scholarly journals Integration of multi-constellation GNSS precise point positioning and MEMS-based inertial system for precise applications

2021 ◽  
Author(s):  
Mahmoud Abd Rabbou
Keyword(s):  
Precise Point Positioning ◽  
Low Cost ◽  
Satellite System ◽  
Integrated System ◽  
Inertial System ◽  
Integrated Navigation ◽  
Positioning Accuracy ◽  
Phase Measurements ◽  
Point Positioning ◽  
Inertial Measurements

This dissertation develops a low-cost integrated navigation system, which integrates multi-constellation global navigation satellite system (GNSS) precise point positioning (PPP) with a low-cost micro-electro-mechanical sensor (MEMS)-based inertial system for precise applications. Both undifferenced and between-satellite single-difference (BSSD) ionosphere-free linear combinations of pseudorange and carrier phase measurements from three GNSS constellations, namely GPS, GLONASS and Galileo, are processed. An improved version of the PF, the unscented particle filter (UPF), which combines the UKF and the PF, is developed to merge the corrected GNSS satellite difference observations and inertial measurements and estimate inertial measurements biases and errors. The performance of the proposed integrated system is analyzed using real test scenarios. A tightly coupled GPS PPP/MEMS-based inertial system is first developed using EKF, which shows that decimeter-level positioning accuracy is achievable with both undifferenced and BSSD modes. However, in general, better positioning precision is obtained when BSSD linear combination is used. During GPS outages, the integrated system shows submeter-level accuracy in most cases when a 60-second outage is introduced. However, the positioning accuracy is improved to a few decimeter- and decimeter-level accuracy when 30- and 10-second GPS outages are introduced, respectively. The use of UPF, on the other hand, reduces the number of samples significantly, in comparison with the traditional PF. Additionally, in comparison with EKF, the use of UPF improves the positioning accuracy during the 60-second GPS outages by 14%, 13% and 15% in latitude, longitude and altitude, respectively. The addition of GLONASS and Galileo observations to the developed integrated system shows that decimeter- to centimeter-level positioning accuracy is achievable when the GNSS measurement updates are available. In comparison with the GPS-based integrated system, the multi-constellation GNSS PPP/MEMS-based inertial system improves the latitude, longitude and altitude components precision by 24%, 41% and 41%, respectively. In addition, the use of BSSD mode improves the precision of the latitude, longitude and altitude components by 23%, 15% and 13%, respectively, in comparison with the undifferenced mode. During complete GNSS outages, the developed integrated system continues to achieve decimeter-level accuracy for up to 30 seconds, while it achieves submeter-level accuracy when a 60-second outage is introduced.

scholarly journals Integration of multi-constellation GNSS precise point positioning and MEMS-based inertial system for precise applications

2021 ◽  
Author(s):  
Mahmoud Abd Rabbou
Keyword(s):  
Precise Point Positioning ◽  
Low Cost ◽  
Satellite System ◽  
Integrated System ◽  
Inertial System ◽  
Integrated Navigation ◽  
Positioning Accuracy ◽  
Phase Measurements ◽  
Point Positioning ◽  
Inertial Measurements

This dissertation develops a low-cost integrated navigation system, which integrates multi-constellation global navigation satellite system (GNSS) precise point positioning (PPP) with a low-cost micro-electro-mechanical sensor (MEMS)-based inertial system for precise applications. Both undifferenced and between-satellite single-difference (BSSD) ionosphere-free linear combinations of pseudorange and carrier phase measurements from three GNSS constellations, namely GPS, GLONASS and Galileo, are processed. An improved version of the PF, the unscented particle filter (UPF), which combines the UKF and the PF, is developed to merge the corrected GNSS satellite difference observations and inertial measurements and estimate inertial measurements biases and errors. The performance of the proposed integrated system is analyzed using real test scenarios. A tightly coupled GPS PPP/MEMS-based inertial system is first developed using EKF, which shows that decimeter-level positioning accuracy is achievable with both undifferenced and BSSD modes. However, in general, better positioning precision is obtained when BSSD linear combination is used. During GPS outages, the integrated system shows submeter-level accuracy in most cases when a 60-second outage is introduced. However, the positioning accuracy is improved to a few decimeter- and decimeter-level accuracy when 30- and 10-second GPS outages are introduced, respectively. The use of UPF, on the other hand, reduces the number of samples significantly, in comparison with the traditional PF. Additionally, in comparison with EKF, the use of UPF improves the positioning accuracy during the 60-second GPS outages by 14%, 13% and 15% in latitude, longitude and altitude, respectively. The addition of GLONASS and Galileo observations to the developed integrated system shows that decimeter- to centimeter-level positioning accuracy is achievable when the GNSS measurement updates are available. In comparison with the GPS-based integrated system, the multi-constellation GNSS PPP/MEMS-based inertial system improves the latitude, longitude and altitude components precision by 24%, 41% and 41%, respectively. In addition, the use of BSSD mode improves the precision of the latitude, longitude and altitude components by 23%, 15% and 13%, respectively, in comparison with the undifferenced mode. During complete GNSS outages, the developed integrated system continues to achieve decimeter-level accuracy for up to 30 seconds, while it achieves submeter-level accuracy when a 60-second outage is introduced.

scholarly journals Single-frequency Ionosphere-free Precise Point Positioning Using Combined GPS and GLONASS Observations

2013 ◽  
Vol 66 (3) ◽  
pp. 417-434 ◽  
Author(s):  
Changsheng Cai ◽  
Zhizhao Liu ◽  
Xiaomin Luo
Keyword(s):  
Precise Point Positioning ◽  
Low Cost ◽  
Satellite Orbit ◽  
Satellite System ◽  
Convergence Time ◽  
Single Frequency ◽  
Positioning Accuracy ◽  
Clock Correction ◽  
Point Positioning ◽  
Global Navigation Satellite

Single-frequency Precise Point Positioning (PPP) using a Global Navigation Satellite System (GNSS) has been attracting increasing interest in recent years due to its low cost and large number of users. Currently, the single-frequency PPP technique is mainly implemented using GPS observations. In order to improve the positioning accuracy and reduce the convergence time, we propose the combined GPS/GLONASS Single-Frequency (GGSF) PPP approach. The approach is based on the GRoup And PHase Ionospheric Correction (GRAPHIC) to remove the ionospheric effect. The performance of the GGSF PPP was tested using both static and kinematic datasets as well as different types of precise satellite orbit and clock correction data, and compared with GPS-only and GLONASS-only PPP solutions. The results show that the GGSF PPP accuracy degrades by a few centimetres using rapid/ultra-rapid products compared with final products. For the static GGSF PPP, the position filter typically converges at 71, 33 and 59 minutes in the East, North and Up directions, respectively. The corresponding positioning accuracies are 0·057, 0·028 and 0·121 m in the East, North and Up directions. Both positioning accuracy and convergence time have been improved by approximately 30% in comparison to the results from GPS-only or GLONASS-only single-frequency PPP. A kinematic GGSF PPP test was conducted and the results illustrate even more significant benefits of increased accuracy and reliability of PPP solutions by integrating GPS and GLONASS signals.

scholarly journals Real-time GNSS precise point positioning for low-cost smart devices

GPS Solutions ◽  
2021 ◽  
Vol 25 (2) ◽  
Author(s):  
Liang Wang ◽  
Zishen Li ◽  
Ningbo Wang ◽  
Zhiyu Wang
Keyword(s):  
Carrier Phase ◽  
Measurement Errors ◽  
Precise Point Positioning ◽  
Low Cost ◽  
Smart Devices ◽  
Dual Frequency ◽  
Static Mode ◽  
Phase Measurements ◽  
Positioning Errors ◽  
Point Positioning

AbstractGlobal Navigation Satellite System raw measurements from Android smart devices make accurate positioning possible with advanced techniques, e.g., precise point positioning (PPP). To achieve the sub-meter-level positioning accuracy with low-cost smart devices, the PPP algorithm developed for geodetic receivers is adapted and an approach named Smart-PPP is proposed in this contribution. In Smart-PPP, the uncombined PPP model is applied for the unified processing of single- and dual-frequency measurements from tracked satellites. The receiver clock terms are parameterized independently for the code and carrier phase measurements of each tracking signal for handling the inconsistency between the code and carrier phases measured by smart devices. The ionospheric pseudo-observations are adopted to provide absolute constraints on the estimation of slant ionospheric delays and to strengthen the uncombined PPP model. A modified stochastic model is employed to weight code and carrier phase measurements by considering the high correlation between the measurement errors and the signal strengths for smart devices. Additionally, an application software based on the Android platform is developed for realizing Smart-PPP in smart devices. The positioning performance of Smart-PPP is validated in both static and kinematic cases. Results show that the positioning errors of Smart-PPP solutions can converge to below 1.0 m within a few minutes in static mode and the converged solutions can achieve an accuracy of about 0.2 m of root mean square (RMS) both for the east, north and up components. For the kinematic test, the RMS values of Smart-PPP positioning errors are 0.65, 0.54 and 1.09 m in the east, north and up components, respectively. Static and kinematic tests both show that the Smart-PPP solutions outperform the internal results provided by the experimental smart devices.

scholarly journals Performance Analysis of Static Precise Point Positioning Using Open-Source GAMP

2020 ◽  
Vol 55 (2) ◽  
pp. 41-60
Author(s):  
Jabir Shabbir Malik
Keyword(s):  
Performance Analysis ◽  
Open Source ◽  
Observational Data ◽  
Precise Point Positioning ◽  
Three Dimensional ◽  
Satellite System ◽  
International Gnss Service ◽  
Positioning Accuracy ◽  
Position Accuracy ◽  
Point Positioning

AbstractIn addition to Global Positioning System (GPS) constellation, the number of Global Navigation Satellite System (GLONASS) satellites is increasing; it is now possible to evaluate and analyze the position accuracy with both the GPS and GLONASS constellation. In this article, statistical analysis of static precise point positioning (PPP) using GPS-only, GLONASS-only, and combined GPS/GLONASS modes is evaluated. Observational data of 10 whole days from 10 International GNSS Service (IGS) stations are used for analysis. Position accuracy in east, north, up components, and carrier phase/code residuals is analyzed. Multi-GNSS PPP open-source package is used for the PPP performance analysis. The analysis also provides the GNSS researchers the understanding of the observational data processing algorithm. Calculation statistics reveal that standard deviation (STD) of horizontal component is 3.83, 13.80, and 3.33 cm for GPS-only, GLONASS-only, and combined GPS/GLONASS PPP solutions, respectively. Combined GPS/GLONASS PPP achieves better positioning accuracy in horizontal and three-dimensional (3D) accuracy compared with GPS-only and GLONASS-only PPP solutions. The results of the calculation show that combined GPS/GLONASS PPP improves, on an average, horizontal accuracy by 12.11% and 60.33% and 3D positioning accuracy by 10.39% and 66.78% compared with GPS-only and GLONASS-only solutions, respectively. In addition, the results also demonstrate that GPS-only solutions show an improvement of 54.23% and 62.54% compared with GLONASS-only PPP mode in horizontal and 3D components, respectively. Moreover, residuals of GLONASS ionosphere-free code observations are larger than the GPS code residuals. However, phase residuals of GPS and GLONASS phase observations are of the same magnitude.

scholarly journals Multi-GNSS Combined Precise Point Positioning Using Additional Observations with Opposite Weight for Real-Time Quality Control

2019 ◽  
Vol 11 (3) ◽  
pp. 311 ◽  
Author(s):  
Wenju Fu ◽  
Guanwen Huang ◽  
Yuanxi Zhang ◽  
Qin Zhang ◽  
Bobin Cui ◽  
...  
Keyword(s):  
Quality Control ◽  
Real Time ◽  
Precise Point Positioning ◽  
Satellite System ◽  
Convergence Time ◽  
Navigation Satellite ◽  
Positioning Accuracy ◽  
Global Navigation ◽  
Point Positioning ◽  
Global Navigation Satellite

The emergence of multiple global navigation satellite systems (multi-GNSS), including global positioning system (GPS), global navigation satellite system (GLONASS), Beidou navigation satellite system (BDS), and Galileo, brings not only great opportunities for real-time precise point positioning (PPP), but also challenges in quality control because of inevitable data anomalies. This research aims at achieving the real-time quality control of the multi-GNSS combined PPP using additional observations with opposite weight. A robust multiple-system combined PPP estimation is developed to simultaneously process observations from all the four GNSS systems as well as single, dual, or triple systems. The experiment indicates that the proposed quality control can effectively eliminate the influence of outliers on the single GPS and the multiple-system combined PPP. The analysis on the positioning accuracy and the convergence time of the proposed robust PPP is conducted based on one week’s data from 32 globally distributed stations. The positioning root mean square (RMS) error of the quad-system combined PPP is 1.2 cm, 1.0 cm, and 3.0 cm in the east, north, and upward components, respectively, with the improvements of 62.5%, 63.0%, and 55.2% compared to those of single GPS. The average convergence time of the quad-system combined PPP in the horizontal and vertical components is 12.8 min and 12.2 min, respectively, while it is 26.5 min and 23.7 min when only using single-GPS PPP. The positioning performance of the GPS, GLONASS, and BDS (GRC) combination and the GPS, GLONASS, and Galileo (GRE) combination is comparable to the GPS, GLONASS, BDS and Galileo (GRCE) combination and it is better than that of the GPS, BDS, and Galileo (GCE) combination. Compared to GPS, the improvements of the positioning accuracy of the GPS and GLONASS (GR) combination, the GPS and Galileo (GE) combination, the GPS and BDS (GC) combination in the east component are 53.1%, 43.8%, and 40.6%, respectively, while they are 55.6%, 48.1%, and 40.7% in the north component, and 47.8%, 40.3%, and 34.3% in the upward component.

scholarly journals Study on Multi-GNSS Precise Point Positioning Performance with Adverse Effects of Satellite Signals on Android Smartphone

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6447
Author(s):  
Hongyu Zhu ◽  
Linyuan Xia ◽  
Dongjin Wu ◽  
Jingchao Xia ◽  
Qianxia Li
Keyword(s):  
Adverse Effects ◽  
Precise Point Positioning ◽  
Phase Error ◽  
Three Dimensional ◽  
Satellite System ◽  
Dual Frequency ◽  
Positioning Accuracy ◽  
Noise Ratio ◽  
Point Positioning ◽  
Gnss Observations

The emergence of dual frequency global navigation satellite system (GNSS) chip actively promotes the progress of precise point positioning (PPP) technology in Android smartphones. However, some characteristics of GNSS signals on current smartphones still adversely affect the positioning accuracy of multi-GNSS PPP. In order to reduce the adverse effects on positioning, this paper takes Huawei Mate30 as the experimental object and presents the analysis of multi-GNSS observations from the aspects of carrier-to-noise ratio, cycle slip, gradual accumulation of phase error, and pseudorange residual. Accordingly, we establish a multi-GNSS PPP mathematical model that is more suitable for GNSS observations from a smartphone. The stochastic model is composed of GNSS step function variances depending on carrier-to-noise ratio, and the robust Kalman filter is applied to parameter estimation. The multi-GNSS experimental results show that the proposed PPP method can significantly reduce the effect of poor satellite signal quality on positioning accuracy. Compared with the conventional PPP model, the root mean square (RMS) of GPS/BeiDou (BDS)/GLONASS static PPP horizontal and vertical errors in the initial 10 min decreased by 23.71% and 62.06%, respectively, and the horizontal positioning accuracy reached 10 cm within 100 min. Meanwhile, the kinematic PPP maximum three-dimensional positioning error of GPS/BDS/GLONASS decreased from 16.543 to 10.317 m.

scholarly journals Compact, Low-cost GNSS Modules for Precise Point Positioning

2021 ◽  
Vol 310 ◽  
pp. 03001
Author(s):  
Anindya Bose ◽  
Somnath Mahato ◽  
Sukabya Dan ◽  
Atanu Santra
Keyword(s):  
Precise Point Positioning ◽  
Low Cost ◽  
Real Life ◽  
Cost Effective ◽  
Satellite System ◽  
Vertical Coordinate ◽  
Point Positioning ◽  
Cost Efficient ◽  
Global Navigation Satellite ◽  
Solution Accuracy

Global Navigation Satellite System (GNSS) uses Precise Point Positioning (PPP) technique to find out accurate geolocation information of any point. Generally, costly, geodetic GNSS receivers are used for PPP. This manuscript presents the results of studies on the usability of commercial, compact, cost-effective GNSS modules with commercial antennas for PPP in comparison to commonly used geodetic, costly receivers from India, which is a excellent location for GNSS use. Compact GNSS modules from two manufacturers are used in the study, and the encouraging results show the clear advantage of cost, size, and power requirements of such modules. The modules provide sub-cm horizontal solution accuracy which is very similar to those obtained using geodetic receivers, and around 20 cm accuracy in the vertical coordinate, which is slightly inferior to the results provided by the geodetic reveivers. Results of this novel study would be useful for implementing cost-efficient GNSS PPP in real life, in highly demanding geodetic applications including CORS establishment and PPP.

scholarly journals Assessment of BeiDou-3 and Multi-GNSS Precise Point Positioning Performance

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2496 ◽  
Author(s):  
Guoqiang Jiao ◽  
Shuli Song ◽  
Yulong Ge ◽  
Ke Su ◽  
Yangyang Liu
Keyword(s):  
Precise Point Positioning ◽  
Geographic Area ◽  
Satellite System ◽  
Assessment System ◽  
Convergence Time ◽  
Navigation Satellite ◽  
Positioning Accuracy ◽  
Kinematic Positioning ◽  
Global Coverage ◽  
Point Positioning

With the launch of BDS-3 and Galileo new satellites, the BeiDou navigation satellite system (BDS) has developed from the regional to global system, and the Galileo constellation will consist of 26 satellites in space. Thus, BDS, GPS, GLONASS, and Galileo all have the capability of global positioning services. It is meaningful to evaluate the ability of global precise point positioning (PPP) of the GPS, BDS, GLONASS, and Galileo. This paper mainly contributes to the assessment of BDS-2, BDS-2/BDS-3, GPS, GLONASS, and Galileo PPP with the observations that were provided by the international Global Navigation Satellite System (GNSS) Monitoring and Assessment System (iGMAS). The Position Dilution of Precision (PDOP) value was utilized to research the global coverage of GPS, BDS-2, BDS-2/BDS-3, GLONASS, and Galileo. In particular, GPS-only, BDS-2-only, BDS-2/BDS-3, GLONASS-only, Galileo-only, and multi-GNSS combined PPP solutions were analyzed to verify the capacity of the PPP performances in terms of positioning accuracy, convergence time, and zenith troposphere delay (ZTD) accuracy. In view of PDOP, the current BDS and Galileo are capable of global coverage. The BDS-2/BDS-3 and Galileo PDOP values are fairly evenly distributed around the world similar to GPS and GLONASS. The root mean square (RMS) of positioning errors for static BDS-2/BDS-3 PPP and Galileo-only PPP are 10.7, 19.5, 20.4 mm, and 6.9, 18.6, 19.6 mm, respectively, in the geographic area of the selected station, which is the same level as GPS and GLONASS. It is worth mentioning that, by adding BDS-3 observations, the positioning accuracy of static BDS PPP is improved by 17.05%, 24.42%, and 35.65%, and the convergence time is reduced by 27.15%, 27.87%, and 35.76% in three coordinate components, respectively. Similar to the static positioning, GPS, BDS-2/BDS-3, GLONASS, and Galileo have the basically same kinematic positioning accuracy. Multi-GNSS PPP significantly improves the positioning performances in both static and kinematic positioning. In terms of ZTD accuracy, the difference between GPS, BDS-2/BDS-3, GLONASS, and Galileo is less than 1 mm, and the BDS-2/BDS-3 improves ZTD accuracy by 20.48% over the BDS-2. The assessment of GPS, BDS-2, BDS-2/BDS-3, GLONASS, Galileo, and multi-GNSS global PPP performance are shown to make comments for the development of multi-GNSS integration, global precise positioning, and the construction of iGMAS.

scholarly journals Improving the Performance of Galileo Uncombined Precise Point Positioning Ambiguity Resolution Using Triple-Frequency Observations

2019 ◽  
Vol 11 (3) ◽  
pp. 341 ◽  
Author(s):  
Gen Liu ◽  
Xiaohong Zhang ◽  
Pan Li
Keyword(s):  
Ambiguity Resolution ◽  
Precise Point Positioning ◽  
Simulated Data ◽  
Satellite System ◽  
Dual Frequency ◽  
Positioning Accuracy ◽  
Processing Mode ◽  
Beidou Navigation Satellite System ◽  
Triple Frequency ◽  
Point Positioning

Compared with the traditional ionospheric-free linear combination precise point positioning (PPP) model, the un-differenced and uncombined (UDUC) PPP model using original observations can keep all the information of the observations and be easily extended to any number of frequencies. However, the current studies about the multi-frequency UDUC-PPP ambiguity resolution (AR) were mainly based on the triple-frequency BeiDou navigation satellite system (BDS) observations or simulated data. Limited by many factors, for example the accuracy of BDS precise orbit and clock products, the advantages of triple-frequency signals to UDUC-PPP AR were not fully exploited. As Galileo constellations have been upgraded by increasing the number of 19 useable satellites, it makes using Galileo satellites to further study the triple-frequency UDUC-PPP ambiguity resolution (AR) possible. In this contribution, we proposed the method of multi-frequency step-by-step ambiguity resolution based on the UDUC-PPP model and gave the reason why the performance of PPP AR can be improved using triple-frequency observations. We used triple-frequency Galileo observations on day of year (DOY) 201, 2018 provided by 166 Multi-GNSS Experiment (MGEX) stations to estimate original uncalibrated phase delays (UPD) on each frequency and to conduct both dual- and triple-frequency UDUC-PPP AR. The performance of UDUC-PPP AR based on post-processing mode was assessed in terms of the time-to-first-fix (TTFF) as well as positioning accuracy with 2-hour observations. It was found that triple-frequency observations were helpful to reduce TTFF and improve the positioning accuracy. The current statistic results showed that triple-frequency PPP-AR reduced the averaged TTFF by 19.6 % and also improved the positioning accuracy by 40.9, 31.2 and 23.6 % in the east, north and up directions respectively, compared with dual-frequency PPP-AR. With an increasing number of Galileo satellites, it is expected that the robustness and accuracy of the triple-frequency UCUD-PPP AR can be improved further.

Improvement of Multi-GNSS Precise Point Positioning Performances with Real Meteorological Data

2018 ◽  
Vol 71 (6) ◽  
pp. 1363-1380 ◽  
Author(s):  
Ke Su ◽  
Shuanggen Jin
Keyword(s):  
Global Navigation Satellite System ◽  
Precise Point Positioning ◽  
Meteorological Data ◽  
Satellite System ◽  
Navigation Satellite ◽  
Positioning Accuracy ◽  
Global Pressure ◽  
Global Navigation ◽  
Point Positioning ◽  
Global Navigation Satellite

Tropospheric delay is one of the main error sources in Global Navigation Satellite System (GNSS) Precise Point Positioning (PPP). Zenith Hydrostatic Delay (ZHD) accounts for 90% of the total delay. This research focuses on the improvements of ZHD from tropospheric models and real meteorological data on the PPP solution. Multi-GNSS PPP experiments are conducted using the datasets collected at Multi-GNSS Experiments (MGEX) network stations. The results show that the positioning accuracy of different GNSS PPP solutions using the meteorological data for ZHD correction can achieve an accuracy level of several millimetres. The average convergence time of a PPP solution for the BeiDou System (BDS), the Global Positioning System (GPS), Global Navigation Satellite System of Russia (GLONASS), BDS+GPS, and BDS+GPS+GLONASS+Galileo are 55·89 min, 25·88 min, 33·30 min, 20·50 min and 15·71 min, respectively. The results also show that atmospheric parameters provided by real meteorological data have little effect on the horizontal components of positioning compared to the meteorological model, while in the vertical component, the positioning accuracy is improved by 90·6%, 33·0%, 22·2% and 19·8% compared with the standard atmospheric model, University of New Brunswick (UNB3m) model, Global Pressure and Temperature (GPT) model, and Global Pressure and Temperature-2 (GPT2) model and the convergence times are decreased 51·2%, 32·8%, 32·5%, and 32·3%, respectively.

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