang, CUI Xiang, GU Mingyue
 doi: 10.12265/j.gnss.2024140
[Abstract](27) [FullText HTML](10) [PDF 3378KB](2)
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The square of the critical frequency of the ionospheric F2 layer (foF2) is proportional to the peak electron density (NmF2) and serves as a crucial parameter affecting the performance of Global Navigation Satellite Systems (GNSS). Enhancing the prediction accuracy of foF2 is essential for optimizing GNSS broadcast ionospheric models, thereby improving the positioning accuracy of GNSS. This study develops an ionospheric foF2 prediction model for China and its surrounding regions using the random forest algorithm, based on data from 18 ionosonde stations of the China Research Institute of Radiowave Propagation and COSMIC occultation observations. The model incorporates multiple features, including Universal Time, day of the year, geographic location, solar, and geomagnetic activities. A comparative analysis with the International Reference Ionosphere (IRI-2020) model validates the prediction accuracy of our model. The results indicate that the random forest model reduces the mean absolute error by 14.81% and 17.11%, and the root mean square error by 11.21% and 13.14%, compared to the IRI CCIR and IRI URSI models, respectively. Additionally, the model exhibits superior prediction accuracy under various latitudes, local times, solar, and geomagnetic activity conditions when compared to IRI-2020. This research not only significantly enhances the foF2 prediction accuracy for China and its surrounding regions but also lays a critical foundation for improving the accuracy and reliability of GNSS globally.
Research on roll angle estimation method based on deep learning
FENG Lu, WU Peng, ZHENG Yu, ZHANG Zhuxian
 doi: 10.12265/j.gnss.2024078
[Abstract](22) [FullText HTML](17) [PDF 3330KB](0)
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Attitude measurement technology serves as a fundamental component in monitoring vehicle motion states and ensuring safety. The spinning motion of vehicles leads to a coupling of attitude angles, which significantly impacts flight control. In this paper, a deep learning approach based on the Long Short-Term Memory (LSTM) neural network is proposed to determine the real-time roll angle of a vehicle. The energy characteristics exhibited by a single antenna receiving satellite signals during the vehicle's rolling state have been analyzed in detail. A correlation between the real-time roll angle and the energy amplitude of the received signal has been established. The influence of changing satellite positions on these measurements is also discussed. Subsequently, the LSTM neural network training method is employed to extract periodic variation features from the measured signals, thereby obtaining various network parameters. These parameters are then used to predict and denoise the received signal, with the roll angle being computed by model matching. To validate the efficacy of the proposed method, a rolling experiment was conducted. The experimental results demonstrate that the LSTM-based deep learning approach effectively restores the features of the received signals, enabling accurate real-time measurement of the vehicle's roll angle.
Analysis of extreme rainfall characteristics of Datong “817” based on BDS-3 and FY-4A
ZHAO Lijiang, ZHAO Jianyun
 doi: 10.12265/j.gnss.2024067
[Abstract](37) [FullText HTML](12) [PDF 5341KB](0)
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Adequate water vapor and cloud phase changes are two necessary conditions for rainfall to occur. Based on the BeiDou-3 satellite navigation system, water vapor can be retrieved, which has the advantages of high time resolution and accuracy; FY-4A can provide cloud phase parameters with a resolution of 15 minutes. This article uses the BDS-3 and FY-4A data to analyze the spatiotemporal changes in atmospheric precipitation and cloud phase before and after the occurrence of all precipitation in August 2022. Through comparison, three characteristics of extreme rainfall in Datong “817” were obtained: firstly, the atmospheric precipitation rapidly increased one hour before rainfall, reaching a rate of 3.17 mm/h, significantly exceeding the general rainfall level of the same period; before the second rainfall, there were multiple changes in cloud types between multi-layer clouds and opaque ice clouds, and eventually extreme rainfall occurred in the form of opaque ice clouds; the third reason is that the height of extreme rainfall cloud tops is usually greater than 10000 meters.
Analysis of the impact and effects of the solar storm on the ionosphere from May 8 to 16, 2024
WANG Shuai, QUAN Lin, LI Ling, WANG Kunpeng, HUANG Jian, YUAN Gang
 doi: 10.12265/j.gnss.2024107
[Abstract](116) [FullText HTML](43) [PDF 5661KB](8)
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Solar storms can cause severe disturbances to the state of Earth’s ionosphere and affect navigation and positioning performance. According to the ionospheric disturbance event occurring during the solar storm from May 8 to 16, 2024, the changes of ionospheric total electron content, ionospheric total electron content change rate, ionospheric F2 layer critical frequency, satellite navigation single point positioning error and so on at different latitude stations in the eastern and western hemispheres are analyzed. The analysis result shows that the sun-lit hermisphere of the ionosphere will respond to X-ray flares, but the main source of the disturbance is the geomagnetic storm caused by the solar wind southward magnetic field energy injection. The responses at the top and bottom of the ionosphere during solar storms are not synchronized; The single point positioning error of satellite navigation will increase significantly during the solar storm, especially in the vertical direction it will increase to about ±10 m. It will continue to exist during the recovery phase of ionospheric storms, and gradually weaken with the calm of the ionospheric state.
Application research of RINGO software in multi-system GNSS data preprocessing
FAN Jiuguo, LI Jianyong
 doi: 10.12265/j.gnss.2023202
[Abstract](360) [FullText HTML](136) [PDF 4282KB](50)
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Data preprocessing is a prerequisite for achieving high-precision positioning with the Global Navigation Satellite System (GNSS) and is also a vital step in data processing. As the number of satellite systems, numbers, and versions of Receiver Independent EXchange format (RINEX) increase, the GNSS data types and formats become progressively complex. Thought there are various data preprocessing software options available, multiple programs are required to complete the preprocessing stage, resulting in inefficiency and complexity. Therefore, to achieve efficient data preprocessing, developers have created the “RINGO” data preprocessing software, which supports all RINEX versions of multi-system data preprocessing. To achieve effective data preprocessing, developers created the “RINGO” software which supports all RINEX versions of multi-system data preprocessing. The study demonstrates the main functions, usage and principles of RINGO, with a focus on investigating and explaining confusing functions such as receiver clock jump correction. The test results demonstrate that RINGO can effectively and independently preprocess vast amounts of multi-system GNSS data, which can significantly ease the complex task of GNSS data management and foster the adoption of the latest version of RINEX observation records.
Architecture design of radiation source positioning system based on TDOA
HU Anyi, WANG Dengliang, QIN Bingkun, ZHANG Faxiang
 doi: 10.12265/j.gnss.2023174
[Abstract](169) [FullText HTML](120) [PDF 2726KB](17)
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To ensure the normal application of the Global Navigation Satellite System (GNSS), monitoring and localization of GNSS interference radiation sources are required. This paper presents the design of a radiation source positioning system architecture. By designing the system functions, architecture, grid monitoring equipment and workflows, high-precision time synchronization and reliable time difference measurements are achieved using BeiDou/GPS timing + high-stability crystal oscillators and a generalized weighted time delay estimation algorithm, which ensures the accuracy of time difference of arrival (TDOA) localization. The effective location of radiation source is realized through system application test.
2024, 49(4).  
[Abstract](90) [FullText HTML](62) [PDF 1297KB](23)
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Special Issue on “Satellite Navigation Information Security”
2024, 49(4): 1-1.  
[Abstract](92) [FullText HTML](54) [PDF 1668KB](8)
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2024, 49(4): 2-2.  
[Abstract](73) [FullText HTML](38) [PDF 1432KB](8)
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Design of satellite navigation service performance evaluation and interference monitoring protection system
LI Teng, JIANG Dongwei, LI Jinlong, HU Xiaoping
2024, 49(4): 3-9.   doi: 10.12265/j.gnss.2024113
[Abstract](164) [FullText HTML](52) [PDF 2130KB](14)
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The satellite navigation signals have inherent vulnerabilities and are highly susceptible to both intentional and unintentional electromagnetic interference. Therefore, conducting monitoring and evaluation of satellite navigation service performance and interference signals is of significant importance for supporting the operational services of navigation systems and ensuring the security of spatio-temporal information applications. This paper addresses the mechanisms and characteristics of monitoring and evaluating satellite navigation service performance. In conjunction with the practical needs for interference monitoring and troubleshooting, it presents an overall architecture for system construction and operational processes. Furthermore, it conducts research and analysis on the key technologies necessary for enhancing system effectiveness, providing comprehensive guidance and technical support for the engineering construction of a navigation application monitoring and support system characterized by “multi-source integration, wide-area coverage, three-dimensional perception, and rapid response”.
Differential privacy-based cooperative positioning for satellite internet
TAO Yihang, LI Jianhua
2024, 49(4): 22-27.   doi: 10.12265/j.gnss.2024032
[Abstract](166) [FullText HTML](56) [PDF 2316KB](18)
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Satellite internet provides positioning, navigation and timing services for the whole world based on the Global Navigation Satellite System (GNSS), but the data containing users’ location information will be leaked during GNSS cooperative positioning process, which poses a threat to users’ privacy security. To address the current privacy-protection challenges in GNSS cooperative positioning systems, this paper proposes a differential privacy-based cooperative positioning method for GNSS systems. The method first generates the perturbed position and randomly selects one to calculate the positioning collaboration data under the premise of satisfying the privacy budget, so as to prevent the user’s location from being leaked during the collaboration process. The experimental results show that the proposed method can effectively protect user location privacy while guaranteeing real-time and accurate positioning service, which provides a theoretical reference for the research of GNSS cooperative positioning information security.
An optimized deployment method for satellite navigation distributed suppression of interference
XIAO Yifan, LIU Weiping, YU Jiashu
2024, 49(4): 92-98.   doi: 10.12265/j.gnss.2024028
[Abstract](126) [FullText HTML](39) [PDF 2705KB](16)
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Satellite navigation has been widely used in various fields of human production and life, however, due to weak landing signals and other reasons, satellite navigation signals are prone to interference. In practical applications, distributed suppression jamming has become an effective means of satellite navigation jamming because of its advantages such as large coverage area and difficult detection. In this paper, the visual field algorithm based on the reference surface is used to calculate the interference range of a single jamming station in a specific terrain, and on this basis, a cyclic iterative method is used to find the optimal layout scheme of distributed jamming suppression. Experimental analysis shows that under experimental conditions, the distributed suppression interference coverage rate of the proposed method is more than 98%, which is obviously better than 74.18% of the traditional high-power single interference source. At the same time, the key suppression interference targets can be further highlighted and multiple suppression interference can be realized by setting red and green zones reasonably.
Maritime rescue terminal based on BDS short message and emergency position indicating radio beacon
MA Jun, NIE Guigen, LIAO Mi, GAO Wenliang
2024, 49(4): 107-112.   doi: 10.12265/j.gnss.2024057
[Abstract](94) [FullText HTML](50) [PDF 2310KB](10)
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Traditional maritime rescue terminals suffer from insufficient positioning accuracy and real-time performance. A maritime rescue terminal is designed for combines the functions of BDS short message and Emergency Position Indicating Radio Beacons (EPIRB). Combined with the command center and related software systems, it can achieve rapid reporting and precise positioning of distress. BeiDou Navigation Satellite System (BDS) short message communication can send messages between terminals and satellites. The COSPAS-SARSAT is an important component of the maritime distress search and rescue system implemented by the International Maritime Satellite Organization. It uses signals sent by EPIRB to locate accident locations and information. Combine the BDS short message with EPIRB, and assemble positioning modules and temperature, heart rate, and other sensors. When the holder is in danger, the terminal will immediately continuously send distress information to the command center, which can provide support for the rescue mission through analysis by the command center. After testing, its dynamic and static positioning accuracy has reached the level of 10 meters; BDS short message, EPIRB working well.
Localization for GNSS interference sources based on weighted K-Means combined with DRSS positioning
CHENG Hanqing, ZHANG Guomei, PENG Kejun
2024, 49(4): 113-120, 126.   doi: 10.12265/j.gnss.2024025
[Abstract](81) [FullText HTML](31) [PDF 2975KB](8)
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The carrier to noise ratio (CNR) based interference positioning in Global Navigation Satellite System (GNSS) has the problem of high localization difficulty and the low localization precision under the scenarios with multiple interference sources, multi-path transmission and long distance between receivers. Aiming at this problem, a multi-interference localization scheme that combines the weighted K-Means clustering with different receiver signal strength (DRSS) and equation solving based method is proposed in this paper. Assuming that the number of interference sources is determined and a single receiver is only affected by one interference source, the improved weighted K-Means clustering algorithm is designed to realize the initial estimation for multiple interference sources. In order to reduce the positioning error of the weighted K-Means clustering when the distance between receives is long, the receiving CNR affected more obviously by interference within each cluster are used to build the localization equations based on DRSS after clustering processing. To solve the equations can obtain the more accurate localization results. Simulation results demonstrate that the proposed scheme can realize the multi-interference localization. Compared with the scheme only including weighted K-Means, the average positioning errors of the proposed method involving DRSS parameters can be reduced by more than 19% and 38% under the two cases of single source and two single-tone sources, respectively.
Special Issue on “Satellite Navigation Information Security”
Introduction of ICG IDM and technology analysis of GNSS interference detection and localization
JIN Ruimin, ZHEN Weimin, HAN Chao, CHEN Li, CHEN Qidong, YANG Huiyun, CUI Xiang, GU Mingyue
2024, 49(4): 10-21.   doi: 10.12265/j.gnss.2024039
[Abstract](156) [FullText HTML](47) [PDF 3256KB](16)
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Global Navigation Satellite System (GNSS) is widely used in all walks of life. However, GNSS signals are very weak and the civilian signal format is known, making it extremely susceptible to various intentional and unintentional electromagnetic interferences, which poses a serious threat to GNSS applications. GNSS interference has attracted widespread international attention, the International Committee on Global Satellite Navigation Systems (ICG) has established a special GNSS interference detection and mitigation (IDM) working group to develop IDM technologies and exchange ideas on IDM system construction. This paper introduces the situation of ICG IDM, and analyzes the research progress of GNSS interference detection and localization technology and IDM systems. It provides important technical reference and research support for deepening the theoretical and technical research on GNSS interference monitoring and ensuring the safety of satellite navigation.
Research on the application of navigation countermeasures in the Russia-Ukraine Conflict
JIA Zanjie, YU Heli, WU Zhijia, DAI Taogao
2024, 49(4): 28-33, 41.   doi: 10.12265/j.gnss.2024026
[Abstract](129) [FullText HTML](80) [PDF 4320KB](30)
Abstract:
The Russia-Ukraine Conflict is one of the major hotspot of the international situation. This paper reviews the situation of Russia and Ukraine navigation countermeasure equipment. Based on the IGS monitoring data near the conflict area and the military actions of Russia and Ukraine, this paper analysis the measures taken by Russia and Ukraine to fight for control of navigation resources in the conflict, and deeply studied the application methods of navigation confrontation between the two sides. Through analysis, it can be concluded that satellite navigation signals in conflict zones are one of the important sources of battlefield intelligence. Combined with other reconnaissance methods, comprehensive analysis and judgment can comprehensively reflect the military dynamics of the battlefield.
GNSS interference localization technology using the carrier-to-noise ratio measurements of the receivers
LIU Zhijian, YAO Zhiqiang, DENG Min, PENG Deyi, JIANG Fan
2024, 49(4): 34-41.   doi: 10.12265/j.gnss.2024033
[Abstract](191) [FullText HTML](39) [PDF 2609KB](24)
Abstract:
Due to the low signal strength of GNSS signals upon reaching the ground, they are highly susceptible to unintentional or intentional human interference, which can severely impact the availability of navigation and positioning services. Therefore, locating and eliminating sources is of paramount interference. For common jamming interference, current positioning methods mainly involve processing the raw sampled signals, which often leads to issues with complex equipment, high computational demands, and high costs. This paper proposes a method for locating GNSS interference source using the carrier-to-noise ratio (C/N0) measurements from standard commercial receivers. By estimating the interference signal strength difference through C/N0 measurements, the position of the interference source can be calculated. Field test results indicate that, under line-of-sight conditions, in a monitoring area of approximately 11 400 square meters, this method can achieve a Mean Absolute Error (MAE) of 13.17 meters with minimal time consumption, thereby effectively locating the interference source. The proposed method does not require any modifications to the receiver's hardware or software, making it simple to implement and cost-effective, which is advantageous for engineering applications.
Analyzing the security of RDSS system from the perspective of information security
ZHANG Tao, NIE Guigen, MA Jun
2024, 49(4): 42-47.   doi: 10.12265/j.gnss.2024055
[Abstract](103) [FullText HTML](31) [PDF 2732KB](12)
Abstract:
This paper analyzes the security advantages of radio determination satellite service (RDSS) in terms of signal structure and operation mechanism, and studies the potential security risks and countermeasures of RDSS from three aspects of information security: confidentiality, integrity, and availability. In particular, the use of radio frequency recording and replay (RAR) to verify the potential counterfeiting and deception security risks of RDSS has been studied prove that RDSS has vulnerabilities in resisting RAR attacks and is easily deceived by RAR attacks. The success of this deception attack exposes the security risks in the integrity and availability of the RDSS system, which can cause information confusion for end users and may also limit the frequency of attacks, preventing them from receiving normal services. Finally, several measures were proposed to improve system security in response to such security risks.
Consistency deception detection technique for GNSS/INS based on open-closed-loop alternation
CHENG Yuyang, PENG Xinzhi, FENG Fan, XU Yiyu, YUAN Xuelin, ZHU Xiangwei
2024, 49(4): 48-55, 65.   doi: 10.12265/j.gnss.2024020
[Abstract](122) [FullText HTML](46) [PDF 3392KB](15)
Abstract:
The Global Navigation Satellite System (GNSS) and inertial navigation system (INS) are widely used in fields such as vehicles and drones. However, GNSS receivers are susceptible to deceptive signals. Therefore, this paper proposes a consistency deception detection technique using INS observations. Inertial devices have the characteristics of being less susceptible to deceptive signal interference and prone to cumulative errors. By alternately feeding back estimated errors in an open-closed loop manner, a GNSS/INS integrated navigation system is constructed. During the open-loop period, a deception detection window is established, and the consistency between the statistical detection measurements of the inertial device, acceleration, and angular velocity obtained from GNSS is evaluated to determine the presence of deception. Experimental results demonstrate that with a window time of 70 s, the detection probability reaches 99.2% while the false alarm probability is 5.2%.
A novel GNSS spoofing interference detection technology based on SQM
DENG Min, LIAO Xinlu, GUO Yingying, YAO Zhiqiang
2024, 49(4): 56-65.   doi: 10.12265/j.gnss.2024017
[Abstract](200) [FullText HTML](52) [PDF 3167KB](20)
Abstract:
The Global Navigation Satellite System (GNSS) plays a strategic role in positioning, navigation, and timing in infrastructure application. Given the characteristics of GNSS signals such as extremely low landing power and transparent civil code structure, civil satellite signals are extremely vulnerable to interference and spoofing attacks, which makes GNSS suffer from serious interference problems. In this paper, to address the problems of low detection probability and poor reliability of traditional SQM (signal quality monitoring) detection quantities, we propose a new type of SQM detection quantities without the carrier phase information of tracking loop. Then, the metric values are moving averaged to reduce the effect of abnormal fluctuation value on the false alarm probability. Besides, the statistical distribution characteristic of the proposed metric is derived. The computation threshold and measurement threshold without a priori information are set up. The proposed method can avoid the failure detection when the relative carrier phases of spoofing and authorized satellite navigation signal are integer multiples of π. The comparison experimental results based on the public database with real measured signals of TEXBAT (texas spoofing test battery) show that the proposed algorithm is able to detect spoofing attacks with better accuracy in a shorter time under different real signal scenarios. The research results are valuable for the development of anti-spoofing communication devices in the future to improve the detection performance effectively without making large-scale changes to the hardware structure of the receiver.
Research on GNSS spoofing interference detection for multi-correlator combined power
ZHAO Shen, LIAO Yifei, LI Shiling, ZHOU Kaijun
2024, 49(4): 66-74.   doi: 10.12265/j.gnss.2023235
[Abstract](127) [FullText HTML](34) [PDF 3548KB](13)
Abstract:
Global Navigation Satellite System (GNSS) civil signals are vulnerable to external spoofing because of their openness and vulnerability. As an effective method for spoofing detection, Signal Quality Monitoring (SQM) monitors the correlation results of early code, late code and phase code (ELP) after the receiver's tracking loop, and compares them with the correlation characteristics without spoofing to determine whether spoofing interference exists. The conventional SQM algorithm uses only three ELP information and the detection performance is limited. Therefore, a multi-correlator combined power algorithm is proposed. The weight of the output power of multiple equally spaced correlators between ELP is taken as the detection quantity, and the inverse ratio of the correlation time and the real-time code time difference is taken as the weighting coefficient. The probability distribution characteristics of the detected quantity were further analyzed, and the optimal detection threshold was determined based on the Neyman-Pearson theory. By comparing the detected quantity and the detection threshold, the existence of deception interference was determined. Based on the Scenario 4 set published by the University of Texas, the test results show that compared with typical SQM algorithms such as Ratio and ELP, the proposed algorithm has both high detection probability and fast early warning response time under different false alarm rates.
Anti-spoofing technology based on array antenna signal processing
LU Jianjun, PENG Xinzhi, FENG Fan, HUANG Chuhan, YUAN Xuelin, ZHU Xiangwei
2024, 49(4): 75-85.   doi: 10.12265/j.gnss.2024019
[Abstract](153) [FullText HTML](44) [PDF 2491KB](21)
Abstract:
Global navigation satellite systems play an important role in national infrastructure as well as life safety applications, but the increasing spoofing incidents pose a great threat to GNSS. This paper introduces the anti-spoofing technology based on array antenna signal processing, and summarizes the spoofing interference detection and spoofing interference suppression methods from both uniform and sparse arrays according to the different array configurations. Compared with uniform array, sparse array has larger array aperture and degree of freedom under the same number of antenna elements, which greatly reduces the cost of equipment, but its coherent signal processing technology requires more. Finally, this paper gives the difficulties faced by the anti-spoofing interference technology and its future development trend.
The time spoofing detection method based on Long Short-Term Memory network
SHENG Menggang, SHENG Siyuan, DENG Min, WANG Liliang, YAO Zhiqiang
2024, 49(4): 86-91.   doi: 10.12265/j.gnss.2024034
[Abstract](125) [FullText HTML](59) [PDF 2628KB](12)
Abstract:
Temporal and spatial information security is fundamental to the safety of national critical infrastructure. Disruption or interference with the time system can cause significant economic losses to the nation, and even pose a substantial threat to defense security. Existing timing deception detection methods primarily establish models based on the characteristics of changes in the receiver’s clock model to detect deception. However, due to the uncertainty of attack methods and the system errors inherent in the established receiver clock model calculation and fitting process, accurate fitting of the clock model parameters is difficult, and the environmental adaptability is low. To address this, this paper proposes a timing deception detection method based on the Long Short-Term Memory (LSTM) network. This method does not require consideration of the attack methods of timing deception, and has strong generalization capabilities. By utilizing the excellent time series prediction ability of LSTM, the method accurately tracks the trend of changes in receiver clock differences before and after timing deception based on the characteristics of these changes, achieving effective detection of timing deception interference. Finally, experiments and analyses are conducted using TEXBAT (Texas spoofing test battery) timing deception scenario data, and a comparison is made between LSTM and Multilayer Perceptron (MLP) networks. The results indicate that the performance of LSTM timing deception detection is superior to that of MLP.
Research on GNSS spoof detection method based on PCS combined with Ratio
ZHAO Shen, HU Yong, LI Shiling, XIA Yi
2024, 49(4): 99-106.   doi: 10.12265/j.gnss.2023234
[Abstract](104) [FullText HTML](48) [PDF 2994KB](11)
Abstract:
A spoofing detection algorithm based on power combind with signal quality montoring(PCS) combind with Ratio(PCSR) is proposed to improve the performance of spoofing detection, in response to the problem of high fluctuation in the detection performance of PCS during the traction stage. The fusion process of the PCSR algorithm uses a weighting factor to linearly weight the amplitudes of the processed PCS and Ratio, and adjusts the contribution of PCS and Ratio to PCSR by changing the weighting factor.The experiment used data scenario 4 (DS4) of texas spoofing test battery (TEXBAT) from the University of Texas at Austin as the dataset to compare and analyze the deception detection performance of PCS, Ratio, and PCSR algorithms. The experimental results show that PCSR has higher detection probability and accuracy, better immediacy and robustness, and a wider detection range. The proposed PCSR algorithm combines the advantages of both PCS and Ratio algorithms and has better spoofing detection performance.
Research on jamming methods of satellite navigation and positioning system in UAV defense
GENG Zeqi, YU Heli, JIA Zanjie, CAI Yong, TANG Bin
2024, 49(4): 121-126.   doi: 10.12265/j.gnss.2024068
[Abstract](130) [FullText HTML](49) [PDF 2560KB](24)
Abstract:
In view of the increasingly vicious UAV “black flight” phenomenon, and considering that its satellite navigation terminal will be loaded with multi-array adaptive zeroing anti-jamming antenna to improve the use of navigation resources, the advantages of using satellite navigation jamming for UAV defense are analyzed, and a satellite navigation jamming method for UAV defense is explored. The implementation strategy of navigation jamming from single interference source to multi-interference source is described, and the evaluation index is given. It helps protection personnel to accurately explore effective defense boundaries, determine weak areas, optimize interference source deployment strategies, and improve protection efficiency. A defense effect evaluation software is developed, which can present the defense situation and make the defense effect display more intuitive.
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](2450) [PDF 1536KB](1320)
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](1906) [PDF 1895KB](363)
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](1144) [PDF 750KB](218)
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](1710) [PDF 93258KB](338)
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](920) [PDF 678KB](174)
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](1030) [PDF 648KB](230)
摘要:
3D-coordinate interpolation for UAV high dynamic positioning based on cubic spline interpolation
GAO Xiao, YANG Zhiqiang, KU Xinbo, ZHENG Rong
2020, 45(1): 37-42.   doi: DOI:10.13442/j.gnss.1008-9268.2020.01.006
[Abstract](470) [PDF 664KB](103)
摘要:
A Survey of Fusion Algorithms for Multi-source Navigation Fusion System
TANG Luyang, TANG Xiaomei, LI Baiyu, LIU Xiaohui
2018, 43(3): 39-44.   doi: 10.13442/j.gnss.1008-9268.2018.03.007
[Abstract](988) [PDF 668KB](202)
摘要:
Effect of image control point layout on the accuracy of real-world modeling of small-scale irregular areas of UAVs
ZHANG Guangzu, WANG Chun, XU Yan, TAO Yu, WU Liang, SHENG Shuai
2020, 45(2): 60-67.   doi: DOI:10.13442/j.gnss.1008-9268.2020.02.010
[Abstract](311) [PDF 2013KB](87)
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](881) [PDF 476KB](157)
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](2450) [PDF 1536KB](361)
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](1935) [PDF 62945KB](225)
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](1664) [PDF 1146KB](200)
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.
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](1559) [PDF 1077KB](164)
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.
  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](1802) [PDF 778KB](219)
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.

Bimonthly, Established 1976

Sponsored by:China Institute of Radio Transmission

Competent Authorities:China Electronics Technology Group Corporation

ISSN 1008-9268

CN 41-1317/TN