DAY BY DAY BEHAVIOR OF GNNS POSITIONING ERRORS AND TEC FLUCTUATIONS ASSOCIATED AURORAL DISTURBANCES OVER MARCH 2015

We analyzed the occurrence of TEC fluctuations and an impact of auroral disturbances on the Precise Point Positioning (PPP) errors in European sector using GPS measurements of EPN network. Index AE was used as indicator of auroral activity. The fluctuation activity was evaluated by indexes ROT and ROTI. The positioning errors were determined using the GIPSY-OASIS software (http://apps.gdgps.net). The Precise Point Positioning is the processing strategy of the single receiver for GNSS observations that enables the efficient computation of the high-quality coordinates. For quiet conditions the algorithm provided for TRO1 stations daily average PPP errors less than 4-5 sm. The analysis indicated regular increasing positioning errors around MLT (22 UT) during March 2015. While raising the auroral activity it was observed increasing TEC fluctuation as well as positioning errors. In the report we discus also behavior PPP errors during super storm 17 March 2015. During storm at TRO1 the PPP errors reached more than 20 m. The increasing errors were observed on latitudes low than 52-54°N.

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

GPS Solutions ◽

10.1007/s10291-021-01106-1 ◽

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.

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Precise Point Positioning Using Dual-Frequency GNSS Observations on Smartphone

Sensors ◽

10.3390/s19092189 ◽

2019 ◽

Vol 19 (9) ◽

pp. 2189 ◽

Cited By ~ 27

Author(s):

Qiong Wu ◽

Mengfei Sun ◽

Changjie Zhou ◽

Peng Zhang

Keyword(s):

Precise Point Positioning ◽

Frequency Mode ◽

Single Frequency ◽

Dual Frequency ◽

Static Mode ◽

Position Errors ◽

Point Positioning ◽

Similar Accuracy ◽

Positioning Algorithm ◽

Gnss Observations

The update of the Android system and the emergence of the dual-frequency GNSS chips enable smartphones to acquire dual-frequency GNSS observations. In this paper, the GPS L1/L5 and Galileo E1/E5a dual-frequency PPP (precise point positioning) algorithm based on RTKLIB and GAMP was applied to analyze the positioning performance of the Xiaomi Mi 8 dual-frequency smartphone in static and kinematic modes. The results showed that in the static mode, the RMS position errors of the dual-frequency smartphone PPP solutions in the E, N, and U directions were 21.8 cm, 4.1 cm, and 11.0 cm, respectively, after convergence to 1 m within 102 min. The PPP of dual-frequency smartphone showed similar accuracy with geodetic receiver in single-frequency mode, while geodetic receiver in dual-frequency mode has higher accuracy. In the kinematic mode, the positioning track of the smartphone dual-frequency data had severe fluctuations, the positioning tracks derived from the smartphone and the geodetic receiver showed approximately difference of 3–5 m.

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Performance Analysis of GPS/BDS Precise Point Positioning

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.713-715.1123 ◽

2015 ◽

Vol 713-715 ◽

pp. 1123-1126

Author(s):

Xiao Yu Li ◽

Jun Wang ◽

Ya Tao Liu

Keyword(s):

Precise Point Positioning ◽

Satellite Orbit ◽

Gps Measurements ◽

Differential Code Bias ◽

Phase Offset ◽

Antenna Phase ◽

Offset Correction ◽

Code Bias ◽

Point Positioning ◽

Processing Steps

Precise Point Positioning (PPP) with GPS measurements has achieved a level of success. In order to benefit from the multiple available constellations, research has been undertaken to combineGPS and BDS measurements in PPP processing.Mathematical models of GPS/BDS combined precise point positioning are introduced in this paper. GPS/BDS combined PPP models are developed based on the GPS-only PPP. The data pre-processing steps include applying satellite orbit and clock corrections, satellite antenna phase offset correction, receiver antenna phase offset correction, differential code bias corrections, troposphere delay corrections and the the Ionosphere-free observation combination is used. The results show that the positioning precision and convergence speed of GPS/BDS combined PPP are improved compared with GPS-only PPP.

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Single-Frequency Precise Point Positioning Using Multi-Constellation GNSS: GPS, GLONASS, Galileo and BeiDou

GEOMATICA ◽

10.5623/cig2016-203 ◽

2016 ◽

Vol 70 (2) ◽

pp. 113-122 ◽

Cited By ~ 1

Author(s):

Mahmoud Abd Rabbou ◽

Ahmed El-Rabbany

Keyword(s):

Urban Areas ◽

Precise Point Positioning ◽

Cost Effective ◽

Convergence Time ◽

Single Frequency ◽

Dual Frequency ◽

Positioning Accuracy ◽

Point Positioning ◽

Beidou Satellites ◽

Gnss Observations

Single-frequency precise point positioning (PPP) presents a cost-effective positioning technique for a large number of users. However, it possesses low positioning accuracy and convergence time compared with the dual-frequency PPP. Single-frequency PPP commonly employs GPS satellite systems that suffer from poor satellite geometry, especially in dense urban areas. We develop a new single-frequency PPP model that combines the observations of current GNSS constellations, including GPS, GLONASS, Galileo and Beidou. The MGEX IGS final precise products are utilized to account for the orbital and clock errors, while the IGS final global ionospheric maps (GIM) model is used to correct for the ionospheric delay. The GNSS inter-system biases are treated as additional unknowns in the estimation process. The con tri bution of the additional GNSS observations to single-frequency PPP is assessed through solution comparison with its traditional GPS-only counterpart. Various GNSS combinations are considered in the assessment, including GPS/GLONASS, GPS/Galileo, GPS/BeiDou and all-constellation GNSS. It is shown that the additional GNSS observations enhance the PPP solution accuracy and convergence time in comparison with the tra di tional GPS-only solution. Except for stations with a sufficient number of tracked BeiDou satellites, both Galileo and BeiDou have marginal effects on the positioning accuracy due to their limited number of satel lites. However, for stations with a sufficient number of visible BeiDou satellites, an average of 40% PPP accuracy improvement is obtained. The major contribution to the PPP accuracy enhancement is obtained from GLONASS satellite observations.

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Real-time Precise Point Positioning with a Xiaomi MI 8 Android Smartphone

Sensors ◽

10.3390/s19122835 ◽

2019 ◽

Vol 19 (12) ◽

pp. 2835 ◽

Cited By ~ 18

Author(s):

Bo Chen ◽

Chengfa Gao ◽

Yongsheng Liu ◽

Puyu Sun

Keyword(s):

Real Time ◽

Mobile Phones ◽

Precise Point Positioning ◽

Satellite System ◽

Dual Frequency ◽

Gnss Positioning ◽

Positioning Errors ◽

Positioning Method ◽

Point Positioning ◽

Time Required

The Global Navigation Satellite System (GNSS) positioning technology using smartphones can be applied to many aspects of mass life, and the world’s first dual-frequency GNSS smartphone Xiaomi MI 8 represents a new trend in the development of GNSS positioning technology with mobile phones. The main purpose of this work is to explore the best real-time positioning performance that can be achieved on a smartphone without reference stations. By analyzing the GNSS raw measurements, it is found that all the three mobile phones tested have the phenomenon that the differences between pseudorange observations and carrier phase observations are not fixed, thus a PPP (precise point positioning) method is modified accordingly. Using a Xiaomi MI 8 smartphone, the modified real-time PPP positioning strategy which estimates two clock biases of smartphone was applied. The results show that using multi-GNSS systems data can effectively improve positioning performance; the average horizontal and vertical RMS positioning error are 0.81 and 1.65 m respectively (using GPS, BDS, and Galileo data); and the time required for each time period positioning errors in N and E directions to be under 1 m is less than 30s.

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Weighting of Multi-GNSS Observations in Real-Time Precise Point Positioning

Remote Sensing ◽

10.3390/rs10010084 ◽

2018 ◽

Vol 10 (2) ◽

pp. 84 ◽

Cited By ~ 28

Author(s):

Kamil Kazmierski ◽

Tomasz Hadas ◽

Krzysztof Sośnica

Keyword(s):

Real Time ◽

Precise Point Positioning ◽

Point Positioning ◽

Gnss Observations

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

Sensors ◽

10.3390/s20226447 ◽

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.

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