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

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.

Download Full-text

GLONASS Aided GPS Ambiguity Fixed Precise Point Positioning

Journal of Navigation ◽

10.1017/s0373463313000052 ◽

2013 ◽

Vol 66 (3) ◽

pp. 399-416 ◽

Cited By ~ 20

Author(s):

Altti Jokinen ◽

Shaojun Feng ◽

Wolfgang Schuster ◽

Washington Ochieng ◽

Chris Hide ◽

...

Keyword(s):

Ambiguity Resolution ◽

Precise Point Positioning ◽

Satellite System ◽

Integer Ambiguity ◽

Convergence Time ◽

Reference Network ◽

Positioning Errors ◽

Point Positioning ◽

Time Required ◽

Global Navigation Satellite

The Precise Point Positioning (PPP) concept enables centimetre-level positioning accuracy by employing one Global Navigation Satellite System (GNSS) receiver. The main advantage of PPP over conventional Real Time Kinematic (cRTK) methods is that a local reference network infrastructure is not required. Only a global reference network with approximately 50 stations is needed because reference GNSS data is required for generating precise error correction products for PPP. However, the current implementation of PPP is not suitable for some applications due to the long time period (i.e. convergence time of up to 60 minutes) required to obtain an accurate position solution. This paper presents a new method to reduce the time required for initial integer ambiguity resolution and to improve position accuracy. It is based on combining GPS and GLONASS measurements to calculate the float ambiguity positioning solution initially, followed by the resolution of GPS integer ambiguities.The results show that using the GPS/GLONASS float solution can, on average, reduce the time to initial GPS ambiguity resolution by approximately 5% compared to using the GPS float solution alone. In addition, average vertical and horizontal positioning errors at the initial ambiguity resolution epoch can be reduced by approximately 17% and 4%, respectively.

Download Full-text

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.

Download Full-text

Precise Point Positioning Using the Regional BeiDou Navigation Satellite Constellation

Journal of Navigation ◽

10.1017/s0373463313000842 ◽

2014 ◽

Vol 67 (3) ◽

pp. 523-537 ◽

Cited By ~ 7

Author(s):

Aigong Xu ◽

Zongqiu Xu ◽

Xinchao Xu ◽

Huizhong Zhu ◽

Xin Sui ◽

...

Keyword(s):

Real Time ◽

Precise Point Positioning ◽

Satellite System ◽

Convergence Time ◽

Asia Pacific ◽

Satellite Orbits ◽

Navigation Satellite ◽

Asia Pacific Region ◽

Point Positioning

On 27 December 2012 it was announced officially that the Chinese Navigation Satellite System BeiDou (BDS) was able to provide operational services over the Asia-Pacific region. The quality of BDS observations was confirmed as comparable with those of GPS, and relative positioning in static and kinematic modes were also demonstrated to be very promising. As Precise Point Positioning (PPP) technology is widely recognized as a method of precise positioning service, especially in real-time, in this contribution we concentrate on the PPP performance using BDS data only. BDS PPP in static, kinematic and simulated real-time kinematic mode is carried out for a regional network with six stations equipped with GPS- and BDS-capable receivers, using precise satellite orbits and clocks estimated from a global BDS tracking network. To validate the derived positions and trajectories, they are compared to the daily PPP solution using GPS data. The assessment confirms that the performance of BDS PPP is very comparable with GPS in terms of both convergence time and accuracy.

Download Full-text

Real-Time Precise Point Positioning Using Orbit and Clock Corrections as Quasi-Observations for Improved Detection of Faults

Journal of Navigation ◽

10.1017/s0373463317001023 ◽

2018 ◽

Vol 71 (4) ◽

pp. 769-787 ◽

Cited By ~ 7

Author(s):

Ahmed El-Mowafy

Keyword(s):

Real Time ◽

Precise Point Positioning ◽

Exclusion Process ◽

Satellite Orbit ◽

Satellite System ◽

Navigation Satellite ◽

System Service ◽

Point Positioning ◽

Predicted Values ◽

Global Navigation Satellite

Real-time Precise Point Positioning (PPP) relies on the use of accurate satellite orbit and clock corrections. If these corrections contain large errors or faults, either from the system or by meaconing, they will adversely affect positioning. Therefore, such faults have to be detected and excluded. In traditional PPP, measurements that have faulty corrections are typically excluded as they are merged together. In this contribution, a new PPP model that encompasses the orbit and clock corrections as quasi-observations is presented such that they undergo the fault detection and exclusion process separate from the observations. This enables the use of measurements that have faulty corrections along with predicted values of these corrections in place of the excluded ones. Moreover, the proposed approach allows for inclusion of the complete stochastic information of the corrections. To facilitate modelling of the orbit and clock corrections as quasi-observations, International Global Navigation Satellite System Service (IGS) real-time corrections were characterised over a six-month period. The proposed method is validated and its benefits are demonstrated at two sites using three days of data.

Download Full-text

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

Remote Sensing ◽

10.3390/rs11030311 ◽

2019 ◽

Vol 11 (3) ◽

pp. 311 ◽

Cited By ~ 3

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.

Download Full-text

Research on Real-Time Precise Point Positioning Method Based on Short Message Communication

10.1007/978-981-16-3138-2_51 ◽

2021 ◽

pp. 547-559

Author(s):

Runxi Yang ◽

Liang Li ◽

Fuxin Yang ◽

Jie Zhang ◽

Lin Zhao

Keyword(s):

Real Time ◽

Precise Point Positioning ◽

Short Message ◽

Message Communication ◽

Positioning Method ◽

Point Positioning

Download Full-text

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.

Download Full-text

Precise Point Positioning Model Using Triple GNSS Constellations: GPS, Galileo and BeiDou

Journal of Applied Geodesy ◽

10.1515/jag-2016-0010 ◽

2016 ◽

Vol 10 (4) ◽

Cited By ~ 1

Author(s):

Akram Afifi ◽

Ahmed El-Rabbany

Keyword(s):

Real Time ◽

Urban Areas ◽

Precise Point Positioning ◽

Convergence Time ◽

Dual Frequency ◽

Post Processing ◽

International Gnss Service ◽

Time Service ◽

System Bias ◽

Point Positioning

AbstractThis paper introduces a comparison between dual-frequency precise point positioning (PPP) post-processing model, which combines the observations of three different GNSS constellations, namely GPS, Galileo, and BeiDou and real-time PPP model. A drawback of a single GNSS system such as GPS, however, is the availability of sufficient number of visible satellites in urban areas. Combining GNSS observations offers more visible satellites to users, which in turn is expected to enhance the satellite geometry and the overall positioning solution. However, combining several GNSS observables introduces additional biases, which require rigorous modelling, including the GNSS time offsets and hardware delays. In this paper, a GNSS post-processing PPPP model is developed using ionosphere-free linear combination. The additional biases of the GPS, Galileo, and BeiDou combination are accounted for through the introduction of a new unknown parameter, which is identified as the inter-system bias, in the PPP mathematical model. Natural Resources Canada’s GPSPace PPP software is modified to enable a combined GPS / Galileo / BeiDou PPP solution and to handle the newly inter-system bias. A total of four data sets at four IGS stations are processed to verify the developed PPP model. Precise satellite orbit and clock products from the IGS-MGEX network are used to correct of the GPS, Galileo and BeiDou measurements. For the real-time PPP model the corrections of the satellites orbit and clock are obtained through the international GNSS service (IGS) real-time service (RTS). GPS and Galileo Observations are used for the GNSS RTS-IGS PPP model as the RTS-IGS satellite products are not available for BeiDou satellites. This paper provides the GNSS RTS-IGS PPP model using different satellite clock corrections namely: IGS01, IGC01, IGS01, and IGS03. All PPP models results of convergence time and positioning precision are compared to the traditional GPS-only PPP model. It is shown that combining GPS, Galileo, and BeiDou observations in a PPP model reduces the convergence time by 25 % compared with the GPS-only PPP model.

Download Full-text

PENGGUNAAN KINEMATIK GNSS PRECISE POINT POSITIONING (PPP) PADA SURVEI GAYABERAT AIRBORNE SULAWESI

GEOMATIKA ◽

10.24895/jig.2016.22-2.638 ◽

2016 ◽

Vol 22 (2) ◽

pp. 82

Author(s):

Prayudha Hartanto

Keyword(s):

Precise Point Positioning ◽

Base Station ◽

Gravity Survey ◽

Airborne Gravity ◽

Dual Frequency ◽

Differential Gps ◽

Airborne Gravity Survey ◽

Positioning Method ◽

Rms Error ◽

Point Positioning

ABSTRAKMetode Precise Point Positioning (PPP) adalah metode penentuan posisi teliti yang hanya menggunakan sebuah receiver GNSS dual frekuensi. Metode ini dapat digunakan untuk menentukan posisi teliti objek-objek yang diam (static) maupun bergerak (kinematic). Pada penelitian ini, akan dipaparkan mengenai penggunaan kinematik PPP dalam penentuan posisi pesawat terbang pada survei gayaberat airborne di Sulawesi tahun 2008. Data yang digunakan adalah jalur terbang pesawat pada day of year (DOY) 291 dan 274. Perangkat lunak yang digunakan adalah Waypoint® Grafnav. Hasil pengolahan menggunakan metode PPP tersebut kemudian dibandingkan dengan hasil pengolahan data Diferensial GPS (DGPS) dengan 1 titik ikat untuk DOY 291 dan 2 titik ikat untuk DOY 274. Hasil perbandingan pada DOY 291 menunjukkan nilai RMS untuk arah timur, utara dan tinggi masing-masing sebesar 0,024 m; 0,020 m dan 0,039 m. Pada DOY 274, RMS yang diperoleh adalah 0,032 m; 0,011 m dan 0,058 m masing-masing untuk arah timur, utara dan tinggi. Hasil-hasil tersebut mengindikasikan bahwa metode PPP dapat digunakan untuk menentukan posisi pesawat terbang dengan fraksi ketelitian sentimeter. Tingkat ketelitian posisi ini sudah memenuhi syarat untuk digunakan pada survei gayaberat airborne.Kata kunci: GNSS, kinematik PPP, gayaberat airborne, DGPS ABSTRACTThe Precise Point Positioning (PPP) is a positioning method which only use a dual frequency GNSS receiver. This method can be used to determine the precise position of either static (static) or moving objects (kinematic). In this paper, we will discuss the application of kinematic PPP for the 2008 Sulawesi airborne gravity survey. By using a commercial GNSS processing software called Waypoint® Grafnav, we determine the PPP solutions for the aircraft trajectory of the day of year (DOY) 291 and 274. Each solution then be compared to the Differential GPS (DGPS) results, which use one base station for DOY 291 and two reference stations for DOY 274. The PPP solution of DOY 291 gives RMS error of 0.024 m eastward, 0.020 m northward, and 0.039 m upward. Moreover, the comparison of DOY 274 gives RMS error of 0.032 m eastward, 0.011 m northward, and 0.058 m upward. These centimeter level RMS errors show that PPP is a compatible positioning method for airborne gravity survey.Keywords: GNSS, kinematic PPP, airborne gravity, DGPS

Download Full-text

Analysis on the Potential Performance of GPS and Galileo Precise Point Positioning using Simulated Real-Time Products

Journal of Navigation ◽

10.1017/s0373463318000577 ◽

2018 ◽

Vol 72 (1) ◽

pp. 19-33 ◽

Cited By ~ 4

Author(s):

Francesco Basile ◽

Terry Moore ◽

Chris Hill

Keyword(s):

Real Time ◽

Precise Point Positioning ◽

Satellite System ◽

Convergence Time ◽

Alternative Methods ◽

International Gnss Service ◽

Binary Offset Carrier ◽

Time Service ◽

Point Positioning ◽

The Impact

With the evolving Global Navigation Satellite System (GNSS) landscape, the International GNSS Service (IGS) has started the Multi-GNSS Experiment (MGEX) to produce precise products for new generation systems. Various analysis centres are working on the estimation of precise orbits, clocks and bias for Galileo, Beidou and Quasi-Zenith Satellite System (QZSS) satellites. However, at the moment these products can only be used for post-processing applications. Indeed, the IGS Real-Time service only broadcasts Global Positioning System (GPS) and Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS) corrections. In this research, a simulator of multi-GNSS observations and real-time precise products has been developed to analyse the performance of GPS-only, Galileo-only and GPS plus Galileo Precise Point Positioning (PPP). The error models in the simulated orbits and clocks were based on the difference between the GPS Real-Time and the Final products. Multiple scenarios were analysed, considering different signals combined in the Ionosphere Free linear combination. Results in a simulated open area environment show better performance of the Galileo-only case over the GPS-only case. Indeed, up 33% and 29% of improvement, respectively, in the accuracy level and convergence time can be observed when using the full Galileo constellation compared to GPS. The dual constellation case provides good improvements, in particular in the convergence time (47% faster than GPS). This paper will also consider the impact of different linear combinations of the Galileo signals, and the potential of the E5 Alternative Binary Offset Carrier (AltBOC) signal. Even though it is significantly more precise than E5a, the PPP performance obtained with the Galileo E1-E5a combination is either better or similar to the one with Galileo E1-E5. The reason for this inconsistency was found in the use of the ionosphere free combination with E1. Finally, alternative methods of ionosphere error mitigation are considered in order to ensure the best possible positioning performance from the Galileo E5 signal in multi-frequency PPP.

Download Full-text