全球定位系统

2019 Vol. 44, No. 3

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CNN and RNN-based pixel-wise video object tracking algorithm

CUI Jialiang, FENG Zhaohui, LI Qin, ZHAO Hongying

2019, 44(3): 1-6. doi: DOI:10.13442/j.gnss.1008-9268.2019.03.001

[Abstract](473) [PDF 701KB](125)

Abstract:
Video object tracking is a research hotpot of computer vision, but the object tracking algorithm is one of weaknesses in localization with video. In this paper, we introduced the pixel-wise video object tracking problem. We proposed a pixel-wise video object tracking algorithm based on convolution and recurrent neural network of deep learning technology and the latest research results in image segmentation to solve the problem. By designed and conducted an experiment and evaluation on a public dataset, the algorithm shows abilities on obtaining the boundary of objects in videos.

Co-frequency interference suppression of airborne VDB receiver based on blind signal separation

NI Yude, LI Xuguang

2019, 44(3): 7-13. doi: DOI:10.13442/j.gnss.1008-9268.2019.03.002

[Abstract](343) [PDF 754KB](72)

Abstract:
Aiming at the problem of co-frequency interference of ground-based augmentation systems (GBAS) airborne VHF Data Broadcasting (VDB) receiver in the process of precise approach and landing for civil aviation aircraft using GBAS, a blind signal separation algorithm is proposed to separate the desired signal from the same frequency interference signal received by VDB receiver. The desired signal is obtained by identifying the airport ID in the decoded data, so as to suppress the same frequency interference signal. Based on fast independent component analysis (Fast ICA) algorithm, natural gradient algorithm and equivariant adaptive separation via independence (EASI) algorithm, the mechanism of separating mixed signals received by VDB receivers and the realization of co-channel interference suppression are analyzed and simulated. The simulation results show that the three algorithms can effectively separate the desired signal from the same frequency interference signal, and then suppress the same frequency interference. It is concluded that fast ICA algorithm is more suitable for the same-frequency interference suppression of VDB signals by comparing the convergence speed, crosstalk error and bit error rate of the three algorithms.

The technique of dual-loop tracking of QMBOC signal

REN Yufei, LU Xiaochun, FENG Rui

2019, 44(3): 14-22. doi: DOI:10.13442/j.gnss.1008-9268.2019.03.003

[Abstract](416) [PDF 968KB](102)

Abstract:
Aiming at the problem of multi-zero ambiguity elimination in quadrature multiplexed binary offset carrier signal tracking, the common new dual-loop tracking method is theoretically analyzed under the analysis of the common methods of ambiguity elimination, and the dual-loop tracking of the binary offset carrier signal is used to track and simulate QMBOC signal, meanwhile it is compared with the sub-carrier joint loop tracking simulation. The simulation results show that the BOC(1,1) dual-loop tracking error approaches 0 under the environment of the carrier-to-noise ratio higher than 24dB·Hz, which is less than tracking error under the joint tracking method, which is achieving better processing results.

Influence of geomagnetic storm on the two-dimensional distribution of TEC

YU Houfang, GUO Wenxing, ZHANG Yuqiang, FENG Jian, ZHEN Weimin

2019, 44(3): 23-31. doi: DOI:10.13442/j.gnss.1008-9268.2019.03.004

[Abstract](405) [PDF 1030KB](91)

Abstract:
The Ionospheric Total Electron Content (TEC) is one of the most important parameters in ionospheric sounding. A large number of vertical TEC data can be obtained by using the hundreds of GPS stations which are distributed around the world. In this paper, a reconstruction method of high precision TEC is proposed， and the Kriging interpolation method is used to interpolate the vertical TEC data in order to obtain the high resolution two-dimensional distribution of TEC. The accuracy and effectiveness of the proposed method are compared with the measured data. Based on the two-dimensional distribution, the changes of regional TEC value with time and latitude are analyzed, particularly in the influence of geomagnetic storms on the TEC value. and The differences and explanations of TEC changes in different latitudes are also given. The related research results can provide the method support for the establishment of regional high resolution ionospheric monitoring system.

Non-difference FCB estimation and the application in fixed fuzziness of PPP

SONG Baofeng, HAO Jinming, SHI Yishuai, JIAO Bo

2019, 44(3): 32-37. doi: DOI:10.13442/j.gnss.1008-9268.2019.03.005

[Abstract](453) [PDF 723KB](133)

Abstract:
The ambiguity fixing technology can significantly improve the accuracy and convergence speed of precise point positioning (PPP), which is a research hotspot in the field of satellite navigation and positioning at home and abroad. In this paper, the receiver and satellite FCB are separated by the least square method, and the integer characteristic of non-difference ambiguity is restored. The obtained satellite-end FCB can be provided to the user to realize precise single-point positioning with fixed non-difference ambiguity. The experiment of zero-difference FCB estimation is implemented with the observations from IGS tracking stations worldwide. The result shows that wide-lane FCBs are stable and its variations in a week are within 0.1 cycle, but the variation of narrow-lane FCBs in a day is large. The estimated FCBs are used for the PPP experiment with ambiguity resolution. The position accuracy in E, N and U directions are 0.7 cm, 0.8 cm and 2.1 cm respectively. Compared with the floating-point PPP, the position accuracy in E, N and U directions are increased by 68％, 51％ and 37％ respectively, which verifies the performance of estimated FCBs for the ambiguity fixed PPP.

Analysis of global ionospheric electron content changes during magnetic storm

CHEN Zhihua, SHI Kun, XU Jisong

2019, 44(3): 38-48. doi: DOI:10.13442/j.gnss.1008-9268.2019.03.006

[Abstract](341) [PDF 1844KB](115)

Abstract:
The ionospheric electron content (TEC) is greatly affected by solar activity. When the magnetic storm occurs, the TEC changes vary widely in the world. It is very important to study the variation of TEC perturbation in this period for the study of the ionosphere.According to the inverse relationship between the ionospheric delay of the GNSS signal and the square of the signal frequency, the total electron content TEC change on the signal propagation path can be obtained. Without considering the absolute value of the TEC, the high-precision relative TEC can be obtained by using the carrier phase L4 combination, which is used to detect ionospheric disturbances. In this paper, the disturbance characteristics of the giant magnetospheric storm in March 2015 are studied by using GNSS TEC data including Beidou system and f_oF2 data of ionospheric altimeter in China, and its possible physical mechanism is discussed.

Comparative study on wavelet analysis and empirical mode decomposition for BDS multipath error reduction

TAO Yuan, DNEG Yongchun, HU Haojie, GAO Xiang

2019, 44(3): 49-55. doi: DOI:10.13442/j.gnss.1008-9268.2019.03.007

[Abstract](398) [PDF 758KB](102)

Abstract:
When using BDS for high-precision deformation monitoring, the multipath effect generated by BDS signal is a non-negligible error source that affects the accuracy and reliability of deformation monitoring data. The BDS has three different orbiting satellites, and the resulting multipath error is more complicated. Multipath error based on coordinate domain uses wavelet analysis (Wavelet) and empirical mode decomposition (EMD) for original sequence denoising, and advanced sidereal filter (ASF) for denoising sequence for multipath error culling. The two methods improved the baseline accuracy by 38.6% and 40.8% in E direction, 59.1% and 61.0% in N direction, 57.8% and 57.9% in U direction, respectively. The empirical mode decomposition improved the smoothness of the coordinate sequence and the baseline accuracy better.

Elevation compensation surface optimization based on least square and exhaustion search method

DENG Biao, LI Peng, LI Deliang, WANG Yanxia

2019, 44(3): 56-61. doi: DOI:10.13442/j.gnss.1008-9268.2019.03.008

[Abstract](320) [PDF 1883KB](95)

Abstract:
Aiming at the problem of Gaussian projection length deformation, based on the mechanism of deformation, the least square method is used to deduce the optimal compensation projection surface and the central meridian, and the exhaustive search method is used to quickly determine the optimal projection parameters. The example shows that this method has obvious effect on restricting the deformation of Gauss projection.

Abnormal change of GNSS ZTD before and after earthquake based on wavelet transform

WANG Yong, LOU Zesheng, LIU Yanping, WANG Xuan

2019, 44(3): 62-68. doi: DOI:10.13442/j.gnss.1008-9268.2019.03.009

[Abstract](468) [PDF 713KB](109)

Abstract:
The characteristics analysis of precipitable water vapor (PWV) change before and after earthquakes can provide reference for earthquake prediction and early warning of secondary disasters after earthquakes. In this paper, the abnormal changes of GNSS ZTD (PWV) before and after earthquakes are studied with the method of wavelet transform. By combining ZTD, seismic and precipitation data, the characteristics of water vapor change before and after earthquakes are analyzed. The ZTD data is decomposed and reconstructed by wavelet transform, and the abnormal changes of GNSS ZTD before and after earthquakes is analyzed. It is found that there is a sudden change of water vapor before and after earthquakes, and the ZTD after wavelet transform can clearly show the relationship between the characteristics of water vapor change and earthquakes and the change of water vapor cycle after earthquakes.

BDS dynamics based on Kalman filtering research on pseudorange differential positioning algorithm

SUN Maojun, LI Xia, ZHAO Lijiang

2019, 44(3): 69-73. doi: DOI:10.13442/j.gnss.1008-9268.2019.03.010

[Abstract](308) [PDF 478KB](108)

Abstract:
Aiming at the problem of insufficient positioning accuracy and stability of BDS least squares pseudorange difference method, a new pseudorange difference algorithm based on Kalman filtering method is proposed. Experiments under static and human walk dynamic conditions are carried out. After analyzing the measured data, the results from Kalman filtering method improves the accuracy in the east, north and up directions by 55％, 23％ and 48％ respectively under static conditions. Under dynamic conditions, the accuracy in the east, north, and up directions increased by 71％, 49％, and 33％, respectively.

Indoor location method of monocular vision fusing inertial navigation information

LI Mengzhen, YU Min, YU Jiahao

2019, 44(3): 74-80. doi: DOI:10.13442/j.gnss.1008-9268.2019.03.011

[Abstract](245) [PDF 783KB](115)

Abstract:
Aiming at the problem of high positioning accuracy but unstable data sources in monocular vision positioning method, and accumulative errors in inertial measurement unit (IMU) which can obtain positioning data steadily, a monocular vision indoor positioning method is proposed, which integrates inertial navigation information. The method uses fourparameter fitting model to convert the image data into positioning and attitude data, and introduces complementary filtering to correct the gyroscope reading in the inertial data solving process. Finally, the processed data is input to extended Kalman filter. as observation value to obtain the optimal position in formation. The experimental results show that the method can effectively improve the accuracy and stability of indoor positioning.

Application of Linux shell in ionospheric TEC grid data extraction and analysis

LI Yongtao, LI Jianwen, GU Chenzhong, CHEN Chen, ZHANG Shuo, CHE Tongyu

2019, 44(3): 81-87. doi: DOI:10.13442/j.gnss.1008-9268.2019.03.012

[Abstract](255) [PDF 1631KB](97)

Abstract:
The ionospheric delay is an important error source that cannot be ignored in satellite navigation and positioning. The global ionospheric TEC grid (GIM) data is very convenient to users because it provides TEC values at regular grid points globally. Based on the advantages of simplicity, high efficiency and easy maintenance of Linux Shell, this paper uses Linux Shell script to extract and analyze the ionospheric TEC grid data, including global and optional area ionospheric TEC data extraction, mean calculation, latitude and longitude grid difference calculation, and maximum and minimum value extraction. Therefore, some references could be provided for the analysis and research of annual, seasonal, weekly and daily variation characteristics, and some other temporal and spatial variation characteristics of global or regional ionospheric TEC based on GIM data.

Validation analysis of GNSS survey+level refinement model replacing grade leveling measurement

CHEN Zhenfang, WANG Jiexian

2019, 44(3): 88-94. doi: DOI:10.13442/j.gnss.1008-9268.2019.03.013

[Abstract](324) [PDF 781KB](137)

Abstract:
Based on the high-precision quasi-geoid refinement model of Jiaxing City and the JXCORS of Jiaxing City, combined with the results of the construction of modern surveying and mapping datum system and the reconnaissance of two projects in Jiaxing City, The derivation calculation and test analysis comparison of GNSS static measurement and network RTK measurement instead of grade leveling measurement are carried out. Finally, the feasibility of replacing grade level measurement is verified, which has a good application value for Urban Surveying and mapping.

Research on geological disaster monitoring technology based on CORS station

WEN Xu, LIU Li, LUO Mengwei, ZHANG Yizhi, WANG Lu

2019, 44(3): 95-98. doi: DOI:10.13442/j.gnss.1008-9268.2019.03.014

[Abstract](386) [PDF 533KB](107)

Abstract:
The continuous and real-time observation data of CORS base station are processed and analyzed by high-precision data processing software. The horizontal and vertical ground deformation and the change of ground gravity are studied by combining the observation data of atmosphere, surface water and sea level change. By tapping the potential of CORS benchmark station network to monitor the process of geological disasters, we enhance the ability of monitoring and early warning of geological disasters, promote the development of early warning of geological disasters towards quantitative and practical direction, and provide support for major engineering construction and safe operation in Zhejiang Province.

Design and implementation of intelligent early warning system for slope monitoring based on BDS

WANG Di, ZOU Bang, WEN Jing, GOU Qin

2019, 44(3): 99-104. doi: DOI:10.13442/j.gnss.1008-9268.2019.03.015

[Abstract](381) [PDF 741KB](116)

Abstract:
The traditional side slope monitoring technology has a series of disadvantages, such as low degree of automation, slowly report of warning situation and long response time. In order to overcome the shortcomings of traditional technology, an intelligent early warning system for slope monitoring based on BDS is proposed. The system is equipped with high-precision receivers, whose plane and elevation monitoring measurement can be millimeter level. In the disaster judgent, the system combines the traditional point stability analysis method and the current relatively new image movement discrimination technology, which further reduces the false alarm rate of disaster. The system is highly integrated, automatic and intelligent with vast functions such as data processing, data storage, data analysis, information management, disaster warning and crossplatform information distribution. It has been proved that the system could run properly and reduce the burden of the manager after a period of time of practice, which implies the system has certain popularization value.

Aerial UAV kinematic positioning using combined GPS／BDS system

GAO Xiao, KU Xinbo, BAI Hao, TANG Xinzhuang

2019, 44(3): 105-110. doi: DOI:10.13442/j.gnss.1008-9268.2019.03.016

[Abstract](386) [PDF 575KB](130)

Abstract:
Position and orientation system (POS) can acquire the line and angle elements of the aerial photographs directly, which can reduce the workload of unmanned aerial vehicle photogrammetry and improve work efficiency, thus the UAV photogrammetry has become an important way of data acquisition in aerial photogrammetry. For the large quality of conventional RTK products, it is difficult to be applied in the UAV surveying. In this paper, Doppler smoothing algorithm has been adopted to refine code observables, and then the combined Doppler-smoothed code (DSC) and phase data have been used to realize UAV post processed kinematic positioning (PPK). The results of measured data have shown that,compared with single satellite system, the combined GPS／BDS system can meet the requirement of kinematic positioning for UAV photogrammetry, and the efficiency and reliability of PPK positioning can be improved based on the DSC and phase observables.

Research on large deformation extraction algorithms based on BDS tri-frequency signal

TAN Bing

2019, 44(3): 111-116. doi: DOI:10.13442/j.gnss.1008-9268.2019.03.017

[Abstract](241) [PDF 621KB](99)

Abstract:
A single epoch algorithm for extracting large deformation from BDS triple frequency carrier phase signal is proposed. Based on the pre-deformation coordinates of monitoring points, this algorithm uses BDS three-frequency signal to construct ultra-wide roadway combination, uses data processing strategy without whole-cycle problem to obtain rough deformation values, and refines the original observation walues of wide roadway and L1 to obtain accurate deformation information step by step. The feasibility of the proposed algorithm is verified by testing a set of measured deformation data on the deformation monitoring test platform.

GPS elevation time series prediction model based on wavelet denoising technique and neural network

ZHANG Shisen, SUN Xiankun, YIN Ling, LI Shixi

2019, 44(3): 117-125. doi: DOI:10.13442/j.gnss.1008-9268.2019.03.018

[Abstract](423) [PDF 1044KB](101)

Abstract:
In the work of GPS time series data prediction, it is found that the noise contained in the time series data usually interferes with the results of data prediction. In order to minimize the negative impact of noise on prediction results in time series data as much as possible, a GPS time series data denoising prediction model is realized by combining lifting wavelet threshold denoising technology with long Short-Term Memory (LSTM). The model first uses lifting wavelet and smoothing threshold function to remove noise from GPS time series data before prediction, and then constructs a multi-layer LSTM neural network to predict time series data in one step. Compared with many time series prediction models, the results show that the proposed LSTM prediction model has strong applicability and higher accuracy for GPS time series prediction.

Analysis of residual impact of temperature and weather on IGS station joint measurement

YANG Chenglin, XU Baishan, HAN Zhonghan

2019, 44(3): 126-130. doi: DOI:10.13442/j.gnss.1008-9268.2019.03.019

[Abstract](353) [PDF 547KB](98)

Abstract:
Aiming at the problems of the GNSS service station (IGS tracking station) joint measurement residual impact in a year, the relationship between the weather conditions of average temperature change, rain and snow and IGS statio joint residual is summarized, and the factors affecting the joint measurement accuracy of IGS tracking station are judged. It is suitable for the stability test of the base stations in and around China, and the standardized root mean square error average (NRMS) is used to evaluate and improve the accuracy by avoiding the influence of precision factors. Finally, the CHAN station of 2018 is selected as the unknown site. The four IGS stations (BJFS, DAEJ, SHAO, ULAB) around the northeastern region of China are jointly tested. The GAMIT／GLOBK software is used for high-precision baseline processing, and the data of 2017 is selected to Check it out. The experimental results show that average temperature and rain and snow weather are two factors affecting the joint measurement residual of IGS tracking station. The average temperature and NRMS value are negatively correlated, and the correlation is greater than 60％. The combined effect of rain and snow weather is poor. Compared with non-rain and snow weather, the NRMS value is about 0.5 mm, and the combined accuracy of snowfall weather is the lowest. It is not recommended to conduct joint testing tasks in rain and snow.

The teaching reform and reflection of the optimal estimation course for the specialty of navigation engineering

WU Yun, JIANG Jing, ZHAI Juan

2019, 44(3): 131-134. doi: DOI:10.13442/j.gnss.1008-9268.2019.03.020

[Abstract](205) [PDF 466KB](211)

Abstract:
In order to match the needs of the following curriculums in the specialty of navigation engineering and the current developments of navigation technologies, the teaching reform has been implemented on optimum estimation course arming at the integration of theory and practice. This paper introduces the requirements of navigation engineering specialty for optimum estimation course. Then the teaching idea of this course is analyzed. The reforming implementations, such as the course content modification, textbook improvement, teaching methods and means are discussed. Finally, the current problems are considered and the improvement plans are proposed.