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Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
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Research on water extraction method based on GF-5 hyperspectral feature analysis
SHEN Congying, GAN Shu, LI Xin’ao, FENG Hongneng
 doi: 10.12265/j.gnss.2021030901
[Abstract](39) [FullText HTML](26) [PDF 870KB](4)
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In view of the spectral confusion between mountain water body, mountain shadow and bare land, a decision tree extraction model for mountain water body is constructed based on Gao Fen-5(GF-5) image data combined with hyperspectral feature analysis. First, perform hyperspectral feature analysis on the water body and related interference types to realize the selection of feature bands, apply single-band threshold method, multiple-band spectral relationship method, and NDWI method to extract experiments. By comparing the deficiencies of the above experiments, a single-band threshold is proposed. The decision tree water body extraction model combined with the constructed shadow water index (SWI) is used to evaluate the accuracy of the confusion matrix obtained by using Google Earth high-definition images as a reference and on-site sampling. The experimental results show that the single-band threshold method and NDWI method can easily identify mountain shadow as water body and are less affected by bare land; the multiple-band spectrum relationship method has a certain inhibitory effect on mountain shadow and is affected by small areas of bare land; decision tree model can effectively suppress the influence of mountain shadow and bare land to extract complete water body. The overall accuracy is 89.39%, and the Kappa coefficient is 0.82, which significantly improves the extraction accuracy of mountain water body.
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2021, (4): .  
[Abstract](43) [FullText HTML](28) [PDF 1911KB](12)
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2021, 46(4): 1-1.  
[Abstract](45) [FullText HTML](24) [PDF 29530KB](6)
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A summary of research on GNSS-R signal-to-noise ratio signal height measurement technology on the sea
HU Yuan, ZHONG Licheng, CHEN Xingyang, GU Wangwang, LIU Wei
2021, 46(4): 1-7.   doi: 10.12265/j.gnss.2021011502
[Abstract](104) [FullText HTML](53) [PDF 1097KB](22)
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Since the concept of Global Navigation Satellite Reflected Signal (GNSS-R) was proposed, GNSS-R has been widely used in remote sensing, and has been used in sea surface height measurement, sea surface wind field inversion, sea ice detection and other aspects. This article mainly introduces the application and research progress of GNSS-R remote sensing technology in sea surface height measurement. Highlights the research progress based on signal-to-noise (SNR) ratio data measurement methods, and briefly describes the theory and signal processing methods involved in SNR ratio data measurement methods and according to the current research progress. The future development direction of sea surface altimetry is prospected.
Evaluation and analysis of different global ionospheric maps over China
SHENG Chuanzhen, ZHANG Jingkui, ZHANG Baocheng
2021, 46(4): 8-15.   doi: 10.12265/j.gnss.2021012703
[Abstract](90) [FullText HTML](44) [PDF 1147KB](16)
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We systematically evaluated and analyzed the performance of predicted, rapid and final global ionospheric map (GIM) products, provided by 5 IGS ionospheric analysis centers and the international GNSS Monitoring and Assessment System (iGMAS) comprehensive center, over China. The ionospheric total electron content (TEC) values measured by Global Navigation Satellite System (GNSS) and Jason altimeter satellites are selected as references and performances of GIM in standard single-point positioning are also used as indices in the validation. The results showed that the order of performance from high to low of different types of GIM over China is the final GIM, the rapid GIM and the predicted GIM products. Different GIM products are found to have comparable performances over China during low solar activity. The rapid and final GIM products provided by the Universitat Politècnica de Catalunya (UPC) and iGMAS outperform other GIM products during high solar activity.
Design of BPM HF signal based on DDS
LAI Wenbin, LI Shifeng
2021, 46(4): 16-21.   doi: 10.12265/j.gnss.2020111901
[Abstract](57) [FullText HTML](32) [PDF 1112KB](8)
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BPM HF timing service is a kind of economical and convenient timing service method, which uses short wave radio station to transmit and broadcast the standard time and frequency in China. In order to solve the developing and testing problem of BPM applications, we analyze the characteristics of the BPM HF signal and use the direct digital synthesizer (DDS) technology. In addition, field-programmable gate array (FPGA) and digital to analog converter (DAC) are used as the core hardware platform to complete this design. The theoretical calculation and simulation results prove that the design worked well and it can surely promote the development of BPM HF timing technologies.
A number of hops-corrected and hop distance optimization-based DV-Hop localization algorithm
ZHANG Yuan, WANG Mei, MIAO Xianglin, DING Huang
2021, 46(4): 22-26.   doi: 10.12265/j.gnss.2020121001
[Abstract](51) [FullText HTML](35) [PDF 885KB](10)
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Aiming at the problem of low localization accuracy of classical DV-Hop algorithm, caused by calculation of hop count and hop distance, number of hops-corrected and hop distance optimization-based DV-Hop localization (NHDL) algorithm is proposed in this paper. In NHDL algorithm, the received signal strength values among nodes are used to correct the number of hops. Then, the average distance of each hop of anchor nodes is modified by weighting factor. And the anchor nodes are selected through the concept of collinearity to reduce the localization error. The min-max method is adopted to calculate the position of node. The simulation results show that compared with the traditional DV-Hop algorithm, the average error of localization is reduced.
Terrain optimization method for low-frequency ground-wave propagation delay calculation
ZHU Zhiya, GUO Wei
2021, 46(4): 27-32.   doi: 10.12265/j.gnss.2021012501
[Abstract](65) [FullText HTML](19) [PDF 1045KB](5)
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The additional secondary phase factor (ASPF) plays an important role in propagation delay of the low-frequency ground-wave. A method of calculating attenuation for ground-wave propagating over irregular terrain called integral function has been developed recently. It is derived by means of a stationary-phase integration that reduces the dimensionality of the general version, but such an approximation is not valid for all terrain types. The terrain of the actual propagation path changes greatly, and the actual propagation path is corrected by the mathematical morphology method to keep the basic geometric contour and smoothness of the path. The calculation results of the integral equation method show that the actual propagation path can be effectively optimized through the mathematical morphology method.
Combined method of wavelet and MPCA for high-rate GNSS signal denoising
LI Baojin, LI Yanyan
2021, 46(4): 33-39.   doi: 10.12265/j.gnss.2021020601
[Abstract](54) [FullText HTML](17) [PDF 1006KB](6)
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In view of the problem that traditional principal component analysis (PCA) ignores the correlation between coordinate components of stations, a method combining wavelet denoising and multi-directional principal component analysis (WD-MPCA) is proposed, which makes up for the shortcomings of traditional PCA. Compared with empirical mode decomposition and principal component analysis (EMD-PCA) and wavelet denoising and principal component analysis (WD-PCA). The WD-MPCA combination method has the highest accuracy. After denoising by WD-MPCA combination method, the mean median error is 0.83 mm, 0.85 mm and 8.30 mm respectively, which is 81.14%, 81.91% and 40.37% lower than that of the original coordinate residual time series. The WD-MPCA combination method fully considers the correlation between different components of each station. It can effectively remove high-frequency random white noise (WN) and low-frequency colored noise (CN), which is of great significance to the practical application and theoretical development of high-frequency Global Navigation Satellite System (GNSS) technology.
The detection method of wrecked plane's black box based on SCOUT+ ultra short baseline positioning system
LU Qingqing, GUO Jinyun, QIN Jian
2021, 46(4): 40-44.   doi: 10.12265/j.gnss.2021040701
[Abstract](121) [FullText HTML](20) [PDF 838KB](6)
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The black box of wrecked aircraft, as the witness of air disaster, need to be salvaged quickly. In the ocean environment of twenty meters deepth, we search to locate the aircraft black box based on SCOUT+ ultra-short baseline positioning system (USBL). The black box simulator is located in 20 m water depth ocean environment. The positioning accuracy reaches 6.35 m, and the angle positioning accuracy reaches 2.78°. After eliminating the fixed error of installation, the angle positioning accuracy reaches 0.40°. In general, the SCOUT+ detecting accuracy of the black box reaches the expected requirement and meet real needs.
Design and implementation of isolator management system based on GNSS and network communication fusion positioning
LU Tianzeng, ZHEN Weimin, MA Baotian, LIU Shaolin, TAN Shuai
2021, 46(4): 45-51.   doi: 10.12265/j.gnss.2021053101
[Abstract](32) [FullText HTML](34) [PDF 8757KB](10)
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In response to the difficulty in management and control of entry-exit personnel from high-risk epidemic areas during the isolation period, the article designs an "Isolation Housekeeper" management system based on the fusion positioning of Global Navigation Satellite System (GNSS) and network communication. The system relies on GNSS positioning, Cell-ID positioning, WLAN positioning, cloud computing platform, geographic information system and other technologies, to realize the functions of isolated people positioning, motion trail reporting, electronic fence setting, body temperature reporting, body temperature monitoring, out of circle warning, motion trail tracking, etc. This system can provide the enterprises and institutions with safe and effective hierarchical management of each isolated person, so as to achieve registration, real-time control, and trajectory traceability.
Design and experiment of centimeter UWB ranging error correction model based on BP neural network
XIAO Tingyang, ZHANG Di
2021, 46(4): 52-58.   doi: 10.12265/j.gnss.2021032901
[Abstract](57) [FullText HTML](24) [PDF 1282KB](10)
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In complex indoor environment, ultra wide band (UWB) ranging error can not be effectively compensated by conventional methods, which seriously restricts its positioning accuracy. Based on the analysis of the distribution characteristics of UWB ranging error in indoor environment, two different BP network error correction models with different structures are designed. Model BP1 inputs the ranging values of a single label and four base stations, and outputs four corresponding ranging errors; Model BP2 inputs the three-dimensional coordinates of a pair of labels and a base station, and outputs one corresponding ranging error. The network is trained with high precision total station measurement result as reference value, and the ranging and positioning accuracy before and after model correction are compared and analyzed. The results show that both models can effectively correct ranging errors and improve positioning accuracy. BP1 ranging and positioning accuracy are improved by 83.0%, 75.9%, and BP2 ranging and positioning accuracy is improved by 91.7%, 93.8% on average. BP2 can improve the ranging and positioning accuracy more effectively than BP1, and the positioning accuracy can be improved from decimeter level to centimeter level.
Performance evaluation of GNSS ionospheric constraint single-frequency PPP
LI Zhong, GE Haibo, BU Yuhang
2021, 46(4): 59-65.   doi: 10.12265/j.gnss.2021052701
[Abstract](54) [FullText HTML](34) [PDF 1101KB](4)
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In allusion to two commonly used models in single frequency precise point positioning (SF-PPP): SF-PPP with raw and uncombined observations(SF-UC-PPP) and SF-UC-PPP with the constraint of ionospheric delay, considering simultaneously the three different ionospheric delay constraint strategies including constant, step wise relaxed and spatial-temporal strategy, these models are compared and analyzed in positioning accuracy and convergence time using GPS and GPS+BDS data. The experiment result shows that by using the GPS system observations these three models with ionospheric delay constraint can significantly improve the convergence speed of PPP, the step wise relaxed model is the fastest. Its average convergence time is 32.36 min. Accuracy of these four models after convergence is roughly equivalent. By adding the BDS data, the convergence time of these models increases differently. The spatial-temporal model has the most significant improvement, which convergence time is shorted to 59.22% of single system. Aafter the using of BDS data, the accuracy of horizontal direction is improved by 0.5 cm to 1.3 cm, the vertical accuracy has slight decrease.
Application of GNSS elevation instead of the fifth grade leveling elevation in the survey project of existing railway renovation project
YAN Jianwei
2021, 46(4): 66-69.   doi: 10.12265/j.gnss.2021051801
[Abstract](40) [FullText HTML](22) [PDF 478KB](4)
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Real time dynamics of Global Satellite Navigation System (GNSS-RTK) technology has been widely used in various engineering fields. This article describes the principle and advantages of GNSS-RTK technology in railway reconstruction projects. Regional control network is used to collect leveling points, and the results are added to the point correction concentration for post-correction. By comparing the results of existing railway reconstruction projects with those of leveling survey, it is concluded that RTK elevation can reach the accuracy of the fifth grade leveling elevation by adding a certain number of elevation points to participate in point correction, the similar project application has the certain reference significance in the plain or the mountainous area.
Characteristic analysis of coordinate time series of tide gauge station
FU Jie, XIONG Changliang, SUN Xiwen, HE Xiaoxing, ZHU Jixing
2021, 46(4): 70-75.   doi: 10.12265/j.gnss.2021020702
[Abstract](58) [FullText HTML](39) [PDF 1267KB](5)
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In this paper, 298 tide gauge stations are used as the research object, and three models of generalized gauss markov (GGM) noise model, autoregressive moving average (ARMA) noise model and Autoregressive fractionally integrated moving average (ARFIMA) noise model are used to estimate the noise model characteristics of the coordinate time series of tide gauge stations and the trend of sea level changes. The influence of time span on the velocity estimation of tide gauge stations analyzed and discussed. The experimental results show that the noise characteristics of coordinate time series of tide gauge stations are mainly ARFIMA(1,0), ARFIMA(2,2), ARMA (1,0); the velocity estimation results of tide gauge stations show that 64.77% of the station velocity values are in the interval of 0 mm/a to 4 mm/a, and the average sea level velocity is 1.25 mm/a, which is on an upward trend. As the time span increases, the velocity uncertainty of the coordinate sequence, of the tide gauge stations, gradually tends to converge from divergence, and a time span more than 110 a helps to obtain a robust estimate of the tide gauge station velocity.
Ionospheric TEC forecast model of based on CEEMD and GRNN
GAO Qingwen, ZHAO Guochen
2021, 46(4): 76-84.   doi: 10.12265/j.gnss.2020091401
[Abstract](263) [FullText HTML](347) [PDF 1898KB](26)
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Aiming at the problem of non-linear and non-stationary electrons in the ionospheric total electron content (TEC), and high noise caused by multiple factors, a CEEMD-GRNN ionospheric TEC prediction model combining the complementing ensemble empirical mode decomposition (CEEMD) and generalized regression neural network (GRNN) to solve the problem of poor fitting and low prediction accuracy caused by direct use of raw data for prediction. The ionospheric data of 2019 from IGS center for high, middle and low latitude are used. Different day of year data with magnetic storms and without magnetic storms are tested. Results show that the RMSE of low latitude is 0.97 and the relative accuracy is 91.28, which verifies that the accuracy of the CEEMD-GRNN forecast model is higher than that of the EMD-GRNN and the single GRNN model.
Quality assessment of Android smartphone with GNSS raw observations
ZHANG Yin, TU Rui, HONG Ju, LI Fangxin, HOU Furong
2021, 46(4): 85-92.   doi: 10.12265/j.gnss.2021042501
[Abstract](87) [FullText HTML](31) [PDF 1832KB](9)
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With the continuous construction of Global Navigation Satellite System (GNSS), the location-based service (LBS) of smart phones has rapidly developed. In this paper, several commonly used smartphone are selected as research objects, such as Samsung S9+(Exynos), Huawei Mate30, Huawei P40 Pro. the measurement receiver UR4B0-D from BDStar Navigation is used for synchronous static observation experiment. the GNSS raw data quality of Android smartphone is analyzed from the aspects of satellite visibility, carrier-to-noise ratio (CNR), satellite altitude angle, multipath error and so on. The results show that there are obvious differences in observation capabilities and data quality among different smartphones. Android smartphones have poor data quality and low CNR. The CNR of Android smartphones has no obvious relationships with the satellite altitude angle. In addition, multipath error is one of the main errors that affect the high-precision positioning of Android smartphones.
A method for designing the loop parameters of digital PLL based on equivalent signal model
FENG Fan, GONG Hang, ZANG Wenchi, CHEN Huaming
2021, 46(4): 93-100.   doi: 10.12265/j.gnss.2021020101
[Abstract](56) [FullText HTML](32) [PDF 2385KB](3)
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Ideally, the loop parameters of an digital phase-locked loop (DPLL) is determined by the intersection of the phase noise of the input signal and the voltage-controlled oscillator (VCO). However, the basic module of the phase-locked loop (PLL) will introduce noise into the PLL system, thereby affecting the PLL performance. The method of directly calculating the intersection point of the two cannot take into account the influence of module noise. With the theory of the power-law spectrum model, this paper uses the PLL transfer model to superimpose the noise of the basic module of the PLL on the signal model of the atomic clock and the VCO. After establishing new signal models, it can conveniently and quickly determine the optimal loop parameters of the PLL. The simulation shows that the loop parameters selected by this method can make the output signal have good frequency stability, which can provide theoretical guidance for the selection of the loop parameters of the digital phase-locked device used to purify the atomic clock signal.
Research on high precision positioning platform of smart phone based on CORS
LI Xiaohua, LI Wei, WANG Kaifeng, MA Ning
2021, 46(4): 101-105.   doi: 10.12265/j.gnss.2021020102
[Abstract](31) [FullText HTML](11) [PDF 1181KB](2)
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This paper studied the key technology of high-precision navigation and positioning based on CORS for smart phones, and formed a high-precision navigation and positioning solution for mobile terminals based on JS-CORS. At the same time, the software system was developed, including a set of mobile APP and a location management platform. The construction of high-precision positioning platform for smart phones based on CORS is of great significance to extend the multi applications of smart phones in geographic mapping, intelligent transportation, emergency rescue, public security and other aspects, and expands the application field of CORS as well.
The local carrier optimization technology in anti-jamming satellite navigation receiver
SONG Jie, LU Zukun, CHEN Feiqiang, YU Meiting, SUN Guangfu
2021, 46(4): 106-112.   doi: 10.12265/j.gnss.2021011701
[Abstract](50) [FullText HTML](33) [PDF 784KB](10)
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Carrier numerically controlled oscillator (NCO) is a key part of the navigation receiver to strip the carrier of the received signal. In the digital signal processing module, the numerically controlled oscillator quantizes the amplitude and frequency of the local carrier signal through the quantization width and addressing word. The local carrier is designed by the bit width and depth of the memory data. Under the dynamic range of given input signal/interference, this paper optimizes the design of the quantization width and addressing length of the read-only memory (ROM) in the NCO according to the characteristics of the local carrier, adapting it to the actual engineering requirement, which avoids the redundancy of local carrier storage while ensuring the performance of signal-to-noise ratio (SNR) and frequency accuracy. The experimental results show that designing the optimal quantization width and addressing word of the navigation receiver local carrier based on the requirements can ensure the digital down-conversion SNR ratio loss less than 0.1 dB, the relative error of the actual output frequency of the local carrier less than 0.1%, and the optimal quantization width and addressing word less than the value before optimization. The storage resource occupancy rate was reduced, and the adaptability of the local carrier signal under dynamic signals and interference was effectively improved.
Modeling and analysis of the weighted mean temperature used reanalysis meteorological data in Ningxia
LI Xiao, QI Feng
2021, 46(4): 113-116.   doi: 10.12265/j.gnss.2021031801
[Abstract](37) [FullText HTML](29) [PDF 887KB](9)
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The weighted mean temperature is an important parameter in Global Navigation Satellite System (GNSS) meteorology. A new statistical grid model is established by using the reanalysis meteorological data of 2017 in Ningxia. The comparison shows that the new model is more consistent with the actual value than the results of general model. The analysis shows that in order to meet the requirement of high accuracy. It is necessary to establish a suitable model by using the historical meteorological data of the local area.
Indoor fingerprint localization method based on FDE-IRF
ZHANG Wentao, WU Fei, ZHU Hai, TONG Yanhui, LU Wenxia
2021, 46(4): 117-126.   doi: 10.12265/j.gnss.2021030102
[Abstract](36) [FullText HTML](17) [PDF 3522KB](3)
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Aiming at the problems of heary work during establishment of traditional fingerprint database and the large matching error of the traditional random forest, an improved random forest localization method was proposed based on automatic fingerprint database expansion (FDE-IRF) to enhance the efficiency of fingerprint database construction and the accuracy of fingerprint matching. This method improved the traditional all sampling method to construct fingerprint database and the traditional random forest regression positioning method. The combination of sparse sampling fingerprint data of multiple time periods and Kriging interpolation method to complete unsampled fingerprint points improves the efficiency of database construction and gets a strong representative fingerprint database. At the same time, the decision tree weighting strategy is used to improve the average voting method in the traditional random forest, and the data out of bag is used to evaluate the prediction error of the decision tree and assign the corresponding weight, which improves the regression accuracy of the algorithm. The experimental results shows that the average positioning error of the proposed method is 1.26 m, which is at least 14.3% lower than that of similar methods, and verifies the accuracy and effectiveness of the proposed method.
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](936) [PDF 1536KB](400)
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  Dynamic Positioning Accuracy Test and Analysis of BeiDou Satellite Navigation System
ZHANG Fengzhao, LIU Ruihua, NI Yude, WANG Ying
2018, 43(1): 43-48.   doi: 0.13442/j.gnss.1008-9268.2018.01.008
[Abstract](760) [PDF 1895KB](219)
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Accuracy analysis of BDS-2/BDS-3 standard point positioning
FANG Xinqi, FAN Lei
2020, 45(1): 19-25.   doi: DOI:10.13442/j.gnss.1008-9268.2020.01.003
[Abstract](269) [PDF 750KB](101)
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Overview of Satellite Navigation Spoofing Signal Detection Technology
ZHANG Xin
2018, 43(6): 1-7.   doi: doi:10.13442/j.gnss.1008-9268.2018.06.001
[Abstract](583) [PDF 93258KB](158)
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A New Method of NMEA0813 Protocol Parsing
LIU Fushan, GUO Chengjun, JIA Zhendong
2017, 42(1): 70-73.   doi: 10.13442/j.gnss.1008-9268.2017.01.014
[Abstract](343) [PDF 476KB](85)
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  Performance Analysis of GPS/BDS/GALILEO Multi-system Combination Pseudo-range Point Positioning
JIA Xue, XU Wei
2017, 42(6): 16-23.   doi: 10.13442/j.gnss.1008-9268.2017.06.003
[Abstract](474) [PDF 2113KB](82)
摘要:
Precise Point Positioning Based on the RTKLIB and ]the Analysis of Result
PAN Jundao, WEI Zhaochuan, YANG Ke
2017, 42(1): 95-99.   doi: 10.13442/j.gnss.1008-9268.2017.01.019
[Abstract](564) [PDF 559KB](103)
摘要:
Test and Analysis of GPS/BDS/GLONASS Combined Pseudo range Point Positioning Performance
YAN Chao, YU Xuexiang, XU Wei, ZHANG Guanghan
2017, 42(2): 25-31.   doi: doi:10.13442/j.gnss.1008-9268.2017.02.006
[Abstract](318) [PDF 739KB](74)
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Precision Analysis of Single Point Positioning Model with GPS/GLONASS/BDS
WANG TAO
2017, 42(3): 32-37.   doi: 10.13442/j.gnss.1008-9268.2017.03.007
[Abstract](430) [PDF 618KB](47)
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Research on the Strategy of American GPS Modernization
WANG Xiaoni, ZHAO Zizheng, HAN Chao
2017, 42(1): 100-103.   doi: 10.13442/j.gnss.1008-9268.2017.01.020
[Abstract](180) [PDF 403KB](79)
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  Research Progress and Prospect of PPP/INS Integration System
WANG Haoyuan, SUN Fuping, XIAO Kai
2017, 42(5): 53-58.   doi: 10.13442/j.gnss.1008-9268.2017.05.011
[Abstract](724) [PDF 778KB](29)
Abstract:
With the construction of GNSS multi-system, precise point positioning (PPP) technology is developing in the direction of real-time and ambiguity-fixed solution. The PPP/INS integration system has a wide application prospect in the navigation and surveying field, since the convenience of not laying base station. In this paper, the contributions of GNSS multi-system, PPP ambiguity fixing, INS-aided to the PPP/INS integration system are systematically summarized. And the progresses of filtering method, smoothing algorithm and stochastic model establishment in integration system are generalized. The development trend of the PPP/INS integration system is discussed.
A novel engineering implementation technique for acquiring B1C signal in the BeiDou-3 receiver
YAN Shulin, DING Chao
2019, 44(1): 1-9.   doi: DOI:10.13442/j.gnss.1008-9268.2019.01.001
[Abstract](717) [PDF 1077KB](32)
Abstract:
The modern signals of the Chinese BeiDou-3 navigation system bring new features compared to the previous civilian signals, such as longer spreading code, involving secondary code, new modulation technique (i.e. Binary Offset Carrier BOC), data/pilot channels and so on. These innovations are able to enhance the signal acquisition robustness, but they also require specific acquisition techniques to handle the large data stream, deal with the problem of sign transition and side peaks caused by the secondary code and the BOC modulation respectively. This paper proposes a novel two-stage acquisition technique for realizing efficient acquisition of the B1C signal in the engineering implementation of the modern receiver. The first stage employs an extended parallelized Averaging Correlation (AC) search structure, which can cope with the sign transition problem, to coarsely capture the signal with high efficiency. At the second stage, a fine-search process is completed within a reduced searching range to provide high precision result. The involving of the later stage aims to avoid the side peaks effect in the tracking stage that can easily cause a false lock. In addition, both of the single and channel combining acquisition techniques are introduced, which give designers an option of implementing the acquisition with higher sensitivity but more resources. The experiment results demonstrate that the proposed method allows to use much cheaper FFT blocks and enables fast acquisition by parallel process. The proposed method can reduce the number of multiplications by at least 61% when the sampling frequency is over 50 MHz while providing quite similar acquisition precisions with the conventional method.
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](936) [PDF 1536KB](39)
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.
Performance Analysis Joint of GPS/GLONASS/Galileo Precise Point Positioning Under Occlusion Condition
TIAN Xiancai, ZHAO Xingwang, XU Miaoqiang
2018, 43(6): 8-13.   doi: doi:10.13442/j.gnss.1008-9268.2018.06.002
[Abstract](634) [PDF 62945KB](38)
Abstract:
For poor precision single point positioning performance of single GPS system under Occlusion Condition,to improve performance of precision single point positioning cross multisystem in this paper, By setting different Elevation mask angle, the environment around the city is divided into normal environment, general occlusion and heavy occlusion. Using GPS, GPS/GLONASS, GPS/Galileo, GPS/GLONASS/Galileo different modes respectively, the static PPP simulation experiments were carried out on four continuously operating reference stations in hong kong under the environment. the results show that multisystem combination can effectively remedy the shortage of satellites in the occlusion environment around the city, and the PPP performance of GPS/GLONASS, GPS/Galileo, GPS/GLONASS/Galileo combination is improved to varying degrees compared with that of a single GPS system.

Fog positioning and its applications
SHI Chuang, GU Shengfeng, JING Guifei, GENG Jianghui, LOU Yidong, TANG Weiming
2019, 44(5): 1-9.   doi: DOI:10.13442/j.gnss.1008-9268.2019.05.001
[Abstract](754) [PDF 1146KB](34)
Abstract:
With the development of GNSS, the LBS (Location Based Service) has been popularized rapidly. Meanwhile, people’s demand for PNT service with high reliability, high credibility and high precision is increasingly urgent. PNT is a system which integrates multi-technology and multilevel systems. Focusing on the optimization of PNT service, domestic and overseas scholars have put forward several new architectures and technical systems such as All Source Positioning and Navigation, Resilient PNT and Cloud Positioning. This study states, that with heterogeneous positioning resources which are capable in communication, calculation, storing, positioning and sensing as infrastructure construction, PNT service with high reliability, high credibility and high precision can be realized by intelligent management and scheduling of heterogeneous positioning resources distributed in different geolocations. Further, the definitions of Fog Positioning and Omnipresent Positioning and Navigation are given. It is argued that the definition of Fog Positioning is evolved from distributed computing architecture and emphasizes the architecture for PNT service. While the definition of Omnipresent Positioning and Navigation is evolved from the development of positioning technology and emphasizes the ability to realize omnipresent positioning by collaborative fusion processing of omnipresent positioning resources. On this basis, by comparing Fog Positioning with Cloud Positioning, this study points out that Fog Positioning is the extension of Cloud Positioning towards the user side and the omnipresent realization of positioning resources. Meanwhile, Fog Positioning is one kind of dynamic and elastic cloud, so Fog Positioning can be seen as a PNT architecture with the property of elasticity. Omnipresent positioning is an important target of PNT architecture, and Fog Positioning gives the potential means for this target, e.g., Omnipresent Positioning and Navigation. At last, this contribution analysis the basic service mode for Fog Positioning or Omnipresent Positioning and Navigation under the city environment and indoor environment.

Bimonthly, Established 1976

Sponsored by:China Institute of Radio Transmission

Competent Authorities:China Electronics Technology Group Corporation

ISSN 1008-9268

CN 41-1317/TN