全球定位系统

2021 Vol. 46, No. 3

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2021, (3): 1-2.

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2021, 46(3): 1-1.

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2021, 46(3): 1-1.

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Research on a priori and posterior weighting methods for Multi-GNSS combined single point positioning

ZHANG Zhehao, PAN Lin

2021, 46(3): 1-6. doi: 10.12265/j.gnss.2021010401

[Abstract](712) [FullText HTML] (288) [PDF 830KB](64)

Abstract:
When using multi-system code observations to conduct the pseudo range single point positioning, a reasonable stochastic model needs to be determined. In this paper, the datasets from ten multi-system stations MGEX(Multi-GNSS Experiment) on seven consecutive days are selected to compare the positioning performance of pseudo range single point positioning with the elevation-dependent model and the user equivalent range error (UERE) model, as well as the posterior Helmert variance component estimation model based on the two a priori models. The observations from the four Global Navigation Satellite Systems (GNSS) are divided into five groups. The results show that the positioning accuracy can be improved when adopting the Helmert variance component estimation model. The positioning accuracy of the elevation-dependent model is better than that of the UERE model. The Helmert variance component estimation model based on the elevation-dependent weighting strategy achieves the best positioning performance.

Adaptive sliding mode heading control of unmanned semi-submersible surveying vehicle

WU Di, HU Gaoling, LU Xingyi, YE Jiemin, ZHANG Lizhen

2021, 46(3): 7-14. doi: 10.12265/j.gnss.2021011501

[Abstract](561) [FullText HTML] (182) [PDF 1639KB](28)

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The ocean is a strategic important for the national high-quality development, and marine monitoring is an important way to understand and develop the ocean. With the continuous implementation of Marine power strategy such as "One Belt And One Road", higher requirements are put forward for Marine surveying equipment. Therefore, using the combined GPS/BDS system and electronic compass to provide high-precision position and heading information, and equipped with monitoring devices, the new unmanned semi-submersible vehicle is applied to marine environmental monitoring. Aiming at the influence of uncertain model parameters and environmental disturbance on the reliability and stability of the heading monitoring of unmanned semi-submersible vehicle, an adaptive sliding mode control (ASMC) method was designed based on the strong robustness of sliding mode control (SMC) and the high adaptability of adaptive control. Theoretical analysis and simulation experiments show that the ASMC is feasible and effective, and has better adaptability and robustness than the traditional proportional plus denriva tive (PD) control, and the system has good transient performance and stability. The designed adaptive sliding mode control method is applied to actual marine monitoring, and the test results show that the control effect is stable, the surveying data is real and reliable, and the surveying efficiency is improved.

Refined stochastic model of combining elevation angle and SNR and its impact on precise point positioning in high latitude areas

LYU Minghui, LI Wei, ZHANG Baocheng, CHAI Yanju

2021, 46(3): 15-23, 53. doi: 10.12265/j.gnss.2020122101

[Abstract](625) [FullText HTML] (300) [PDF 1044KB](98)

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Principal component analysis method is used to determine the contribution of elevation angle and signal to noise ratio (SNR) in observation noise, and a refined Global Navigation Satellite System (GNSS) stochastic model is established based on the analysis results. The performance of the refined stochastic model is verified by using precision point positioning (PPP). It shows that the refined stochastic model leads to better positioning results in high latitude areas than traditional model that only takes into account elevation angle or SNR. The refined stochastic model is about 30% more accurate than elevation angle model, and about 20% better than SNR model. The accuracy of refined stochastic model improves most obvious in the zenith direction, and the improvements are about 38% and 24% with respect to the results of elevation angle model and SNR model, respectively. This study indicates that our new refined stochastic model is advantage to high-precision positioning accuracy in high latitude areas.

Reduced-dynamic and kinematic orbit determination of Jason-3 based on satellite-borne GPS data

GUO Hengyang, GUO Jinyun, YANG Zhouming, QI Linhu, ZHAO Chunmei

2021, 46(3): 24-32. doi: 10.12265/j.gnss.2021022301

[Abstract](703) [FullText HTML] (413) [PDF 985KB](91)

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The satellite-borne GPS data are used to determine precise orbit of Jason-3 satellite with the reduced-dynamic method and the kinematic method. The orbital accuracy is assessed by the carrier phase residual analysis, overlapping orbit comparison, comparison with reference orbit and satellite laser ranging (SLR) checks. The result show that the variation range of phase residuals for reduced-dynamic orbit is 0.7 cmto 0.8 cm, the variation range of phase residuals for kinematic orbit is 0.50 cm to 0.55 cm. The radial root mean square (RMS) error of the reduced-dynamic overlapping orbits is 0.32 cm, and the same error of the kinematic overlapping orbits is 1.12 cm. Compared with the reference orbits released by international DORIS service(IDS), the radial RMS of reduced-dynamic orbits is about 1.47 cm, and the radial RMS of kinematic orbits is about 4.36 cm. Results of SLR checks show that the reduced-dynamic orbital accuracy is better than 2.1 cm, and the kinematic orbital accuracy is better than 3.3 cm. The experimental results proved that the accuracy of both reduced-dynamic and kinematic orbits of Jason-3 altimetry satellite were at centimeter level, which could meet the accuracy requirements of satellite orbit.

TEQC data quality visual analysis software based on Python design

WU Jiajie, WANG Ting, HUANG Er’shuang

2021, 46(3): 33-38. doi: 10.12265/j.gnss.2021012701

[Abstract](1481) [FullText HTML] (502) [PDF 1754KB](113)

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The quality of the Global Navigation Satellite System (GNSS) observation data directly affects the accuracy and reliability of GNSS positioning. In order to obtain observation data of good quality, users usually use TEQC software to preprocess the data. Because TEQC is a command line software based on DOS system, it has some defects such as poor interaction and weak visualization function. At present, although there are third-party drawing tools such as QCVIEW, CF2PS and QC2SKY that can realize the drawing function, these tools no longer support the Compact3 format result files generated by TEQC after March 15, 2013. Therefore, this paper uses Python language to visually design the quality inspection module of TEQC, and compiles a quality visualization software TPP (TEQC Plot of Python). The software performance test and analysis show that the software can reflect the satellite quality check index at different time, azimuth and altitude angle.

Short-term prediction and stability analysis of BDS-3 satellite clocks bias

YA Shaoshuai, ZHAO Xingwang, HU Haojie, LIU Chao, CHEN Jian

2021, 46(3): 39-46. doi: 10.12265/j.gnss.2020120703

[Abstract](558) [FullText HTML] (298) [PDF 5687KB](39)

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Aiming at the short-term prediction of the BeiDou-3 Navigation Satellite System (BDS-3) satellite clock, based on the analysis of the frequency stability of the satellite atomic clock, and autoregressive integrated moving average, grey model, linear polynomial and quadratic polynomial four kinds of clock bias prediction models are used to fit and predict based on 30 days of data. The experimental results show that: 1) Compared with BeiDou-2 Navigation Satellite System (BDS-2), the BDS-3 atomic clock has higher stability, among which the thousand-second stability, ten-thousand-second stability and daily stability of the BDS-3 hydrogen clock have reached 4.2×10⁻¹⁴, 1.89×10⁻¹⁴ and 4.14×10⁻¹⁵ respectively; 2) The prediction stability of the BDS-3 hydrogen clock and the BDS-3 new rubidium clock is significantly improved compared to the BDS-2 rubidium clock, and the prediction accuracy of the BDS-3 hydrogen clock is the best, reaching 0.12 ns, 0.18 ns, 0.30 ns at 3 h, 6 h and 12 h respectively; 3) Among the four models, the time series model has the highest forecast accuracy, with accuracy of 0.26 ns, 0.47 ns and 0.96 ns at 3 h, 6 h and 12 h, respectively.

Application research of GPS PPP in railway scene based on uncalibrated phase delay paramteters

SONG Yiqiao, LIN Chunfeng, ZHAO Bing, GUO Gang, GAO Ke

2021, 46(3): 47-53. doi: 10.12265/j.gnss.2021121002

[Abstract](602) [FullText HTML] (168) [PDF 1649KB](21)

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The Global Navigation Satellite System (GNSS) reference stations along the railway in complex and dangerous areas are relatively sparse. How to obtain the high precision position information for the stations under this scenario is an important problem. Taking the single GPS system for instance, the satellite tracking number and the position dilution of precision (PDOP) are evaluation, the reliability and usability of the observation are carried out and the research of enhanced precise point positioning (PPP) technology is implemented by using 7 GNSS stations (14 observation periods) along the railway. The results show that: 1) the average numbers of tracking satellites is about 5.14 to 9.07 and the average PDOP is about 2.19 to 5.72 in all time periods, which has high localization availability; 2) Enhanced PPP can further improve the accuracy of PPP in railway environment. When the observation time is about 90 min, the positioning solution can be better than 10 cm and 15 cm in horizontal and vertical direction, respectively. Compared with float solution, the positioning accuracy in 3D direction can be improved by about 35.43%. This study can provide high-precision position information in the survey and construction stage for complex railway scene.

The application of improved Sage-Husa algorithm in aircraft integrated navigation

SUN Shuguang, WEN Qixin

2021, 46(3): 54-60. doi: 10.12265/j.gnss.2021012401

[Abstract](519) [FullText HTML] (288) [PDF 1491KB](28)

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Aiming at the airborne integrated navigation system, considering the air pressure altitude in different flight stages, an improved Sage-Husa adaptive filtering algorithm is proposed to improve the positioning accuracy of the integrated navigation system. This algorithm calculates and corrects the adjustment factor of filter anomaly determination in real time by introducing air pressure altitude to meet the filtering requirements of different flight stages of the aircraft. Through strap-down inertial navigation system (SINS), global navigation satellite system (GNSS) positioning error characteristics simulation, Kalman filter combination algorithm simulation, and improved Sage-Husa The adaptive filtering algorithm is simulated, and the relevant results are compared and verified. The simulation results show that improving the Sage-Husa adaptive filtering can improve the adaptiveness of the filtering, reduce the positioning error of the integrated navigation system, and achieve better results.

A optimized fusion zenith tropospheric delay model-FZTD

QUAN Xuezhen, ZHANG Jie, SONG Xiurong, YANG Bin

2021, 46(3): 61-65. doi: 10.12265/j.gnss.2020120701

[Abstract](462) [FullText HTML] (226) [PDF 731KB](22)

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Tropospheric delay is one of the main error sources that affect the accuracy of Global Navigation Satellite System (GNSS) navigation and positioning. One effective way to weaken the influence of tropospheric delay is the model correction method. This paper has proposed a simple and accurate fusion tropospheric delay model (FZTD) by combining the simplicity of the UNB3 model and the high-precision characteristics of the GPT2w model. The accuracy of the purposed model was verified by using the International GNSS Service (IGS) troposphere zenith delay (ZTD) data over 2011—2015. The results show that root mean square (RMS) and bias values of the FZTD model are 4.4 cm and −0.3 cm, respectively, which are smaller than the traditional models UNB3m (RMS: 5.1 cm, bias: 1.1 cm) and EGNOS (RMS: 5.1 cm, bias: 0.3 cm). Its global accuracy has increased by 14%, and the improvement is particularly obvious in the southern hemisphere, especially in the Antarctic region, the accuracy has increased by nearly 3 times. The FZTD model makes up for the shortcomings of the traditional models that there are large differences in accuracy between the northern and southern hemispheres. The total meteorological parameters of the new model are only 120, which are drastically reduced compared to the GPT2w model, which makes it possible to be hardwired in the GNSS receivers.

Performance analysis of BDS/GNSS precision point positioning

YIN Haibo, GUO Hang, LUO Xiaowen

2021, 46(3): 66-71. doi: 10.12265/j.gnss.2020121501

[Abstract](589) [FullText HTML] (176) [PDF 1175KB](67)

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With the success of the global networking of the BeiDou Navigation Satellite System (BDS), the application research based on the BDS is in full swing, especially the multi-frequency and multi-mode fusion positioning including BDS is becoming the focus of research. This article uses BDS (BDS-3), GPS, GLONASS, and Galileo observation data from multiple stations in the MGEX (Multi-GNSS Experiment), based on RTKLIB open source code, and performs the precision point positioning experiment of the three combined systems BDS/GPS, BDS/GLONASS, and BDS/Galileo on the Visual Studio 2017 platform. The positioning performance of the three combined systems is compared and analyzed from static PPP, dynamic PPP, number of visible satellites, and attenuation of precision (DOP). The experimental results show that the BDS/GPS combined system has the largest number of visible satellites and the smallest DOP value. The accuracy of the three directions after static PPP convergence is better than 6 cm. Whether it is static or dynamic, its positioning performance is the best. The dynamic precise point positioning (PPP) positioning jitter of the BDS/GLONASS and BDS/Galileo combined system is relatively large. It can be seen that the number of satellites is smaller than the BDS/GPS combined system, and the convergence time is longer. The dynamic PPP positioning performance of the two is also worse than that of the BDS/GPS combined system.

Design and implementation of closed tracking loop of navigation receiver based on SoC

XUE Zhiqin, LIU Kun, LI Liguang

2021, 46(3): 72-77, 103. doi: 10.12265/j.gnss.2020121402

[Abstract](505) [FullText HTML] (198) [PDF 1366KB](34)

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The traditional satellite navigation receiver is based on FPGA+DSP architecture. Under this architecture, the tracking module is in an open-loop processing mode. It has the problems of poor real-time performance and poor reliability. At the same time, a large amount of data communication between FPGA and DSP has led to an increase in IO resources and power consumption. Based on the SoC architecture, a closed-loop tracking loop scheme for satellite navigation receiver is proposed in this paper. The entire tracking process is processed in a closed loop within the FPGA. This effectively solves the problems of open-loop tracking, and greatly reduces the amount of data communication between FPGA and CPU. In addition, all tracking channels share a tracking loop processing module through time division multiplexing, which effectively saves hardware resources and reduces costs. This paper lays a foundation for the design and development of miniaturized, low-power navigation chips.

Seamless link method of indoor and outdoor transition zone for Beidou /UWB combination positioning

CAI Yihao, WANG Qianxin, ZHU Meiguo, CHEN Chen, HU Yongfeng

2021, 46(3): 78-84. doi: 10.12265/j.gnss.2021021901

[Abstract](1035) [FullText HTML] (174) [PDF 1209KB](69)

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Indoor and outdoor seamless navigation and positioning is the cornerstone of everything is interconnected, and it has broad market prospects and application value. However, there are still many knotty problems for the seamless integrated navigation of indoor and outdoor transition area. In order to solve those problems, this article improves the indoor and outdoor seamless linking method of Beidou satellite navigation system Ultra-wideband (BDS/UWB) combined positioning from three aspects: The first is to propose an indoor beacon absolute positioning method based on internal and external citation methods, which to solve the problem of the coordinate reference unification of indoor and outdoor positioning results; the second is to propose an optimal layout scheme of indoor beacon based on PDOP stable change, which to improve the positioning accuracy and beacon availability in the transition area; the third is to introduce an adaptive weight factor to solve the reasonable weighting problem of observations of BDS/ UWB combined positioning. It is verified through specific experiments: 1) using the indoor beacon absolute positioning method based on indoor guidance and outdoor guidance method, it is possible to achieve the indoor and outdoor coordinate reference unification, which significantly improves the convenience of users; 2) the optimal layout scheme of indoor beacon can effectively improve the positioning accuracy of the transition area. compared with and without UWB beacons, the BDS/UWB combined positioning accuracy can be improved by at least 355%; 3) the adaptive weight factor can adjust the observation weight ratio of different time and different types in real-time, and it enhances the efficiency of observation information utilization. Compared with BDS in open area, its positioning accuracy can be improved by at least 22.5%.

Space alignment of ground-based augmentation system and instrument landing system

NI Yude, ZHANG Zhennan

2021, 46(3): 85-93. doi: 10.12265/j.gnss.2021011101

[Abstract](719) [FullText HTML] (263) [PDF 3569KB](30)

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The benchmark of navigation information output by Ground-Based Augmentation System (GBAS) and instrument landing system(ILS) is different. If the data fusion technology is to be used to realize the combination and sharing of the two, the first problem is to align the different navigation information in space. The deviation indication methods of GBAS and ILS are studied and the spatial alignment algorithms of GBAS and ILS are deduced in detail. The X-Plane flight data interaction and analysis system is developed, and the system is used to collect flight data from X-Plane to simulate and verify the given space alignment algorithm. As show in the simulation results, the navigation information of GBAS and ILS can be effectively converted to the unified reference by the proposed space alignment algorithm. Theoretical support for the data fusion research of GBAS and ILS is provided.

A Gaussian Sum Filter-based indoor localization algorithm using bluetooth beacons

YAN Zhi

2021, 46(3): 94-98. doi: 10.12265/j.gnss.2020110602

[Abstract](622) [FullText HTML] (171) [PDF 892KB](53)

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High precision indoor localization is the basis of location based service in Internet of Thing. The received signal strength indicator (RSSI) values of bluetooth low energy (BLE) can be used to do analysis and computation in location system. Therefore, Gaussian sum filter-based indoor localization used bluetooth beacons (GSF-IL) is proposed in this paper. Considering the multipath fading and fluctuation of indoor environmental signals, the Gaussian sum filter (GSF) is used to process the RSSI measurement value, so that the RSSI value has non-Gaussian characteristics, and the Wasserstein distance (WD) is used to reduce the component number of the GSF model to a single Gaussian component. Simulation results show that the proposed GSF-IL algorithm can modify the original RSSI value and make use of the positioning accuracy.

Accuracy analysis of Galileo dual-frequency and triple-frequency short baseline solution under the condition of non-combined model

XU Yanan, LIU Shun

2021, 46(3): 99-103. doi: 10.12265/j.gnss.2021010801

[Abstract](510) [FullText HTML] (159) [PDF 1184KB](21)

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Galileo system is one of the commonly used positioning systems at present. This paper uses self-edited software to carry out a dual-frequency and triple-frequency short baseline solution experiment of Galileo system under the condition of non-combined model. Research has found that for a 9 km short baseline, the Galileo dual-frequency short baseline solution under the non-combined model has a horizontal accuracy better than 5 cm, and an elevation accuracy better than 10 cm. The triple-frequency combined solution accuracy is significantly improved compared with that of dual-frequency. The horizontal accuracy is better than 3 cm. The elevation accuracy is better than 4 cm.

Analysis of positioning performance of BDS-3/GPS in shadow environment

YANG Yi, HU Hong, XIE Xuefeng, TIAN Xiangyong

2021, 46(3): 104-110. doi: 10.12265/j.gnss.2020120301

[Abstract](873) [FullText HTML] (319) [PDF 1475KB](89)

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In areas where GNSS signals are easily sheltered, the number of visible satellites in a single navigation system is small, and the positioning performance is not ideal or even difficult to meet the requrements of positioning needs. In this paper, the improvement of BDS-3's positioning performance in shadow environments is analyzed in different area. Based on the observation data of MGEX monitoring stations in different regions of the world, three modes of GPS, BDS-3, and BDS-3/GPS combined positioning are used to perform pseudo-range single-point positioning under different simulated shadow environments, and the number of visible satellites in each mode is analyzed, together with epoch utilization, GDOP value and positioning accuracy. The results show that in the northern hemisphere, compared to shadow in other direction, the GPS mode has the highest positioning stability and accuracy in the south of low latitudes, and the highest positioning stability and accuracy in the north of the middle and high latitudes. BDS-3 and BDS-3/GPS mode has the same positioning accuracy in all directions in low latitude areas. In mid-latitude and mid-high latitude areas, the accuracy of north shadowed is significantly better when shadow is in the north direction than that of other directions. The BDS-3/GPS combined positioning mode greatly increases the number of available satellites, improves the epoch utilization rate, improves the satellite spatial geometry, and reduces the GDOP value, which is significantly better than a single system in stability and positioning accuracy.

Application of BDS in an integrated intelligent safety helmet

CAO Yu, TANG Xiaobo, SONG Yuze, WANG Ning, LU Hongjiang

2021, 46(3): 111-115. doi: 10.12265/j.gnss.2021011402

[Abstract](521) [FullText HTML] (427) [PDF 1023KB](40)

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The demand for intelligent safety helmets is applied at engineering sites, and has been valued by domestic and international users as automated instruments become more and more popular. BeiDou satellite positioning system (BDS) development technology has become the new highland of science and technology innovation in today's world. In order to accelerate the pace of commercial production of integrated intelligent safety helmet, it is urgent to strengthen the long term monitoring of the environment the operator works. This paper designs a system based on BDS, which can provide operator's environment monitoring and assessment. By showing carbon dioxide (CO) concentration, temperature, humidity, and the actual situation of the environment in which the operator works, the targeting and the monitoring data transmission of the operator's working condition can be realized. Also, real-time safety assessment of the working environment under different working conditions, trajectory tracking and disaster warning functions can be accomplished.

Design of SCA standard conformance test for hardware abstraction layer based on a satellite navigation receiver

LUO Wen

2021, 46(3): 116-122. doi: 10.12265/j.gnss.2020121702

[Abstract](626) [FullText HTML] (220) [PDF 924KB](31)

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Aiming at the portability of satellite navigation signal waveform on different hardware platforms, after introducing the Hardware Abstraction Layer into the system, the unification of management and communication standardization between components in different computing units are realized. In order to test the conformity of modem hardware abstraction layer (MHAL)and prevent different research units from developing incompatible software communications architect (SCA) communication equipment, a Satellite navigation receiver is taken as an example. MHAL test method based on specific hardware platform is explained, and a set of test cases is designed. By using CORBA (Common Object Request Broker Architecture) middleware Tao and software function dynamic configuration method, the test case set can shield the differences between the tested devices, improve the universality, compatibility and test efficiency of test cases. And users can complete the automatic test with one key operation on the PC. The results show that the test suite can fully verify the ability of hardware abstraction layer to realize data transmission and meet the conformity of SCA, so as to meet the needs of users