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2022 Vol. 47, No. 4

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2022, 47(4)

[Abstract](115) [FullText HTML] (104) [PDF 2297KB](58)

Abstract:

Review of underwater navigation and positioning technology

ZHANG Tao, XIA Maodong, ZHANG Jiayu, ZHU Yongyun, TONG Jinwu

2022, 47(4): 1-16. doi: 10.12265/j.gnss.2022094

[Abstract](2902) [FullText HTML] (484) [PDF 2769KB](417)

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As the main carrier for the development and utilization of marine resources, autonomous underwater vehicles (AUV) need accurate positioning information when performing tasks. The main navigation mode of AUV is based on strap-down inertial navigation system (SINS), assisted by acoustic navigation and geophysical field matching. This paper introduces the basic principles, advantages and disadvantages and application scenarios of various underwater navigation modes. The key technologies of various navigation modes are researched to improve the precision and stability of integrated navigation. By analyzing the existing problems at present, the future development trend of underwater navigation is forecasted.

Improvement of legendre polynomial fitting algorithm for IGS precise ephemeris

SHEN Shaofei, LEI Weiwei, LI Zhennan

2022, 47(4): 17-22. doi: 10.12265/j.gnss.2022049

[Abstract](385) [FullText HTML] (126) [PDF 2304KB](40)

Abstract:
The International GNSS Service (IGS) precise ephemeris provides satellite coordinates every 15 minutes. In order to improve the positioning accuracy, it is often necessary to obtain the satellite position at any time. Interpolation and fitting of IGS precise ephemeris is a common method to obtain satellite coordinates of continuous epochs. The improved Legendre polynomial algorithm is used to fit the satellite orbit coordinates, and compared with the conventional algorithm. The results show that the conventional algorithm can maintain high accuracy only when the fitting order is low. When the fitting period is 6 h, LU decomposition method and singular value decomposition (SVD) method can maintain high accuracy in solving singular matrix, while when the fitting period is 12 h, SVD decomposition method decomposes the matrix ${\boldsymbol{B}}$ with low condition number to obtain polynomial coefficient ${\boldsymbol{C}}$, so as to avoid the error caused by ill conditioned matrix, so it can still maintain high accuracy. In high-order fitting, SVD decomposition method is superior to LU decomposition method and conventional algorithm in both accuracy and stability.

Comparative analysis of broadcast ephemeris accuracy before and after the opening of BDS-3 system

JING Xin, CHE Tongyu, ZHOU Shuhan, LI Jianwen

2022, 47(4): 23-30. doi: 10.12265/j.gnss.2022051

[Abstract](588) [FullText HTML] (110) [PDF 2921KB](74)

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BeiDou-3 Navigation Satellite System (BDS-3) has been in operation for more than one year. By studying the BeiDou Navigation Satellite System (BDS) broadcast ephemeris data from August 2019 to August 2021, the orbit, clock error and signal-inspace ranging error (SISRE) of BeiDou Navigation Satellite (regional) System (BDS-2) and BDS-3 satellites are analyzed by using the post precision ephemeris. The results show that after the BDS-3 system is opened, the satellite orbit accuracy is significantly higher than that of BDS-2. The radial error root mean square (RMS) value is improved from about 0.87 m to better than 0.23 m, the accuracy is improved by about 74%, and the 3D error RMS value is improved from less than 1.63 m to better than 0.75 m, the accuracy is improved by about 54%; The accuracy of hydrogen atomic clock and rubidium atomic clock is the same. The accuracy improvement of RMS value of BDS-3 clock error is basically the same as that of BDS-2, with an accuracy improvement of about 1 ns; In SISRE accuracy comparison, the RMS value of BDS-2 SISRE is increased from 0.9 m to 0.7 m, and BDS-3 SISRE is increased from 0.8 m to 0.5 m. through comprehensive comparison, the performance of BDS-3 system is greatly improved

Comprehensive performance analysis of BDS-3 precise point positioning time transfer

ZHAI Hongliang, WANG Shengli

2022, 47(4): 31-38. doi: 10.12265/j.gnss.2021101306

[Abstract](305) [FullText HTML] (86) [PDF 15446KB](43)

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The construction of China’s BeiDou-3 Navigation Satellite System (BDS-3) has been basically completed. Therefore, full use of the current BDS-3 satellite for precise point positioning (PPP) time transfer requires urgent research. This article analyzes BDS-3 PPP time transfer in two aspects. 1) BeiDou-2 Navigation Satellite System (BDS-2), BDS-3 and BDS-2+BDS-3 PPP time transfer. 2) Clock model constrained BDS-3 PPP time transfer. The results show that the root mean squares (RMS) values of smoothed residual value obtained by BDS-3 and BDS-2+BDS-3 PPP can be reduced by 34.5% and 38.23%, the frequency stability of 960 s is increased by 35.81% and 37.75% respectively, compared with BDS-2 PPP; compared with the traditional white noise model, the RMS values of the smoothed residual obtained by BDS-3 and BDS-2+BDS-3 PPP time transfer with the clock model is reduced by 65.17% and 74.42%; in addition, frequency stability can be increased up to 80%.

The digital twin earth fusioning BDS and GF

LIU Guangming, HU Yu, SHA Feng, XIE Guojun, CHENG Wei

2022, 47(4): 39-45. doi: 10.12265/j.gnss.2022033

[Abstract](470) [FullText HTML] (119) [PDF 2114KB](62)

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This paper expounds the origin, concept, construction and development of digital twin earth, especially the integration of BeiDou Satellite Naviation System (BDS) and GF, digital twin and digital earth. Based on common information infrastructure such as communication and computer, the construction of digital twin earth is divided into six steps: full-chain credible space-time, holographic precision mapping, real-time ubiquitous perception, multi-module data fusion, single spatio-temporal intelligence, and all-domain shared intelligence and governance. In view of the distributed characteristics of spatio-temporal big data from collection to application, the “BDS + block chain” technology is proposed to solve the trust problem in business collaboration. It is pointed out that GF realizes the holographic image between the virtual and real earth, and BDS delivers the space-time datum for products of GF, realizing the accurate mapping between the virtual and real earth. In addition, BDS and GF are also the main technologies to realize space-time situation awareness. In view of the challenges brought by massive spatio-temporal big data to data operation and fusion, it is pointed out that grid location code of BDS is a more effective data organization mode. This paper introduces artificial intelligence and simulation driven by spatio-temporal big data, which can provide optimal scheme for planning, design and decision making. This paper analyzes the problems of duplication construction and resource waste of single intelligence, and points out that digital twin earth is the temporal and spatial base for the cross-border integration of various heterogeneous single intelligence and the realization of all-domain shared intelligence and governance.

Performance analysis of BDS-2/BDS-3 carrier phase time transfer

YU Heli, LI Minglei, MA Guoyuan, YE Ziyu

2022, 47(4): 46-49. doi: 10.12265/j.gnss.2022007

[Abstract](330) [FullText HTML] (115) [PDF 2739KB](50)

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The mathematical model of carrier phase time transfer is given, and the performance of BeiDou-2/BeiDou-3 Navigation Satellite System (BDS-2/BDS-3) combined carrier phase time transfer is analyzed based on the measured data of the multi-GNSS experiment (MGEX). The results show that the addition of BDS-3 can increase the number of visible satellites and improve the spatial configuration of satellite distribution. Compared with only using the BDS-2 system, the time transfer accuracy of MRO1-CUSV and NNOR-CUSV can be improved from 0.11 ns and 0.10 ns to 0.07 ns and 0.08 ns, and the A-class uncertainty can be improved from 0.007 ns and 0.006 ns to 0.004 ns and 0.005 ns, respectively, in the BDS-2/BDS-3 combination scenario.

A hop correction-based node localization algorithm in things of network

TANG Yitao, DENG He

2022, 47(4): 50-54, 121. doi: 10.12265/j.gnss.2022043

[Abstract](219) [FullText HTML] (75) [PDF 2233KB](13)

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In view of the large localization error in the traditional DV-Hop algorithm in wireless sensor network, node localization based on lion swarm optimization (NLLSO) algorithm is proposed in this paper. In NLLSO algorithm, the minimum-hop estimation, average hop error correction and position process are optimized to reduce the localization error. Beacon packet is transmitted in multiple communication radii way, and accuracy of estimating minimum-hop count is improved. In addition, the weight is introduced to correct the average hop. Finally, lion swarm optimization algorithm is used to solve the position of the node. The simulation results show that positioning accuracy of NLLSO algorithm is significantly improved compared with traditional DV-Hop algorithm.

Stability analysis of GPS / BDS-3 system time offset

LIU Mingyue, TU Rui, HONG Ju, MIAO Yage, LI Fangxin

2022, 47(4): 55-63. doi: 10.12265/j.gnss.2022055

[Abstract](726) [FullText HTML] (112) [PDF 5833KB](47)

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The stability analysis of time offset between different satellite navigation systems is of great value in modeling prediction and application of time offset. Therefore, based on the data and products provided by the International GNSS Service Center (IGS), the stability analysis of system time offset between the GPS and BeiDou-3 Navigation Satellite System (BDS-3) from three aspects: different stations, different observations, and different time lengths. The results show: due to the different models of receivers, antennas and clocks, the time offset values extracted from different stations are different, but the stability is similar; The stability of the time offset result calculated based on the carrier phase observation is better than that of the pseudo range observation, the time offset result obtained by pseudo range has a frequency stability of the order of 10⁻¹² to 10⁻¹³ in 10 000 seconds, and the time difference obtained by phase has a frequency stability of 10⁻¹⁴ seconds. By comparing the time offset calculation results of single-day and multi-day data, it is obtained that the time difference stability of different durations is consistent.

Application of BDS in unmanned vehicle for land-based intelligent inspection

WU Qingyun, CHEN Lingxuan, LIU Xin, CAO Yu, XIE Pengyang

2022, 47(4): 64-72. doi: 10.12265/j.gnss.2022023

[Abstract](650) [FullText HTML] (102) [PDF 4570KB](32)

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The current transformation and upgrading of intelligent products, unmanned vehicles have been widely used in production and life practice and play a huge role. BeiDou Navigation Satellite System (BDS), as an independent localized advanced positioning and navigation system, will play an increasingly important role in the transformation and upgrading process of localized intelligent products. The intelligent inspection trolley needs to have autonomous navigation and positioning and environment awareness functions, and the positioning and navigation module and communication module play an important role. This paper designs a kind of intelligent inspection unmanned vehicle which is suitable for terrain scenes on land, adopts BDS satellite positioning system for positioning, senses the external environment based on multi-sensor information fusion, can realize the functions related to autonomous navigation and automatic obstacle avoidance, applies the unique short message system of BDS module to build the upper computer platform for information interaction transmission, and achieves good human-computer interaction effect. The reliability of the system is proved through the test, and it can carry out the autonomous cruise of the unmanned vehicle and the inspection path is basically consistent with the expected path. The BDS module as the core of the unmanned inspection vehicle equipped with various functional modules can create a series of related products for social production practice, which provides new ideas for the subsequent expansion of related technologies.

Accuracy analysis of generalized extension interpolation method in QZSS satellite clock bias interpolation

KOU Ruixiong, YANG Shuwen

2022, 47(4): 73-78. doi: 10.12265/j.gnss.2022029

[Abstract](309) [FullText HTML] (73) [PDF 2213KB](26)

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The satellite clock error data interpolation is an important link in process of high accuracy positioning data, which has directly impact on positioning accuracy. However, the common interpolation and fitting methods have different disadvantages. The generalized extension approximation method is tried to apply to the process of Quasi-Zenith Satellite System (QZSS) satellite clock error data in this paper. The principles of Lagrange interpolation, Chebyshev fitting and Generalized extension approximation method are firstly introduced, and the differences between sliding and non-sliding. Afterwards, QZSS clock error data is used to discuss the relationship between the parameters (groups) value of the above three methods and the interpolation results accuracy. Finally, when the three methods take their respectively optimal parameters (groups), the accuracy of QZSS satellite clock error is compared. The simulation results show, as long as reasonable parameter combination is selected, that the generalized extension interpolation is completely suitable to QZSS satellite clock error, and the interpolation accuracy of the generalized extension approximation method is significantly higher than other two methods.

The multifunctional BeiDou emergency position indicating radio beacon for smart fishing boat

ZHANG Zheng, LIU Zhaohui, CAO Shouqi

2022, 47(4): 79-83. doi: 10.12265/j.gnss.2022009

[Abstract](353) [FullText HTML] (95) [PDF 2860KB](27)

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A new type of multifunctional Emergency position indicating radio beacon (EPIRB) based on BeiDou positioning and short message communication technology was designed to overcome the shortcomings of poor positioning accuracy and single function of traditional EPIRB and meet the needs of informatization and intelligence of fishing boats. Firstly, the hardware of EPIRB were carried out. Secondly, the yaw angle simulation experiment of EPIRB in the extreme sea conditions and the message transmission and reception test were performed, and a short message sending mechanism based on the EPIRB attitude under different attitudes are proposed. Finally, experiments are conducted to verify the mechanism, and the experimental results show that the short message sending mechanism based on the EPIRB attitude can improve effectively the short message delivery rate, and the multifunctional BeiDou EPIRB designed in this paper has a good promotion prospect in the application of smart fishing boats.

Research and design of distributed architecture for high-precision location service platform

LI Yanhong, CHENG Fang, SHEN Pengli, LIU Dongliang, LI Xiaowan

2022, 47(4): 84-92. doi: 10.12265/j.gnss.2022008

[Abstract](302) [FullText HTML] (98) [PDF 2346KB](37)

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In view of the business features and off-site multi-centre development layout of the high-precision location service platform, this paper designs a distributed architecture solution for a high-precision location service platform to solve the problems of resource waste and business redundancy caused by the relative independence of the main centre and the sub-center, which cannot work together. The functional modules and platform architecture of the high-precision location service platform are designed in detail in the paper. The platform architecture is designed in a hierarchical way using a divide-and-conquer design philosophy, and the services are split and deployed according to the business design and business characteristics of the platform, solving the key problems in the process of system implementation, such as user acquisition service for distributed platform, real-time precise point positioning (RT-PPP) distributed processing and network Real-time Rinenatic (RTK) distributed processing. The design of a high performance and highly available distributed architecture solution compatible with the high-precision location service platform is finally achieved, providing an effective theoretical basis for the subsequent construction of the platform.

Atmospheric weighted mean temperature modeling for Japan

LUO Xiangtao, HUANG Liangke

2022, 47(4): 93-100. doi: 10.12265/j.gnss.2022035

[Abstract](689) [FullText HTML] (108) [PDF 3602KB](22)

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Due to the frequent occurrence of natural disasters, complex changes in water vapor characteristics, and sparse sounding stations in Japan, it restricts the acquisition of high-precision water vapor, and lacks a high-precision Tm model in this area. In view of this article adopts the 2009 to 2016 Global Geodetic Observing System (GGOS) weighted average temperature (T_m) with the ERA-Interim 2 m T_s grid data, a new T_m model (JQTm model) suitable for the Japanese region that takes into account the seasonal variation of the T_m residual and the daily cycle variation is established. In addition, using the data of 13 sounding stations and 110 GGOS Atmosphere T_m grids in Japan in 2017, the accuracy of the newly established JQTm model in this paper is evaluated in Japan. The study found that compared with the GGOS Atmosphere T_m grid data, the bias and root mean square error (RMSE) of the JQTm model are 0.15 K and 1.92 K, respectively. The RMSE is 41.16% (1.33 K) and 44.41% (1.53 K) higher than the GPT2w-1 and GPT2w-5 models, respectively. Compared with the sounding data, the bias and RMSE of the JQTm model are –0.66 K and 2.14 K, respectively. The RMSE is 28.43% (0.85 K) and 29.61% (0.90 K) higher than the Bevis model, GPT2w-1 model, and GPT2w-5 model, respectively. The JQTm model can provide high-precision T_m values for the Japanese region and provide an important basis for studying atmospheric water vapor and extreme weather in this region.

Performance analysis of auxiliary positioning algorithm under the condition of GEO Satellite

WU Peng, FENG Lu, HUANG Yajing, TONG Haibo

2022, 47(4): 101-105. doi: 10.12265/j.gnss.2022004

[Abstract](683) [FullText HTML] (140) [PDF 2108KB](26)

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In the process of satellite navigation and positioning, when the signal quality is poor, the auxiliary positioning algorithm can use more observed satellite data for redundant calculation, supplement the missing signal time and obtain the positioning results. The Beidou Satellite Navigation System (BDS) independently developed by China adopts a hybrid satellite constellation, including a class of Geostationary Earth Orbit (GEO) satellites, which has the advantages of 24 h visibility, high orbit, large coverage and strong signal power. This paper analyzes the auxiliary positioning algorithm and the performance difference of the algorithm when only GEO satellites can be received in special cases. The conclusion shows that without the assistance of prior information such as elevation, the direct use of five GEO satellites can also obtain a certain positioning accuracy guarantee.

Application of BeiDou-3 Navigation Satellite System in BeiDou ground-based augmentation system in Hubei province

LIN Xiaojing, XIANG Hao, LIANG Bin

2022, 47(4): 106-112. doi: 10.12265/j.gnss.2022027

[Abstract](335) [FullText HTML] (172) [PDF 2452KB](50)

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With the launching of the BeiDou-3 Navigation Satellite System (BDS-3), the BeiDou satellite ground-based augmentation system of Hubei province needs to be upgraded. It means the software and hardware of the entire network to achieve functional support for the BDS-3 satellite. This article introduces the content of this upgrade in detail: the upgrade of board hardware and firmware package of 72 true CORS R1 receivers, and providing support for the BDS-3 satellites; the software upgrade of the true NET platform. After the upgrade, the receiver regression test and system accuracy tests were carried out: the data quality analysis and double-difference quality analysis of the newly added frequency signal were carried out, and the number of satellites, altitude angle were analyzed for the original RINEX file; the performance of the receivers after upgrade are also evaluated. It shows that all indicators meet the requirements; the network real-time kinematic (RTK) positioning accuracy is better than 3 cm in horizontal and better than 5 cm in vertical; Differentinal Global Navigation Satellite System (DGNSS) positioning accuracy is better than 1m in horizontal and 2 m in vertical.

Research on attitude determination method based on GNSS antenna array

LIU Chunke, XU Gong, SHI Zhimin, ZHANG Yingqi, WANG Chenchen

2022, 47(4): 113-121. doi: 10.12265/j.gnss.2022025

[Abstract](348) [FullText HTML] (93) [PDF 4380KB](39)

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Aiming at the determination of the attitude of the moving carrier by the vehicle-mounted mobile measurement system, the attitude determination method of the vehicle-mounted Global Navigation Satellite System (GNSS) antenna array is studied, the attitude calculation formula of the direct method and the least square method is analyzed, and the GNSS is carried out. Antenna array vehicle experiment. In order to obtain the accuracy of the two attitude determination methods, the direct method and the least square method are used to calculate the attitude on the basis of different software positioning modes. The experimental and analysis results show that the accuracy of the four-antenna array least squares attitude determination is better than the three-antenna array direct method, and the reliability is higher; among all the combinations, the four-antenna array least squares attitude determination accuracy based on the moving-base positioning mode is the highest, its heading angle, pitch angle and roll angle accuracy can reach 0.066 0°, 0.168 4° and 0.267 8° respectively.

Short-term rainfall forecast by several typical machine learning algorithm

CHI Qin, ZHAO Xingwang, CHEN Jian

2022, 47(4): 122-128. doi: 10.12265/j.gnss.2022039

[Abstract](532) [FullText HTML] (107) [PDF 2987KB](59)

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According to the characteristic changes of precipitable water vapor and meteorological parameters (temperature (T), humidity (U), dew point temperature (T_d), surface pressure (P)) during the rainfall process, it is possible to establish a short-term rainfall forecast model based on machine learning algorithms. This paper uses the 3-hour zenith tropospheric delay and meteorological data of the bjfs station and wuh2 station in 2020 as examples to construct the prediction model of the four algorithms: random forest (RF), support vector machine (SVM), K-nearest neighbor (KNN), and naive bayes classifier (NBC), and introduces the rainfall events at each time as the new feature vector, adopts the segmentation method of 70% and 80% training sets respectively, takes the rainfall events as the model output, and the applicability of the model is evaluated by the accuracy, precision rate and false negative rate. After obtaining the accuracy is about 0.92, the precision rate is about 80%, and the false negative rate is about 20%, the data of 150—200 days in the time series are further used as samples to predict the rainfall of 200—250 days. The results indicate that The short-term rainfall forecast model based on machine learning can predict more than 80% of the rainfall events in the next 3 hours, and the false negative rate is below 20%, among which the SVM model has better comprehensive performance. Compared with the traditional threshold model, the accuracy rate is equivalent, and the false negative rate is decreased by about 50%.