scholarly journals Exploring Signals on L5/E5a/B2a for Dual-Frequency GNSS Precise Point Positioning

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 2046
Author(s):  
Nacer Naciri ◽  
André Hauschild ◽  
Sunil Bisnath
Keyword(s):  
Real Time ◽  
Precise Point Positioning ◽  
Positive Impact ◽  
Rapid Evolution ◽  
Global Navigation Satellite Systems ◽  
Satellite Orbits ◽  
Dual Frequency ◽  
Point Positioning ◽  
Block Iif ◽  
Gps Block Iif

Due to its nature, Precise Point Positioning (PPP) depends on the GNSS measurements and quality of satellite correction products used to relatively quickly provide precise and accurate positions. With the rapid evolution of Global Navigation Satellite Systems (GNSSs), new frequencies and signals are being broadcast, which have a positive impact on PPP performance. This paper presents, for the first time, a comprehensive analysis of PPP performance from these new GPS, Galileo and BeiDou-2/3 signals, which are not yet commonly used for PPP, with correct mitigation of errors such as the estimation of GPS Block-IIF L5 variations. Satellite orbits and clocks, as well as GPS Block-IIF L5 corrections, are estimated in real-time using DLR’s RETICLE engine, while the user processing is performed with York University’s PPP engine. First, as a reference, PPP performance is assessed on widely used signals: GPS L1/L2, Galileo E1/E5a, and BeiDou-2/3 B1-2/B3. Horizontal and vertical rms of 2.3 and 2.6 cm, respectively, are achieved in static processing and 5.4 and 7.5 cm in kinematic processing after 1 h of processing using real-time satellite correction products. The compatibility of BeiDou-2 and BeiDou-3 on the shared B1-2/B3 frequencies is analyzed and discrepancies in the receiver clock are found. Next, since all three constellations share two common frequencies, the paper focuses on analyzing PPP performance of GPS, Galileo and BeiDou-3 on [L1, E1, B1] at 1575.42 MHz and [L5, E5a, B2a] at 1176.45 MHz. Horizontal and vertical rms of 6.9 and 7.1 cm are achieved in kinematic processing. The effect of the known GPS Block-IIF L5 biases is studied as well, as it is shown to affect the receiver position and clock, as well as the ionospheric estimates and ambiguities. Average improvements of 15% and 20% in the horizontal and vertical rms, respectively, are observed when these biases are mitigated.

scholarly journals Precise Point Positioning Using the Regional BeiDou Navigation Satellite Constellation

2014 ◽  
Vol 67 (3) ◽  
pp. 523-537 ◽  
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.

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

Sensors ◽  
2019 ◽  
Vol 19 (12) ◽  
pp. 2835 ◽  
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.

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

2016 ◽  
Vol 10 (4) ◽  
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.

scholarly journals Changes in the GNSS precise point positioning accuracy during a strong geomagnetic storm

2020 ◽  
Vol 196 ◽  
pp. 01001
Author(s):  
Anna Yasyukevich ◽  
Semen Syrovatskii ◽  
Yury Yasyukevich
Keyword(s):  
Geomagnetic Storm ◽  
Precise Point Positioning ◽  
Global Navigation Satellite Systems ◽  
Maximum Effect ◽  
Electron Content ◽  
Dual Frequency ◽  
Period Range ◽  
Positioning Accuracy ◽  
Total Electron ◽  
Point Positioning

Based on the data from dual-frequency receivers of global navigation satellite systems (GNSS), we analyze the changes in GNSS positioning accuracy during the August 25-26, 2018 strong geomagnetic storm on a global scale. The storm is one of the strongest geomagnetic events of the solar cycle 24. To analyze the positioning quality, we calculated coordinates using the precise point positioning (PPP) method in the kinematic mode. We recorder a significant degradation in the PPP positioning accuracy during the main phase of the storm. The maximum effect is observed in the middle and high latitudes of the US-Atlantic longitude sector. The average PPP error during the storm is shown to exceed ~0.5 m, that is up to 5 times higher than the values typical on quiet days. Areas with increased PPP errors is revealed to correspond to the regions with significant increase in the intensity of total electron content variations of 10–20 min period range. This increase is presumably due to the auroral oval expansion toward middle latitudes.

scholarly journals A Smart Realtime Service to Broadcast the Precise Orbits of GPS Satellite and Its Performance on Precise Point Positioning

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3276
Author(s):  
Dehai Li ◽  
Wei Yan ◽  
Jinzhong Mi ◽  
Yamin Dang ◽  
Yunbin Yuan ◽  
...  
Keyword(s):  
Real Time ◽  
Data Stream ◽  
Precise Point Positioning ◽  
Rapid Development ◽  
Relative Distance ◽  
Satellite Orbits ◽  
Gps Navigation ◽  
Point Positioning ◽  
The Difference ◽  
First Time

At present, Global Position System (GPS) navigation ephemeris mainly broadcasts satellite orbits with meter-level precision for standard point positioning and precise relative positioning. With the rapid development of real-time precise point positioning (PPP), the receiver or smartphone has begun to demand more and more convenient, continuous, and reliable access to real-time services of precise orbits. Therefore, this study proposes a solution of utilizing the 18-parameter ephemeris to directly broadcast ultra-rapid precise predicted orbits with centimeter-level precision for real-time PPP. For the first time in GPS, the difference in the PPP results between the precise orbits and the calculated orbits broadcasted from the generated ephemeris parameters is supplied as follows: (1) During the validity period of 2 h, root mean square (RMS) of the relative distance offsets between the results of PPP with the precise orbits and the results of PPP the 18-parameter ephemeris is only 0.0098 m. (2) Within 15 min after the validity period of 2 h, RMS of the relative distance offsets between the results of PPP with the precise orbits and the results of PPP with the predicted orbits by 18-parameter ephemeris is only 0.0057 m. Consequently, the 18-parameter ephemeris is feasible and advisable to broadcast precise predicted orbits for real-time PPP applications. Compared with the classic precise orbits broadcast mode with the orbit corrections defined by the radio technical commission for maritime services standards 10403.2 (RTCM), the mode of broadcasting the precise orbits with the 18-parameter ephemeris achieved the following improvements in convenience, continuity, and reliability: (1) The calculation of satellite position is the same as that of the navigation ephemeris excluding the additional correction operations required to the RTCM; (2) the amount of broadcast parameters was reduced by 20 times; (3) the length of the validity period was expanded 120 times, where the longer valid period helped to overcome the orbit corrections loss caused by RTCM stream failures; and (4) within 15 min after the validity period, the predicted orbits with an accuracy of 2 cm could still be provided by the 18-parameter ephemeris, which can ensure the real-time services of precise orbits in the case of a 15 min communication interruption of the RTCM orbit correction data stream.

scholarly journals Ocean Real-Time Precise Point Positioning with the BeiDou Short-Message Service

2020 ◽  
Vol 12 (24) ◽  
pp. 4167
Author(s):  
Kaifei He ◽  
Duojie Weng ◽  
Shengyue Ji ◽  
Zhenjie Wang ◽  
Wu Chen ◽  
...  
Keyword(s):  
Real Time ◽  
Data Transmission ◽  
Short Message Service ◽  
Precise Point Positioning ◽  
Maximum Size ◽  
Global Navigation Satellite Systems ◽  
Short Message ◽  
Time Service ◽  
Message Service ◽  
Point Positioning

Real-time precise point positioning (RTPPP) is a popular positioning method that uses a real-time service (RTS) product to mitigate various Global Navigation Satellite Systems (GNSS) errors. However, communication links are not available in the ocean. The use of a communication satellite for data transmission is so expensive that normal users could not afford it. The BeiDou short-message service provides an efficient option for data transmission at sea, with an annual fee of approximately 160 USD. To perform RTPPP using BeiDou short messages, the following two challenges should be appropriately addressed: the maximum size of each BeiDou message is 78 bytes, and the communication frequency is limited to once a minute. We simplify the content of RTS data to minimize the required bandwidth. Moreover, the orbit and clock corrections are predicted based on minute-interval RTS orbital and clock corrections. An experiment was conducted to test the performance of the proposed method. The numerical results show that the three-dimensional positioning precision can reach approximately 0.4 m with combined GPS + GLONASS and approximately 0.2 m with combined GPS + GLONASS + Galileo + BeiDou.

Determining the Coordinates of Control Points in Hydrographic Surveying by the Precise Point Positioning Method

2017 ◽  
Vol 70 (6) ◽  
pp. 1241-1252
Author(s):  
Burak Akpınar ◽  
Nedim Onur Aykut
Keyword(s):  
Precise Point Positioning ◽  
Global Navigation Satellite Systems ◽  
Reference Station ◽  
Control Points ◽  
Dual Frequency ◽  
Satellite Systems ◽  
Positioning Method ◽  
Test Points ◽  
Point Positioning ◽  
Hydrographic Surveying

After Global Navigation Satellite Systems (GNSS) were first used in the field of hydrography in 1980, developments in hydrographic surveying accelerated. Survey precision in hydrography has been improved for both horizontal and vertical positioning and seafloor acoustic measurement by means of these new developments. Differential Global Positioning System (DGPS), Real Time Kinematic (RTK) and Network RTK (NRTK) techniques are the satellite-based positioning techniques that are commonly used in shallow water surveys and shoreline measurements. In line with these developments, the newer Precise Point Positioning (PPP) has been introduced. Combining precise satellite positions and clocks with dual-frequency GNSS data, PPP can provide position solutions from the centimetre to decimetre level. In this study, the coordinates of control points were determined by using the Post-Process PPP (PP-PPP) technique. Seven test points, which are the points of the Continuously Operating Reference Station - Turkey (CORS-TR) network, are selected near the shorelines within Turkey. The 24-hour data was split from one to six hours by one hour periods. Automatic Point Positioning Service (APPS) was selected to process the data. The poisoning error of the test points were given and compared with International Hydrographic Organization (IHO) S44 hydrographic survey standards.

scholarly journals Precise Point Positioning Using Triple GNSS Constellations in Various Modes

2021 ◽  
Author(s):  
Akram Afifi ◽  
Ahmed El-Rabbany
Keyword(s):  
Linear Combination ◽  
Real Time ◽  
Precise Point Positioning ◽  
Satellite Orbit ◽  
Convergence Time ◽  
Dual Frequency ◽  
Post Processing ◽  
Time Service ◽  
Reference Satellite ◽  
Point Positioning

This paper introduces a new dual-frequency precise point positioning (PPP) model, which combines the observations from three different global navigation satellite system (GNSS) constellations, namely GPS, Galileo, and BeiDou. Combining measurements from different GNSS systems introduces additional biases, including inter-system bias and hardware delays, which require rigorous modelling. Our model is based on the un-differenced and between-satellite single-difference (BSSD) linear combinations. BSSD linear combination cancels out some receiver-related biases, including receiver clock error and non-zero initial phase bias of the receiver oscillator. Forming the BSSD linear combination requires a reference satellite, which can be selected from any of the GPS, Galileo, and BeiDou systems. In this paper three BSSD scenarios are tested; each considers a reference satellite from a different GNSS constellation. Natural Resources Canada’s GPSPace PPP software is modified to enable a combined GPS, Galileo, and BeiDou PPP solution and to handle the newly introduced biases. A total of four data sets collected at four different IGS stations are processed to verify the developed PPP model. Precise satellite orbit and clock products from the International GNSS Service Multi-GNSS Experiment (IGS-MGEX) network are used to correct the GPS, Galileo, and BeiDou measurements in the post-processing PPP mode. A real-time PPP solution is also obtained, which is referred to as RT-PPP in the sequel, through the use of the IGS real-time service (RTS) for satellite orbit and clock corrections. However, only GPS and Galileo observations are used for the RT-PPP solution, as the RTS-IGS satellite products are not presently available for BeiDou system. All post-processed and real-time PPP solutions are compared with the traditional un-differenced GPS-only counterparts. It is shown that combining the GPS, Galileo, and BeiDou observations in the post-processing mode improves the PPP convergence time by 25% compared with the GPS-only counterpart, regardless of the linear combination used. The use of BSSD linear combination improves the precision of the estimated positioning parameters by about 25% in comparison with the GPS-only PPP solution. Additionally, the solution convergence time is reduced to 10 minutes for the BSSD model, which represents about 50% reduction, in comparison with the GPS-only PPP solution. The GNSS RT-PPP solution, on the other hand, shows a similar convergence time and precision to the GPS-only counterpart.

An investigation into the performance of real-time GPS+GLONASS Precise Point Positioning (PPP) in New Zealand

2017 ◽  
Vol 11 (3) ◽  
Author(s):  
Ken Harima ◽  
Suelynn Choy ◽  
Chris Rizos ◽  
Satoshi Kogure
Keyword(s):  
New Zealand ◽  
Real Time ◽  
Precise Point Positioning ◽  
Vertical Component ◽  
Satellite Orbit ◽  
Satellite System ◽  
Global Navigation Satellite Systems ◽  
The Real ◽  
Satellite Systems ◽  
Point Positioning

AbstractThis paper presents an investigation into the performance of real-time Global Navigation Satellite Systems (GNSS) Precise Point Positioning (PPP) in New Zealand. The motivation of the research is to evaluate the feasibility of using PPP technique and a satellite based augmentation system such as the Japanese Quasi-Zenith Satellite System (QZSS) to deliver a real-time precise positioning solution in support of a nation-wide high accuracy GNSS positioning coverage in New Zealand. Two IGS real-time correction streams are evaluated alongside with the PPP correction messages transmitted by the QZSS satellite known as MDC1. MDC1 corrections stream is generated by Japan Aerospace Exploration Agency (JAXA) using the Multi-GNSS Advanced Demonstration tool for Orbit and Clock Analysis (MADOCA) software and are currently transmitted in test mode by the QZSS satellite. The IGS real-time streams are the CLK9B real-time corrections stream generated by the French Centre National D’études Spatiales (CNES) using the PPP-Wizard software, and the CLK81 real-time corrections stream produced by GMV using their MagicGNSS software. GNSS data is collected from six New Zealand CORS stations operated by Land Information New Zealand (LINZ) over a one-week period in 2015. GPS and GLONASS measurements are processed in a real-time PPP mode using the satellite orbit and clock corrections from the real-time streams. The results show that positioning accuracies of 6 cm in horizontal component and 15 cm in vertical component can be achieved in real-time PPP. The real-time GPS+GLONASS PPP solution required 30 minutes to converge to within 10 cm horizontal positioning accuracy.

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