GNSS World of China

2018 Vol. 43, No. 3

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Application of Improved Adaptive Filtering Algorithm in BD/INS Integrated Navigation
QIANG Minghui, JIANG Wen
2018, 43(3): 1-6. doi: 10.13442/j.gnss.1008-9268.2018.03.001
Abstract:
Since the navigation performance and robustness of the integrated navigation system which combines the BeiDou and inertial navigation system are poor,the paper proposes a new algorithm under uncertainty noise interference, which bases on the attenuation factor and noise weighted adaptive Kalman filter technology. The paper first conducts simulation experiments with Matlab,comparing the traditional Kalman filter technology to verify the effectiveness of the new algorithm.Then the data postprocessing experiment of UAV is carried out. The results show that the improved adaptive filter algorithm can effectively increase the interference immunity of the integrated navigation system, thus improving the navigation performance and robustness.
Study and Evaluation of GNSS Signal Cryptographic Authentication Defenses
SHEN Chengliang, GUO Chengjun
2018, 43(3): 7-12. doi: 10.13442/j.gnss.1008-9268.2018.03.002
Abstract:
Due to the public signal structure of the global navigation satellite system (GNSS) civil signal, civil receivers are threatened by a variety of spoofing attacks. For different spoofing attacks, the robustness of different authentication techniques is compared and analyzed. The analysis shows that authentication techniques fail to handle forward spoofing attacks. Based on the comparison of elliptic curve digital signature (ECDSA) and time effect stream loss authentication (TESLA), the navigation information authentication (NMA) scheme of combination of ECDSA and TESLA is proposed. The proposed authentication scheme solves the problem of the computation and time synchronization of the traditional NMA techniques. Finally, the spreading code authentication (SCA) technique is used as an example to evaluate the performance of the cryptographic authentication techniques by simulation. The simulation shows that authentication can greatly improve the antispoofing performance of civil receivers.
Application of K-means++Partition Method in Intensive Stations
HAO Meiyun, SUN Xiankun, DING Qianyun, YIN Ling, YIN Jingyuan
2018, 43(3): 13-20. doi: 10.13442/j.gnss.1008-9268.2018.03.003
Abstract:
GAMIT software generally needs to perform partition processing when solving large-scale intensive stations. Partition resolution has a certain influence on the accuracy of the results. In order to solve the problem that the long-short baselines exist in the general partitioning method and the accuracy of the whole network solution is reduced, the K-means++algorithm and the Hash algorithm are introduced to implement partitioning, which is referred to as the K-means++partition method. First, using K-means++algorithm to cluster stations, and then using Hash algorithm to sort and combine, so that we can obtain an uniform distribution subnet. In this paper, the result of the whole network solution is used as the standard value. The baseline length, baseline accuracy and three-dimensional coordinate difference of the regional zoning method and the K-means++zoning method are analyzed. Then the K-means++partition method and the spacing zoning method are compared and analyzed. The experimental results show that this method is more accurate than the regional zoning method, and it is in line with the accuracy of the existing spacing zoning method, and is more stable and efficient than the zoning method.
  Application of Lagrange Interpolation Method in BeiDou Satellite Precise Ephemeris Interpolation
LI Zhenchang, LI Zhongqin
2018, 43(3): 21-25. doi: 10.13442/j.gnss.1008-9268.2018.03.004
Abstract:
It is necessary for precise ephemeris to be interpolated in high-precision satellite positioning data processing. In this paper,based on the sliding Lagrange interpolation method,it is investigated that the relationship between the interpolation order and the interpolation accuracy of three kinds of Beidou satellites in BeiDou precision ephemeris respectively. The example shows it is different that the interpolation order of the three kinds of BeiDou satellites to achieve the best interpolation precision; as long as a reasonable order is adopted,three kinds of satellites can all achieve millimeter interpolation precision. This method can be better applied to the interpolation of the precision ephemeris of the BeiDou satellite,and this method is completely suitable for interpolating the precision ephemeris of the BeiDou satellite.
Algorithm Study on the Earth Rotation Parameters with the Combination of VLBI and BDS
LIU Cong, MENG Pengfei, LIU Xin
2018, 43(3): 26-31,38. doi: 10.13442/j.gnss.1008-9268.2018.03.005
Abstract:
The earth rotation parameters (ERP) are estimated by MGEX station’ data collected in 2016 from 61 to 91 days with PANDA. The ERP are estimated by processing VLBI data during the same period with VieVS2.2. The results of BDS and VLBI are combined in a weighted way to get the comprehensive ERP value, based on IERS 08C04. The comparisons show that the RMS values of the differences between the series given in this paper and IERS series are 0.249 mas in x-component of polar motion(X-Pole), 0.296 mas in y-component of polar motion(Y-Pole), 0.053 ms in UT1-UTC. The joint calculation of ERP parameters by BDS and VLBI data makes up for the instability of the BDS calculation results and the discontinuity of the VLBI observation, so that the stability and reliability of the results are improved.
The Effect of Local Tide on Precision Positioning in Shanghai
DING Qianyun, SUN Xiankun, YIN Ling, HAO Meiyun, YIN Jingyuan
2018, 43(3): 32-38. doi: 10.13442/j.gnss.1008-9268.2018.03.006
Abstract:
In view of the differences of the global tidal model in different coastal areas and the poor accuracy of offshore in China,using the global tide models FES2004 and NAO99b to calculate the vertical component of the tidal load displacements of the four tide components S2、M2、K1and O1 in Shanghai (The range from 120.85 to 122.2 East longitude, 30.6667 to 31.8833 West latitude).In order to calculate the effect of local tide on the precise positioning of four stations of SHJZ station (Shanghai Jinshan), SHJBS station (Shanghai Baoshan), SHAO station (Shanghai Sheshan) and DCMD station (Shanghai Chongming), using the Chinese offshore model osu.chinasea.2010 to replace the corresponding region in the global tide model FES2004.The results show that: (1)There are obvious differences between the global tide models FES2004 and NAO99b in Shanghai, especially in the vertical components. The maximum is close to 4 mm, and the difference between the two models decreases with the distance from the ocean;(2)The influence of offshore effect on the precision positioning of GPS stations in Shanghai reaches 5 mm,and the influence on the vertical component of the station from big to small are DCMD station (5.1 mm), SHBS station (4.9 mm), SHJS (4.2 mm) and SHAO (3.6 mm) respectively.
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:
Multi-source navigation information fusion algorithm is the core technology of multi-source fusion navigation system. According to the structure characteristics of various algorithms, fusion algorithms are divided into three categories: centralized fusion algorithm, parallel fusion algorithm and sequential fusion algorithm. Through the simulation of various algorithms, the characteristics and application scenarios of the algorithm are summarized, and the development trend of the fusion algorithm is obtained, which provides theoretical support for the design of multi-source fusion navigation system.
Development and Application of A GNSS Signal Record/Playback Equipment
ZHANG Tao
2018, 43(3): 45-50,55. doi: 10.13442/j.gnss.1008-9268.2018.03.008
Abstract:
In this paper, a GNSS signal record and playback equipment is designed and implemented. This device takes advantage of the fact that the frequency converter(mixer) produces difference frequency and sum frequency. In the recording and playback stage, different frequency conversion methods are used, and the sum frequency and the difference frequency in the frequency conversion result are respectively used, so that the unwanted band among multiple GNSS signals with a farther frequency center is removed, only leaving a useful signal.The cost and complexity of the equipment have been reduced so that the acquisition and playback can be done using the inexpensive SDR platform. The device has been proved to be able to record and play back signals such as GPS L1/L2 and BDS B1, and can be widely used in teaching experiments, research and development of GNSS receivers, and scientific research fields.
Fitting Accuracy Analysis of Satellite Coordinate Based on BDS Broadcast Ephemeris
LIU Shuangtong, WANG Mingxiao, YANG Shuwen, YANG Mingze, YANG Lihua
2018, 43(3): 51-55. doi: 10.13442/j.gnss.1008-9268.2018.03.009
Abstract:
Aiming at the question of repeated calculations and low efficiency when calculating satellite positions using the broadcast ephemeris,this paper proposes the use of Chebyshev polynomials to fit satellite orbit for broadcast ephemeris by calculating the satellite coordinates of some fixed time intervals as known nodes. Using different fitting orders to find difference between the fitting point and the corresponding point obtained by the direct method and analyzing the fitting accuracy.The examples show that the broadcast ephemeris fitting accuracy can meet the requirements as long as the fitting time interval and the fitting order are taken properly.
Adaptive CORS RTK Single Base Station to Improve the Measurement Accuracy of the Kalman Filter
CHEN Changkun, YU Xuexiang, SHI Changwei, XIAO Ming, SU di
2018, 43(3): 56-61,66. doi: 10.13442/j.gnss.1008-9268.2018.03.010
Abstract:
For the single base station CORS RTK has low measurement accuracy in surface deformation monitoring of mining subsidence, an adaptive Kalman filter algorithm based on variance estimation principle is constructed. Correspondence CORS RTK is used to collect the plane coordinates and normal height of each epoch. Based on the actual CORS RTK measured data and comparative analysis results of the fourth-class level measurement, the CORS RTK measurement accuracy after filtering has been greatly improved, which meets the accuracy requirements for surface movement deformation monitoring of mining subsidence.
Data Quality Analysis of CORS in Heilongjiang
ZHAO Zhonghai
2018, 43(3): 62-66. doi: 10.13442/j.gnss.1008-9268.2018.03.011
Abstract:
In order to understand the data quality of the HLJCORS, we use TEQC software to process the HLJCORS data in year 2017 to get a comprehensive analysis and statistics. The results indicate that the data quality of HLJCORS is high which it provides a reference for the key maintenance of the base station.
Precision Checking Method and Example of Long Distance GPS RTK Measurement
HU Tao
2018, 43(3): 67-69. doi: 10.13442/j.gnss.1008-9268.2018.03.012
Abstract:
 Drilling is an important part of petroleum exploration and development work and is also a high investment, high risk industry, especially drilling a well in desert areas often needs tens of millions of money. It is the precondition and basis for the drilling to reach the predetermined target. GPS RTK technology has advantages of high flexibility, high accuracy, low construction cost and high operating efficiency. In the desert region with few people, flat terrain, low occlusion and small electromagnetic interference, the advantage of GPS RTK technology is more obvious in the location measurement work. However, the distance between GPS RTK technology positioning is strictly limited. In general, no more than 10 km can be extended to 15 km under special circumstances. So, what is the accuracy and reliability of GPS RTK technology positioning for distances of over 15 km? In taklimakan desert area,by adopting GPS RTK technology, the distance is greater than 15 km of two known control points for measurement analysis, whith is verified for GPS RTK surveying precision of the long distance in desert regions.
Spatial and Temporal Characteristics Analysis and Model Establishment of  Weighted Average Temperature in Gansu Province
GAO Zhiyu, LI Jianzhang, KOU Ruixiong, LI Zhenchang, CHEN Chen
2018, 43(3): 70-76. doi: 10.13442/j.gnss.1008-9268.2018.03.013
Abstract:
The weighted average temperature is an important parameter in the research of atmospheric precipitable water vapor, which directly affects its precision. In view of the less weighted average temperature model suitable for Gansu Province and the low accuracy of existing models, we mainly use the data of 7 atmospheric sounding stations in Gansu from 2013 to 2017, and statistically analyze the spatial and temporal characteristics of the weighted average temperature in Gansu Province. Then based on the principle of least squares, localized partition, sub-quarter and sub-month models are established, and the accuracy of the model is verified by the existing models. The results show that the weighted average temperature in Gansu has obvious spatial and temporal characteristics. Therefore, it is very necessary to establish partition, sub-quarter and sub-month models. The precision of partition, sub-quarter and sub-month models is better than the existing models, which has important practical value.
Influence of Sampling Distance on Positioning Accuracy of WiFi Fingerprint Positioning
LUO Yufeng, LIU Yanhui, LI Xiaochun
2018, 43(3): 77-81,94. doi: 10.13442/j.gnss.1008-9268.2018.03.014
Abstract:
On the Android platform, we design and use WiFi signal strength characteristics to locate. The location system in this paper is made up of Android client, Tomecat server and MySQL database.Based on the RSSI WiFi fingerprint positioning in the offline establishment of the fingerprint database by the sampling distance of the impact, the sampling distance can inevitably affect the accuracy of fingerprint positioning. In order to explore the effect of sampling pitch on WiFi fingerprint positioning, the experiment is carried out in the classroom. Select a different sampling interval to carry out WiFi fingerprint positioning, and we measure the positioning accuracy and timeliness as the positioning result. Experiment results show that: in indoor environment, the sampling interval is 3 m,the timeliness is higher and the positioning accuracy can meet the requirements.
Construction and Applicability Analysis of Regional Atmospheric Weighted Average Temperature Model
WANG Pengyuan, LI Fei, ZHENG Nanshan
2018, 43(3): 82-87. doi: 10.13442/j.gnss.1008-9268.2018.03.015
Abstract:
As an important parameter in atmospheric water vapor inversion by GNSS, weighted average temperature directly affects the inversion accuracy of atmospheric Precipitable Water Vapor (PWV), and establishment of a localization-weighted average temperature model is helpful to improve water vapor inversion accuracy. Based on the analysis of the relationship between the weighted average temperature and the surface meteorological elements by using Hong Kong sounding station’s data from 2012 to 2015, single-factor model and muti-factor model of the regional weighted average temperature are established with the least square principle which is used to explore the optimal regression equation coefficients. The results show that the accuracy of the multi-factor model is higher than that of the single-factor model, but it is not significant. The Bevis empirical formula does not meet the accuracy requirements when applied to the Hong Kong region; the accuracy and applicability of the model are analyzed and compared, indicating that the accuracy of the model established in this paper is high, and it can better meet the high-precision requirements of water vapor remote sensing.
  Research of Local Model of Weighted Mean Temperature of CORS Water Vapor Retrieval in Qingdao
LI Fei, LIU Zhimin, LI Yangyang, GUO Jinyun
2018, 43(3): 88-94. doi: 10.13442/j.gnss.1008-9268.2018.03.016
Abstract:
Atmospheric weighted mean temperature is a key parameter in CORS water vapor retrieval, and its variations are obvious in both time and space. In order to improve the accuracy and reliability of the atmospheric CORS, the surface temperature Ts and the weighted mean temperature Tm acquired by radiosonde station during 2009 to 2011 in Qingdao are analyzed. The correlation coefficient R of Ts and Tm is 0.877 6, which is strong linear correlation. The weighted mean temperature model of Qingdao area is established by regression analysis, and the weighted mean temperature in 2012, Qingdao is calculated. Compared to the weighted mean temperature calculated by radiosonde data, the average deviation, standard deviation and root mean square error are respectively 0.307 K, 3.359 K and 3.384 K. The model is applied to CORS water vapor retrieval in Qingdao, and the average deviation, standard deviation and root mean square error are respectively 0.70 mm、3.48 mm and 3.53 mm. The results show that it is feasible to apply the regional radiosonde data to establish the weighted mean temperature model and to improve the accuracy and reliability of the regional CORS water vapor retrieval to a certain extent.
Application of Single Base Station CORS-RTK in Mine Settlement Observation
XU Jianglin, HUANG Hui, ZHAO Yong, LIU Kesheng, YU Xuexiang
2018, 43(3): 95-99,106. doi: 10.13442/j.gnss.1008-9268.2018.03.017
Abstract:
 Single base station CORS-RTK has its own unique advantages over multistation CORS-RTK and network RTK. Based on an example of surface movement deformation in Huainan mine, this paper analyzes the measurement precision of single base station CORS system, coordinates data and error. The results show that the measurement data of single base station CORSRTK meets the requirements of precision, which is of great significance to reduce the work load of mine settlement observation.
Performance Analysis of PPP in Mode of PPP_AR
ZHANG Guoli, ZHANG Jingkui, YANG Kaiwei
2018, 43(3): 100-106. doi: 10.13442/j.gnss.1008-9268.2018.03.018
Abstract:
In this paper, we use one a week data(the sampling interval of satellite clock is 30 s) of six IGS tracking stations to test the positioning accuracy and convergence time under PPP fixed ambiguity pattern-PPP_AR mode and conventional float solution mode. The results show that under PPP_AR solving mode, and for selfconsistency between the data, positioning accuracy of RMS can be smaller than 1 cm in both E-W and N-S directions, and in the U-D direction smaller than 3.5 cm, The results are obviously better than that of the conventional floatingpoint solution mode. The ambiguity fixed rate under PPP_AR mode is larger than 93%, the convergence time of PPP_AR mode focused on 20~25 min, while of the float solution mode on 25~35 min.
Analysis of Bridge Health Status Based on TRACK[
YU Longhao, DING Keliang, LIU Mingliang, LIU Yajie, LUO Qijie
2018, 43(3): 107-111. doi: 10.13442/j.gnss.1008-9268.2018.03.019
Abstract:
Dynamic monitoring of bridges has always been the focus of research on the direction of engineering deformation monitoring. This paper simply introduces the TRACK module, and further expounds the principle of TRACK data processing and a bridge of experimental data. Using double differential dynamic positioning module TRACK of GAMIT/GLOBK10.61 in the measured data on the bridge of single epoch data postprocessing, we obtain time series of bridge vibration of bridge vehicle peak hours and night time. The time series of the bridge vibration is de-noising by the empirical mode decomposition method, and the effect of the vehicle on the health of the bridge is compared and analyzed, and the feasibility of the TRACK method for the bridge condition analysis is further verified.
Intelligent Navigation Strategy for Agaricus Bisporus Fresh Keeping Based on Clustering Algorithm
ZHANG Ziqi, CHEN Chengming
2018, 43(3): 112-117. doi: 10.13442/j.gnss.1008-9268.2018.03.020
Abstract:
Preservation technology during transportation is a key link in Agaricus bisporus industry. In order to choose the transportation route of fresh mushrooms more reasonably and adjust the real-time traffic information, an intelligent navigation strategy combined with the Beidou satellite navigation system is proposed. Firstly, the storage law of bis -mushroom is analyzed, and the realtime road condition is combined with the monitoring of the Beidou satellite navigation system. By using the clustering algorithm, a navigation strategy is made to select the most ideal transportation route intelligently. Finally, the feasibility of the strategy is verified by simulation.
The Design of the Fishing Vessel Monitoring System Based on BeiDou Satellite
CUI Xiufang, CAI Chenyu, LI Zhigang
2018, 43(3): 118-123. doi: 10.13442/j.gnss.1008-9268.2018.03.021
Abstract:
  A fishing vessel monitoring system based on BeiDou satellite is designed to solve the problem of fishing vessel distress search and rescue in time. This monitoring system realizes real-time monitoring of fishing vessel which takes Linux operation system as interactive platform, combines with computer technology and BeiDou satellite navigation technology. The location information of the fishing vessel is embedded into the built-in electronic map to realize the real-time monitoring and management of the ship's navigation state. The system makes full use of some advantages of wide range, high reliability, good stability of BeiDou, which solves the problem of insufficient network coverage in far-sea area. The experiment shows that the system achieves the design goal.
Analysis of AUV Positioning Performance in Shallow Ocean Based on GPS/BDS Combination
JIANG Shaojie, WANG Xian, LIU Haidi, XIA Changchun
2018, 43(3): 124-128. doi: 10.13442/j.gnss.1008-9268.2018.03.022
Abstract:
  In order to solve the problem of large positioning errors when underwater robots work in shallow seas, this paper focuses on the high-precision positioning and navigation system for shallow seawater robots based on GPS/BDS dual-mode combined positioning technology under the condition of shallow sea electromagnetic wave signal attenuation characteristics. In order to compare the positioning performance of the dual-mode positioning system, the GPS and BDS single-mode positioning system is set up. The positioning data processing method using a median filtering algorithm and a Kalman filtering algorithm is proposed to test the dual-mode positioning system and we use filtering data to get the system's positioning performance. The test results show that: the positioning accuracy of the dual-mode positioning system is higher than that of the single-mode positioning system and the application of the median filter and the Kalman filtering algorithm can significantly improve the positioning accuracy of the dual-mode positioning system.
A High Efficient Method of Downloading GNSS Data Automaticly
WANG Cheng, LI Lei, ZHANG Mingbin
2018, 43(3): 129-134. doi: 10.13442/j.gnss.1008-9268.2018.03.023
Abstract:
 Traditional method of GNSS data download wastes too much time in loging in and out the empty folder. To solve this problem, this paper proposes an improved method. The principle of this method is obtaining the filename of the GNSS data which is stored under the path of ftp in advance, and then using the data download command to download the data. This method can avoid the disadvantage of the traditional method and improve the efficiency of data downloaded greatly. It can be seen from the results of the experiment that this method can save about 34 min in downloading data from IGS and 17 min form MGEX in average comparing to the traditional method. Thus, this method can actually improve the efficiency of data download.