全球定位系统

2019 Vol. 44, No. 2

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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](2451) [PDF 1536KB](1320)

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.

Correction of signal atmospheric propagation errors in quantum satellite positioning system

WU Wenshen, CONG Shuang, CHEN Ding

2019, 44(2): 13-20. doi: DOI:10.13442/j.gnss.1008-9268.2019.02.002

[Abstract](375) [PDF 1030KB](117)

Abstract:
In this paper, the propagation errors caused by the path delay of the signal passing through the ionosphere and the troposphere in the process of the entangled light signal in the quantum satellite positioning system are studied. According to the relationships between the ionospheric path delay, the entangled light frequency and the total free electron content of the ionosphere per unit area of the entangled light propagation path, three kinds of ionospheric path delay correction schemes are proposed, and the advantages and disadvantages of each scheme are analyzed. We also study five tropospheric path delay correction schemes based on the relationships between tropospheric path delay and meteorological parameters, and the relationship between meteorological parameters, latitude, altitude and annual product date. The advantages and disadvantages of each correction scheme are analyzed. The correction methods studied in this paper can increase further the accuracy quantum satellite positioning systems.

The method of refining real-time satellite clock offset reference

ZHANG Dong, SONG Weiwei, LOU Yidong, CHEN Liang

2019, 44(2): 21-28. doi: DOI:10.13442/j.gnss.1008-9268.2019.02.003

[Abstract](535) [PDF 913KB](113)

Abstract:
For timing based on PPP method, the high-accuracy time reference of satellite clock products is very important. Aiming at the problem that the time reference of real-time satellite clock products is not stable enough, this paper uses a set of IGS tracking stations with external input of atomic clock to establish a reference refinement method that takes into account the variation characteristics of atomic clocks. Firstly, we analyze the stability of the external atomic clock of the IGS tracking station based on Allan variance, and select highly stable atomic clocks to correct the time reference. On this basis, the Allan variance is used to calculate the noise parameters of each atomic clock and the corresponding weight ratio relationship. Finally, this paper establishes a stochastic model of time reference corrections and calculates the time reference after refinement. By comparing with the time reference implied by the IGS precision clock products, the STD of the corrected time reference is better than 0.1 ns in a single day, up to 93％ compared to before the correction. At the same time, the long-term stability at 10 000 s can reach the level of 10^-15, achieving an order of magnitude improvement.

The research and application of domestic tail positioning system

WANG Boyang, QIN Ke, SHAN Rui, WU Huisheng, WANG Zhenjie, CAO Fenghai

2019, 44(2): 29-37. doi: DOI:10.13442/j.gnss.1008-9268.2019.02.004

[Abstract](457) [PDF 912KB](83)

Abstract:
The composition and operation principle of the tail mark positioning system of GNSS independently developed by China University of Petroleum are described in detail.Then it introduces the application of self-developed tail positioning system in marine streamer operation, which including design of its core hardware and software and main workflow. Finally, the radio transmission distance and stability and positioning accuracy are tested by land-based simulation experiments. The test results show that the tail positioning system can continuously and stably transmit data and can achieve centimeter-level relative positioning accuracy, which can meet the requirements of navigation and positioning for offshore towing cable operation in actual production.

A method to high precision positioning based on airborne GNSS data

FU Yan

2019, 44(2): 38-45. doi: DOI:10.13442/j.gnss.1008-9268.2019.02.005

[Abstract](483) [PDF 970KB](109)

Abstract:
The ionosphere-weighted model with partial ambiguity resolution(PAR) strategy is proposed to improve the performance of airborne GNSS kinematic positioning: 1) The proposed model is flexible enough for short／long-range kinematic positioning through adaptive ionospheric and tropospheric estimation; 2) The virtual or pseudo ionosphere observation equations are introduced to enhance the model strength; 3) When full ambiguity resolution(AR) is unavailable, an alternative selection is provided to make the best use of integer constraint information. The proposed model is tested with real airborne GNSS kinematic positioning data. Both the AR efficiency and reliability is improved obviously with enhanced model strength and better float ambiguity solution, therefore kinematic positioning results show improvement in precision, reliability as well as the continuity of precision. Test results show that the wide-lane and narrowlane ambiguity fix rate is over 95％ and 80％ respectively within 2 minutes data.

Effect of non-uniform layering on 3D water vapor chromatography of GNSS

GAO Yao, YNAG Li, ZHU Enhui, ZHAO Shuang

2019, 44(2): 46-53. doi: DOI:10.13442/j.gnss.1008-9268.2019.02.006

[Abstract](343) [PDF 1058KB](76)

Abstract:
In view of the current low-precision accuracy of ground-based GNSS tomographic water vapor, this paper proposes a method for non-uniform stratification of the vertical direction of the mesh, which improves the accuracy of the regional tomographic results. Based on multisystem GNSS observation data, the water vapor distribution over the area of 111.5～115.5° east longitude and 33.6～35.6° north latitude in Henan Province is detected by tomography, and the influence of vertical stratification method on the chromatographic results is studied. The vertical stratification method adopts uniform and non-uniform stratification methods, and the results of water vapor density are very close to those of sounding inversion. By contrast, the non-uniform tomographic data analysis shows good data accuracy in correlation coefficient, root mean square error and mean deviation. The non-uniform stratification method can obtain better atmospheric water vapor inversion results.

BDS／GPS medium-long baseline quasi-centimeter RTK algorithm

GAO Chunwei, ZHAO Lijiang, LIU Haihong

2019, 44(2): 54-58. doi: DOI:10.13442/j.gnss.1008-9268.2019.02.007

[Abstract](585) [PDF 542KB](150)

Abstract:
Aiming at the problem of long baseline initialization time and unstable positioning results in conventional real-time dynamic (RTK) positioning technology, a BDS/GPS wide lane Kalman filter RTK positioning method based on partial ambiguity fixing strategy is proposed, which can make full use of the advantages of long observation wavelength and easy fixing ambiguity of wide lane, and avoid the influence of low altitude angle satellite on ambiguity resolution. At the same time, Kalman filter method with additional wide lane ambiguity parameters is used to calculate floating-point solution to fix the position of satellites higher than the cut-off altitude angle of ambiguity solution, and to calculate the mid-long baseline of 25-76 km with intense ionospheric activity. Through three groups of experiments, the results show that: BDS/GPS dual system locates wide lane ambiguity jointly. The degree fixing rate is close to 100%, the baseline ambiguity fixing rate of 76 km is 99.9%, and the positioning accuracy is centimeter or quasi-centimeter.

Comparison and analysis of direction finding methods of GNSS interference sources

CHAI Huisi, ZHANG Fengguo

2019, 44(2): 59-62. doi: DOI:10.13442/j.gnss.1008-9268.2019.02.008

[Abstract](677) [PDF 436KB](134)

Abstract:
With the increasing types and quantities of electronic equipment, the electromagnetic environment is becoming more and more complex. In order to ensure the normal operation of GNSS terminal equipment, it is necessary to find and eliminate the interference sources in time. Among them, the direction finding technology of interference sources is one of the core technologies. This paper makes a comparative analysis of the advantages and disadvantages of various interference direction finding methods, such as amplitude comparison method, phase comparison method and spatial spectrum method. It is of great significance to determine the reasonable and effective direction finding technology of interference sources and the development of related equipment.

Research on multipath error detection technology based on BDS three-frequency SNR

YUAN Yang, ZHANG Yun, YANG Shuhu, HAN Yanling, HONG Zhonghua, WANG Jing

2019, 44(2): 63-69. doi: DOI:10.13442/j.gnss.1008-9268.2019.02.009

[Abstract](509) [PDF 804KB](114)

Abstract:
Multipath error is the distance error of receiver and star caused by the destructive interference of indirect waves on direct waves. The multipath effect has timevarying characteristics, Which is difficult to be eliminated by model correction or differential techniques. In the case of multipath interference, the signaltonoise ratio fluctuates at different frequencies of the same satellite fluctuates. Therefore, this paper proposes a method to detect multipath by SNR, which establishes a statistic about the signal-to-noise ratio (experimental environment) and calculates the detection threshold of the open environment (low multipath environment), and compareds the statistical values of the experimental environment with the values of the low multipath environment detection threshold to detect the multipath error of the BDS satellite. The experimental results show that the proposed method can effectively detect the multipath error of the BDS satellite, and obtain better positioning effect by remove the satellites in a certain period of time based on the detection threshold and the change of position dilution of precision(PDOP).

GNSS time series prediction based on support vector machine

DENG Yongchun, XU Yue, XU Dandan, JIA Xue, TIAN Xiancai

2019, 44(2): 70-75. doi: DOI:10.13442/j.gnss.1008-9268.2019.02.010

[Abstract](293) [PDF 568KB](119)

Abstract:
In order to predict the global navigation satellite system (GNSS) time series, under the theoretical framework of deep learning, the traditional empirical risk minimization prediction model has low error, low generalization performance and large dependence on historical data. A time series prediction model is proposed based on support vector machine (SVM) with the principle of structural risk minimization. compared with the multi-layer BP neural network prediction model prediction, the results prove that the SVM prediction model has better time series prediction effect.

Analysis of the influence of tropospheric mapping function on GNSS inversion precipitable water vapor

HUANG Yiyu, WEI Guanjun, REN Rui

2019, 44(2): 76-83. doi: DOI:10.13442/j.gnss.1008-9268.2019.02.011

[Abstract](408) [PDF 813KB](131)

Abstract:
The tropospheric mapping function is an important model for transforming the zenith tropospheric delay into the total delay on the signal propagation path. Choosing an appropriate mapping function is of great significance for retrieving the accuracy of atmospheric precipitation water vapor(PWV). In this paper, the influence of tropospheric mapping function on the inversion of atmospheric PWV accuracy is studied. Select three kinds of mapping functions, VMF1, GMF and NMF, and use GAMIT software to compare the three mapping functions in different seasons and different altitudes. Retrieving the accuracy impact of atmospheric PWV. The results show that the inversion accuracy of the GMF function model with 10° elevation angle as the solution cutoff height angle is the best when the atmospheric precipitation is inverted, Which provides a reference for further improving the real-time accuracy of GNSS atmospheric water vapor inversion.

Establishment of GPS velocity field models of Fujian province by using multi-surface function fitting and Euler vector methods

DU Zhongjin

2019, 44(2): 84-88. doi: DOI:10.13442/j.gnss.1008-9268.2019.02.012

[Abstract](321) [PDF 610KB](77)

Abstract:
By processing data of Fujian continuously operating reference station (FJCORS) from 2013 to 2015, the observed velocity of GPS station is obtained. On this basis, the GPS velocity field models of Fujian province and the surrounding areas are established by using multi-surface function fitting method and Euler vector method respectively. The precision of velocity obtained by using multi-surface function fitting is 1.06 mm／a for north-south component and 2.00 mm／a for east-west component, while the precision of velocity obtained by using Euler vector method is 1.36 mm／a for north-south component and 1.22 mm／a for east-west component. Meanwhile, the differences between the modeled velocity value and the observed velocity value obtained by using the two methods for the check stations are mainly within ±2.28 mm／a. In the terrestrial region of Fujian province, the velocity field obtained by the two methods has highly good consistency, the velocity values are about 35 mm／a, and the motion direction is SE-E.

Coordinate time series analysis of Hong Kong CORS station

CHEN Chen, WEI Guanjun, GAO Zhiyu, KOU Ruixiong

2019, 44(2): 89-97. doi: DOI:10.13442/j.gnss.1008-9268.2019.02.013

[Abstract](630) [PDF 926KB](152)

Abstract:
According to the difference between the periodic characteristics and the noise characteristics of the coordinate time series of CORS stations in different regions, the power spectrum analysis method and the maximum likelihood method are used to analyze the coordinate time series of the Hong Kong satellite reference station network (SatRef). The research results show that there are obvious annual period items and half-year period items on the three coordinate components of the reference station. There are diversified features of the noise characteristics on the coordinate components of each reference station. White noise plus flicker noise is the main noise model. The practice of considering only white noise and neglecting colored noise can greatly underestimate the uncertainty of parameter estimation. According to the optimal noise model, the velocity field of the SatRef station has a trend of moving toward the southeast in the horizontal direction, which is basically consistent with the motion of the South China block.

Application analysis of BDS precise point positioning in bridge deformation monitoring

LIU Mingliang, DING Keliang, LIU Yajie, YU Longhao, BAO Dongdong

2019, 44(2): 98-102. doi: DOI:10.13442/j.gnss.1008-9268.2019.02.014

[Abstract](590) [PDF 573KB](136)

Abstract:
Bridge deformation monitoring is an important part of bridge health assessment and repair. Based on BDS's precise single-point positioning technology, this paper conducts PPP static and dynamic processing on high-frequency BDS／GPS data collected in real time, and uses relative static positioning results as a reference to analyze the precision of BDS's precision single-point positioning in a complex bridge environment. Compare BDS dynamic PPP results with GPS, the research results show that the BDS static precision single point positioning accuracy and the BDS dynamic PPP positioning accuracy can reach centimeter level around 1 h continuous deformation monitoring time. We can monitor the deformation of large vehicles passing through the bridge, which is basically consistent with the GPS monitoring deformation trend. With the continuous improvement of BDS's positioning accuracy, BDS's precise singlepoint positioning can become a new method for bridge deformation monitoring.

Accuracy analysis of data process of C-Grade GPS network with precise ephemeris and broadcast ephemeris

2019, 44(2): 103-109. doi: DOI:10.13442/j.gnss.1008-9268.2019.02.015

[Abstract](499) [PDF 664KB](154)

Abstract:
This paper uses Trimble Business Center 2.8 data processing software to perform C-Grade GPS control network baseline solution and network adjustment with precision ephemeris and broadcast ephemeris. The GAMIT software is used to load precise ephemeris data for baseline solution, and the adjustment calculation is performed with the COSAGPS software. According to the data obtained with above methods, the influence of different ephemeris solutions on the C-Grade GPS baseline solution and the network adjustment results are analyzed. The results yield that the TBC software can respectively perform C-Grade GPS analysis with both ephemeris, but the accuracy of the baseline solution with the precise ephemeris is slightly high. Thus the appropriate data process strategy should be employed according to the actual situation in fieldwork.

Application of BDS in communication of floating self-powered breakwater

WANG Shiming, WANG Jiazhi, LI Zeyu, LI Miaomiao

2019, 44(2): 110-115. doi: DOI:10.13442/j.gnss.1008-9268.2019.02.016

[Abstract](299) [PDF 639KB](81)

Abstract:
In order to control the working state of floating self-powered breakwater and the collected water quality information, a communication system based on BDS is designed. This system aims to improve the protection of aquaculture net cage and monitoring the water quality around the cage.This communication system uses the RDSS mode of BDS, adopts customized data communication protocol, locates the breakwater position in real time, then transmits the information collected by various sensors and user instructions. Combining with shore-based server or workstation, the real-time and all-weather monitoring of the breakwater is realized, and the controllability of the floating self-powered breakwater is improved.

Construction and implementation of Guangxi modern surveying and mapping datum management and comprehensive service platform

YANG Yifei

2019, 44(2): 116-121,126. doi: DOI:10.13442/j.gnss.1008-9268.2019.02.017

[Abstract](341) [PDF 746KB](92)

Abstract:
In view of the deficiencies of Guangxi surveying and mapping datum management, such as decentralized operation and peacekeeping services, mechanical and offline management services, a modern surveying and mapping datum management and integrated service platform in Guangxi is constructed based on internet, satellite navigation and positioning technology and geographic information technology. Comprehensive supervision, intelligent operation and maintenance management and differential service (C/S) and online integrated service (B/S) are carried out for modern surveying and mapping datum in Guangxi. Through the grid-connected management of satellite navigation and positioning reference station, the ability of government service and safety supervision is enhanced; the intelligent operation and maintenance is realized by using video surveillance, electronic operation and peacekeeping entrustment control system; the convenience and efficiency of user application and use services are enhanced by using full-line application, GNSS automation solution and multi-level multi-satellite positioning service, and the construction of the platform obviously improves the service, quality and operation level.

Application of wavelet threshold de-noising in GPS pseudo-distance single point positioning

WANG Mengying, FENG Mingyang, YU Jie

2019, 44(2): 122-126. doi: DOI:10.13442/j.gnss.1008-9268.2019.02.018

[Abstract](380) [PDF 587KB](83)

Abstract:
In single point positioning,the accidental errors such as multipath effect and receiver noise have a great influence on the accuracy of positioning, and it is difficult to select a fixed model to weaken it. In view of the above problems, analyzes the principle of wavelet analysis from the signal structure and error source of GPS, and uses the discrete orthogonal wavelet db3 to denoise the GPS observation C1.The experiment shows after the observed values are processed using the method described above, the accuracy of positioning can be improved by 31.93％ in the period when the quality of the observed value is bad, and the positioning accuracy can be increased by 16.02％ in the period when the quality of the observed value is good.