全球定位系统

2020 Vol. 45, No. 4

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Maximum correntropy Kalman filter for GNSS／INS tightly-coupled integration

LI Song, TANG Xiaomei, SUN Pengyue, ZHANG Ke, WANG Feixue

2020, 45(4): 1-8. doi: 10.13442/j.gnss.1008-9268.2020.04.001

[Abstract](776) [PDF 846KB](169)

Abstract:
In real application, the measurement noise is easily affected by gross errors and becomes nonGaussian distribution, resulting in the performance of the traditional Kalman filter (KF) being degraded significantly. In order to deal with this problem, the maximum correntropy Kalman filter (MCKF) is proposed based on the maximum correntropy criterion (MCC) and M-estimation. Compared with KF, the proposed filter can assign less weight to the abnormal measurements to reduce its influence on the state estimation, and compared with the Huber-based Kalman filter (HKF), it can make more effective use of measurement information, thereby the proposed filter is more robust. The tightly coupled GNSS／INS (global navigation satellite system／inertial navigation system) carmounted experiments were carried out to verify the performance of the proposed filter. The results show that the KF and HKF achieve bad estimation accuracy due to the poor quality of the original measurements of the GNSS such as the pseudorange and pseudorange rate. And the proposed MCKF can effectively suppress the influence of abnormal measurements, resulting in faster convergence and higher estimation accuracy than existing filters.

FFT algorithm design of GNSS multimode eceiver acquisition module

YUAN Jin

2020, 45(4): 9-13. doi: 10.13442/j.gnss.1008-9268.2020.04.002

[Abstract](443) [PDF 565KB](56)

Abstract:
With the development of GNSS and Internet of things technology, multi mode receiver has been used more and more widely. As the first step of signal processing in the receiver, signal acquisition ability directly affects the overall performance of the receiver. In this paper, an optimization method is proposed to solve the problems such as poor FFT algorithm compatibility, long operation time and large resource occupation encountered in the design of the capture module of multi mode receiver. The method is designed by adding intercept operation, module reuse and pipeline structure to solve the above problems. The simulation analysis and hardware implementation show that this method has obvious improvement in resource occupation, operation time and compatibility.

Research on time reference determination and phase calibration method of high precision measurement system

GUO Yu, CHEN Lei, LI Jingyuan, HUANG Yangbo, OU Gang

2020, 45(4): 14-20. doi: 10.13442/j.gnss.1008-9268.2020.04.003

[Abstract](971) [PDF 846KB](110)

Abstract:
Aiming at the requirements of time reference determination and phase calibration of high-precision measurement systems, a high-precision phase determination and calibration method of time reference is proposed to solve the problem of low calibration accuracy in the system. This method uses FPGA delay lines to perform time reference Delay control combined with phase jump detection technology. First, accurately determine the interval where the phase transition occurs when the time reference is sampled by the system clock; second, accurately measure the delay value required to stabilize the time reference, and finally perform the time reference internal delay, and system synchronization of the delayed time reference. The proposed method has the characteristics of high calibration accuracy and low complexity. A simulation verification platform was built and the functional verification of the proposed method was performed in conjunction with a computer. The method has been applied to highprecision measurement systems.

Research on GNSS time offset monitoring based on GLONASS IFBs

KONG Sijia, XIE Weihua

2020, 45(4): 21-28. doi: 10.13442/j.gnss.1008-9268.2020.04.004

[Abstract](970) [PDF 878KB](122)

Abstract:
To enhance the compatibility and interoperability among GNSSs, it is necessary to monitor system time offset among GNSSs. At present, the main method of GNSS time offset monitoring is Signal-in-Space Reception method. Because of the FDMA technique, GLONASS satellites have different signal frequencies. It leads to IFBs for both pseudorange and carrier phase observations. The GLONASS IFBs will influence the GNSS-GLONASS system time offset monitoring. To reduce the impact of GLONASS IFBs, this paper proposes a method of GNSS time offset monitoring with GLONASS IFBs estimated. The simulation result indicates the accuracy of GPS-GLONASS time offset can be improved by more than 90％ on average.

Impact of IGS precise ephemeris on the precision of level C GPS network solution

ZHANG Pan, LI Yalun, FENG Yin

2020, 45(4): 29-35. doi: 10.13442/j.gnss.1008-9268.2020.04.005

[Abstract](356) [PDF 760KB](33)

Abstract:
Taking common commercial software TBC and HGO as carriers, load precision and broadcast ephemeris are respectively resolved. Fifty-seven baselines are randomly selected for analysis in this paper, and the adjustment results are compared with the acknowledged data. It shows that for GPS networks of grade C, the results of loading a broadcast ephemeris with the software are reliable.

Analysis on GNSS receive performance and observation data quality in substation environment

E Shenglong, ZHOU Gang, TAN Liqing, LUO Yingting, XU Hailin

2020, 45(4): 36-41. doi: 10.13442/j.gnss.1008-9268.2020.04.006

[Abstract](321) [PDF 651KB](46)

Abstract:
In order to study the impact of strong electromagnetic environment of the substation on performance of the GNSS receiver and quality of observation data,GNSS receivers were arranged on the roof of main control building of the 500 kV, 220 kV and 110 kV substation respectively to observe continuously for 24 hours. The impact of substation on performance of the GNSS receiver and the quality of the observation data is comprehensively evaluated through internal noise of the receiver,data integrity rate, signal-to-noise ratio, and multipath effects. The experimental results show that the GNSS receiver can work normally under strong electromagnetic environment of the substation, and the substation does’t have significant impact on quality of observation data.The quality of observation data meets the corresponding standards.

Analysis of the composition and deployment methods of SBAS ground monitoring stations

QU Pengcheng, LIU Xiang, JIN Biao, CHEN Shanshan, XIA Chuanru

2020, 45(4): 42-48. doi: 10.13442/j.gnss.1008-9268.2020.04.007

[Abstract](391) [PDF 877KB](71)

Abstract:
The satellite Based Augmentation System (SBAS) can enhance the performance of GNSS positioning and integrity service to meet the needs of civil aviation users. The ground monitoring station is an important part of SBAS, and its composition, layout, and data quality have an important impact on the service performance of SBAS. Therefore, based on the actual observation data from the WAAS and EGNOS, the composition and distribution, the antenna distribution, the data quality, and the multipath correlation of the ground monitoring station are analyzed in detail in this article. And a general method for the composition and deployment of the SBAS ground monitoring station is summarized, which provides a reference for the implementation of SBAS monitoring station construction.

Design and implementation of navigation interference source detection and positioning system based on unmanned aerial vehicle

DOU Xiaojing, LIU Jing, LYU Xin

2020, 45(4): 49-57. doi: 10.13442/j.gnss.1008-9268.2020.04.008

[Abstract](331) [PDF 1050KB](74)

Abstract:
Global Navigation Satellite System is widely used because of its wide coverage and low cost. However, due to the use of MEO,IGSO and GEO satellites, the signal landing power is low and susceptible to interference. Therefore, to ensure the normal use of GNSS, it is necessary to carry out research on the detection and positioning of navigation interference sources. Aiming at the defects of low positioning accuracy, weak maneuverability, long positioning time, and high dependence on the environment, this paper proposes a navigation interference source detection and positioning system based on UAV. The design and implementation method is to realize the detection and positioning the navigation interference sources by carrying direction finding loads on unmanned aerial vehicles. The system has the advantages of long working distance, large coverage area and strong maneuverability.

Study of a grid GNSS weak interference positioning method

LIU Rui, CHEN Qidong, ZHEN Weimin

2020, 45(4): 58-62. doi: 10.13442/j.gnss.1008-9268.2020.04.009

[Abstract](383) [PDF 513KB](68)

Abstract:
This paper introduces the system composition of grid GNSS weak interference source location. Aiming at the problem that the existing methods have poor adaptability to low signal-to-noise ratio (SNR), this paper proposes a grid GNSS weak interference source localization method based on Mean Function of Difference Square based on Separation of signal and noise (MFDSS). The method uses MFDSS method to realize time difference estimation, and Chan hyperbolic positioning algorithm is used to calculate the location of interference source. This paper compares and simulates the positioning effect of this method and the commonly used grid positioning method. The results show that the method has superior performance in the GNSS weak interference source localization scene.

Robust perception algorithm for indoor and outdoor scenes based on signal of opportunity

YAN Song, WU Fei, ZHU Hai, LU Wenxia, HU Rui, NIE Dawei

2020, 45(4): 63-71. doi: 10.13442/j.gnss.1008-9268.2020.04.010

[Abstract](233) [PDF 1078KB](32)

Abstract:
Considering that the development of navigation application service requirements for the combination of indoor and outdoor scenes and the problems of low recognition stability and the low recognition accuracy of existing indoor and outdoor scenes perception methods, this paper proposes a robust sensing algorithm for indoor and outdoor scenes based on signal of opportunity. The signal of opportunity is used to reduce the single signal recognition error. In order to improve the classification accuracy of the traditional AdaBoost algorithm for imbalanced data sets, the Probabilistic Neural Network(PNN) is used as the training weak classifier, and the entropy weight method is introduced to modify the weight of the weak classifier generated by iteration to improve the classification accuracy of the strong classifier. Experimental verification in real scenarios shows that the algorithm in this paper performs best in indoor and outdoor scene perception using signal of opportunity: WiFi signal, available GNSS stars, and light intensity in indoor and outdoor environments. For scenes switching in different angle directions, the recognition accuracy of 98％ can be achieved with a false alarm rate of only 1.7％, which verifies the accuracy and robustness of the algorithm proposed in this paper.

High precision outdoor positioning to determine the indoor initial point

XI Chao, CAI Jing, YANG Bo, SHEN Wenbo, CAI Chenglin

2020, 45(4): 72-75. doi: 10.13442/j.gnss.1008-9268.2020.04.011

[Abstract](275) [PDF 485KB](62)

Abstract:
Indoor and outdoor seamless positioning is divided into two independent parts: indoor positioning and outdoor positioning. Indoor positioning usually selects (0,0,0) as the coordinate of the initial geomagnetic point, but this coordinate will be changed with the change of the experimenter or the change of the experimental site, which is not universal. Although GNSS cannot be positioned indoors, the geocentric fixed coordinates located outdoors with GNSS are unique and do not change. In this paper, the geocentric solid coordinate point of GNSS seamless positioning transition point indoors and outdoors is selected as the initial point. Geocentric solid is also used in the indoor positioning coordinate system, which can effectively solve the coordinate compatibility problem of seamless positioning indoors and outdoors and has a broader role.

Research on multi-mode integrated communication system technology about an ocean floating platform based on intelligent communication gateway

XU Zhiqiang

2020, 45(4): 76-82. doi: 10.13442/j.gnss.1008-9268.2020.04.000

[Abstract](325) [PDF 875KB](39)

Abstract:
This paper proposed a multimode integrated wireless communication system for the marine unmanned platforms. The system utilized an intelligent communication gateway technique to effectively integrate various marine communication methods, including satellite communication, Beidou short message communication system, mesh, Lora, ultra-short wave communication, WiFi, underwater acoustic communication, optical communication, electromagnetic coupling communication and etc. Moreover, in order to realize the capability of a reliable two-way communication between the marine information elements and the shore based data center, which can work continuously under all kinds of climate conditions, a real-time, reliable and seamless two-way communication link is built between the shore based data center, the mobile deployed surface mother ship, the mobile deployed marine buoy platform, and the mobile deployed underwater motion carrier.

Two GNSS-R specular reflection point search algorithms

LIU Yuanhua, SUN Yi, NIU Xinliang

2020, 45(4): 83-88. doi: 10.13442/j.gnss.1008-9268.2020.04.013

[Abstract](335) [PDF 547KB](54)

Abstract:
Global navigation satellite reflection system (GNSS-R) is of great significance for the extraction and research of accurate information of ocean surface topography. In this paper, two specular reflection point search algorithms are proposed for the accuracy of specular point search. Firstly, based on the analysis of the basic reflection relation, a search algorithm based on Fibonacci method is proposed, and its superiority over the golden section method is proved from the perspective of number theory. Secondly, a method based on extreme derivative is proposed to establish the distance and function of the variable K, which omits the iterative process in the traditional method. Finally, GNSS satellite and receiver coordinates are generated by navigation simulator, and MATLAB is used for simulation. The simulation results show that the Fibonacci method is better than the Golden Section, and the extreme derivative method can calculate the position information of the specular reflection point, and the traditional iterative step is abandoned.

Discussion on key technology of large scale image free control for UAV

WANG Yongju, GONG Ke, DONG Zhenglan

2020, 45(4): 89-94. doi: 10.13442/j.gnss.1008-9268.2020.04.014

[Abstract](227) [PDF 794KB](36)

Abstract:
Aiming at the problem that the time exposure error of image acquisition is not uniform due to the unstable flight speed of UAV photography, a large-scale image free control method for UAV is proposed. First of all, this paper discusses the analysis of the camera lens distortion error model and the problem that the exposure of UAV is not synchronized due to the exposure delay. Then, the exposure delay model is introduced into the traditional GPS auxiliary beam method adjustment model, and a GPS auxiliary beam method adjustment method with the exposure delay is proposed. Finally, the effectiveness of this method is verified by an engineering example. The experimental results show that this method can be used in the UAV when the control point is involved, thus it can meet the accuracy requirement of 1∶500 large scale mapping.

A piecewise Hermite interpolation method for BDS-3 receiver

AN Yunfei

2020, 45(4): 95-100. doi: 10.13442/j.gnss.1008-9268.2020.04.015

[Abstract](289) [PDF 617KB](33)

Abstract:
In order to speed up the time-consuming computation of satellite position and velocity in the process of satellite navigation and positioning, a piecewise Hermite interpolation method for BDS-3 receiver is proposed. This method first derives the velocity and acceleration formulas of BDS-3 satellite, and then constructs a piecewise cubic Hermite interpolation polynomial of satellite position and velocity, respectively. The proposed method improves the satellite velocity interpolation accuracy without increasing the computational complexity, and the formula is simple and easy to program. The selfdeveloped receiver of our company was used to verify the accuracy and efficiency of the proposed method, compared with Hermite interpolation,piecewise cubic Hermite interpolation and piecewise quintic Hermite interpolation.

Joint acquisition strategy for BDS B1C signal

WU Tao, TANG Xiaomei, MA Chunjiang, WU Jian, SUN Guangfu

2020, 45(4): 101-108. doi: 10.13442/j.gnss.1008-9268.2020.04.016

[Abstract](340) [PDF 933KB](61)

Abstract:
At present, the research on the acquisition of new signals with pilot channel mainly focused on the design of joint acquisition algorithms, which can increase power utilization so as to improve receiving performance. These algorithms can be divided into two categories: equal length and unequal length coherent integration joint algorithms. For BDS B1C signal, this paper analyzed the weighting problem of three equal length coherent integral joint algorithms, and the relationship between coherent and differential joint algorithm is explained. The theoretical and simulation results show that the coherent joint algorithm has better performance. Furthermore, the design scheme of acquisition parameters is proposed based on the theory of optimal coherent integration time. The performance of the equal and unequal length coherent integration algorithm is compared under different conditions, and the optimal strategy for acquiring B1C signal is given.

The optimal configuration and simulation of BDS GEO satellites precise orbit determination

GAO Yang, ZHANG Qiang, ZHANG Longping

2020, 45(4): 109-113. doi: 10.13442/j.gnss.1008-9268.2020.04.017

[Abstract](275) [PDF 1029KB](37)

Abstract:
The BDS-3 GEO satellites provide a number of unique services, but the accuracy of its precise orbit determination is poor. In addition to high altitude and constant position, the monitoring stations configuration is also an important factor of GEO satellites orbit determination. Firstly, the basic principle of orbit determination is introduced and the observation equation is linearized in this paper. Secondly, The GDOP value is parameterized by using orthogonal trigonometric functions and expressed in the configuration of the monitoring stations. Thirdly, the relationship between stations configuration and the accuracy of precise orbit determination is analyzed according to nested cones. Finally, the simulation experiments are carried out, and a kind of optimal solution is concluded.

Accuracy analysis of BDS-3 pseudo-range single-point positioning in the Arctic

CHEN Yonggui, ZHU Yuxing

2020, 45(4): 114-118. doi: 10.13442/j.gnss.1008-9268.2020.04.018

[Abstract](337) [PDF 537KB](57)

Abstract:
Aiming at the positioning performance of BDS-3 in the Arctic region, based on the METG station and SOD3 station, this paper analyzes the visible satellite number, PDOP value, single-frequency and dual-frequency pseudorange，and single-point positioning accuracy of the BDS-3 in the Arctic region. After research, it was found that the visible number of the BDS-3 satellites and the PDOP value in the Arctic region are consistent with that of the GPS satellites. The pseudo-range accuracy of the single point positioning accuracy of the B1I frequency and the B3I frequency is slightly worse than that L1 frequency of the GPS satellite. The accuracy of the pseudo-range single-point positioning of the B1I／B3I frequency combination is lower than that of pseudo-range single-point positioning of any single-frequency, and is slightly worse than that L1／L2 frequency combination of the GPS satellite.