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KinematiC PPP using mixed GPS/GLONASS single-frequency observations

Hamed Mostafa, Abdallah Ashraf, Farah Ashraf

Artificial Satellites : Journal of Planetary Geodesy

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2019

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Vol. 54, No. 3

97--112

EN

Nowadays, Precise Point Positioning (PPP) is a very popular technique for Global Navigation Satellite System (GNSS) positioning. The advantage of PPP is its low cost as well as no distance limitation when compared with the differential technique. Singlefrequency receivers have the advantage of cost effectiveness when compared with the expensive dual-frequency receivers, but the ionosphere error makes a difficulty to be completely mitigated. This research aims to assess the effect of using observations from both GPS and GLONASS constellations in comparison with GPS only for kinematic purposes using single-frequency observations. Six days of the year 2018 with single-frequency data for the Ethiopian IGS station named “ADIS” were processed epoch by epoch for 24 hours once with GPS-only observations and another with GPS/GLONASS observations. In addition to “ADIS” station, a kinematic track in the New Aswan City, Aswan, Egypt, has been observed using Leica GS15, geodetic type, dual-frequency, GPS/GLONASS GNSS receiver and singlefrequency data have been processed. Net_Diff software was used for processing all the data. The results have been compared with a reference solution. Adding GLONASS satellites significantly improved the satellite number and Position Dilution Of Precision (PDOP) value and accordingly improved the accuracy of positioning. In the case of “ADIS” data, the 3D Root Mean Square Error (RMSE) ranged between 0.273 and 0.816 m for GPS only and improved to a range from 0.256 to 0.550 m for GPS/GLONASS for the 6 processed days. An average improvement ratio of 24%, 29%, 30%, and 29% in the east, north, height, and 3D position components, respectively, was achieved. For the kinematic trajectory, the 3D position RMSE improved from 0.733 m for GPS only to 0.638 m for GPS/GLONASS. The improvement ratios were 7%, 5%, 28%, and 13% in the east, north, height, and 3D position components, respectively, for the kinematic trajectory data. This opens the way to add observations from the other two constellations (Galileo and BeiDou) for more accuracy in future research.

2

Pozycjonowanie satelitarne techniką PPP RTK

Uznański A.

Zeszyty Naukowo-Techniczne Stowarzyszenia Inżynierów i Techników Komunikacji w Krakowie. Seria: Materiały Konferencyjne

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2018

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Nr 1(115)

105--122

PL

W toku rozwoju pomiarów satelitarnych pojawiła się technika określana mianem Precise Point Positioning RTK (Real Time Kinematic), która umożliwia precyzyjne wyznaczanie pozycji punktów w czasie rzeczywistym jednym odbiornikiem satelitarnym. Pozycjonowanie tą techniką nie wymaga dostępu do strumieni danych z naziemnych sieci referencyjnych, jak np. w Polsce ASG-EUPOS. Jest to atut szczególnie na obszarach bez zasięgu sieci GSM. Idea tych pomiarów mogłaby się wydawać bardzo atrakcyjną dla wykonawców robót geodezyjnych. W pracy przedstawiono podstawy teoretyczne, akcentując wymagania, atuty i mankamenty tej techniki pomiarowej. Analiza techniki PPP RTK wskazuje na umiarkowane możliwości ich ekonomicznie uzasadnionego zastosowania w praktyce, ale technika nieustannie jest rozwijana i w przyszłości może być bardziej konkurencyjna w Polsce.

EN

During the development of satellite measurements, a technique called Precise Point Positioning RTK (Real Time Kinematic) has emerged. It enables us to determine precisely position in real time with a single satellite receiver. Positioning with this technique does not require access to data streams from terrestrial reference networks, such as ASG-EUPOS in Poland. This is an advantage especially in areas with no GSM coverage. The idea of these measurements might seem very attractive for geodetic contractors. The work presents theoretical foundations, emphasizing the requirements, advantages and drawbacks of this measurement technique. The analysis of the PPP RTK technique indicates moderate possibilities of their economically justified application in practice, but the technique is constantly developed and it may be more competitive in Poland in the future.

3

Wpływ precyzyjnych produktów IGS w pozycjonowaniu statku powietrznego w nawigacji lotniczej

Krasuski K.

Pomiary Automatyka Robotyka

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2018

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R. 22, nr 2

61--66

PL

W pracy przedstawiono rezultaty pozycjonowania statku powietrznego Cessna 172 w nawigacji lotniczej z użyciem techniki pomiarowej PPP. Eksperyment badawczy przeprowadzono z użyciem nieróżnicowych obserwacji GPS zarejestrowanych przez odbiornik pokładowy Topcon HiperPro. Pozycja samolotu Cessna 172 została odtworzona w programie gLAB. W artykule opisano pełny algorytm dla techniki pomiarowej PPP oraz przedstawiono konfigurację modułu PPP w programie gLAB. W obliczeniach wykorzystano precyzyjne produkty służby IGS, tzn. dane efemerydalne i zegary satelitów GPS. W obliczeniach uzyskano wartości błędów średnich wyznaczenia pozycji samolotu Cessna 172 na poziomie niższym niż 0,10 m.

EN

In paper, the results of aircraft positioning in air navigation based on Precise Point Positioning method were presented. The research test was realized using undifference GPS observations recorded by Topcon HiperPro onboard receiver. The position of Cessna 172 aircraft was recovery using gLAB software package. In paper, the full algorithm of PPP method was described and configuration of PPP module in gLAB software was presented. The precise products of IGS service, e. g. GPS ephemeris data and satellite clocks were applied in numerical computations in gLAB software. The obtained values of mean errors of position of Cessna 172 aircraft was lower than 0.10 m in computations mode.

4

Kinematic-PPP using single/dual frequency observations from (GPS, GLONASS and GPS/GLONASS) constellations for hydrography

Farah Ashraf

Artificial Satellites : Journal of Planetary Geodesy

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2018

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Vol. 53, No. 1

37--46

EN

Global Positioning System (GPS) technology is ideally suited for inshore and offshore positioning because of its high accuracy and the short observation time required for a position fix. Precise point positioning (PPP) is a technique used for position computation with a high accuracy using a single GNSS receiver. It relies on highly accurate satellite position and clock data that can be acquired from different sources such as the International GNSS Service (IGS). PPP precision varies based on positioning technique (static or kinematic), observations type (single or dual frequency) and the duration of observations among other factors. PPP offers comparable accuracy to differential GPS with safe in cost and time. For many years, PPP users depended on GPS (American system) which considered the solely reliable system. GLONASS’s contribution in PPP techniques was limited due to fail in maintaining full constellation. Yet, GLONASS limited observations could be integrated into GPS-based PPP to improve availability and precision. As GLONASS reached its full constellation early 2013, there is a wide interest in PPP systems based on GLONASS only and independent of GPS. This paper investigates the performance of kinematic PPP solution for the hydrographic applications in the Nile river (Aswan, Egypt) based on GPS, GLONASS and GPS/GLONASS constellations. The study investigates also the effect of using two different observation types; single-frequency and dual frequency observations from the tested constellations.

5

A comparative study of Precise Point Positioning (PPP) accuracy using online services

Malinowski M., Kwiecień J.

Reports on Geodesy and Geoinformatics

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2016

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Vol. 102

15--31

EN

Precise Point Positioning (PPP) is a technique used to determine the position of receiver antenna without communication with the reference station. It may be an alternative solution to differential measurements, where maintaining a connection with a single RTK station or a regional network of reference stations RTN is necessary. This situation is especially common in areas with poorly developed infrastructure of ground stations. A lot of research conducted so far on the use of the PPP technique has been concerned about the development of entire day observation sessions. However, this paper presents the results of a comparative analysis of accuracy of absolute determination of position from observations which last between 1 to 7 hours with the use of four permanent services which execute calculations with PPP technique such as: Automatic Precise Positioning Service (APPS), Canadian Spatial Reference System Precise Point Positioning (CSRS-PPP), GNSS Analysis and Positioning Software (GAPS) and magicPPP - Precise Point Positioning Solution (magicGNSS). On the basis of acquired results of measurements, it can be concluded that at least two-hour long measurements allow acquiring an absolute position with an accuracy of 2-4 cm. An evaluation of the impact on the accuracy of simultaneous positioning of three points test network on the change of the horizontal distance and the relative height difference between measured triangle vertices was also conducted. Distances and relative height differences between points of the triangular test network measured with a laser station Leica TDRA6000 were adopted as references. The analyses of results show that at least two hours long measurement sessions can be used to determine the horizontal distance or the difference in height with an accuracy of 1-2 cm. Rapid products employed in calculations conducted with PPP technique reached the accuracy of determining coordinates on a close level as in elaborations which employ Final products.

6

Impact of ocean tides loading on Precise Point Positioning based on FES2004 model

Kalita J. Z., Rzepecka Z.

Artificial Satellites : Journal of Planetary Geodesy

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2015

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Vol. 50, No. 2

77--89

EN

Precise Point Positioning (PPP) technique as an absolute positioning method requires modeling of effects that influence observations. One of the effects is a displacement of the measurement location due to ocean mass gravitational attraction - ocean tides loading (OTL). The model recommended by the International Earth Rotation and Reference Systems Service (IERS) is FES2004. The paper focuses on impact of applying the particular OTL model on PPP processing. The analysis is based on processing of observations from 24 globally distributed permanent stations and time span of 50 days. The analysis bases on processing intervals from 1 to 24 hours. In addition, the amplitudes of the loads in Poland are evaluated. The OTL model is location dependent, thus the importance of applying this model depends on the location environment. As the PPP is an absolute method, the loads cumulate and transfer nearly directly to the positioning solution. Consequently, for short observation intervals and small loads the application of the model does not play an important role. For the analysed station with high amplitudes of the loads the relative and absolute improvement, of the solution was the highest for height component. By applying the model, the solution improved by 19% or 7.3 mm (as for RMS and 8 hour interval). The distinct improvement for convergence exists for vertical component and threshold below 5 cm. For Poland the vertical component loads were about 5 times smaller and the highest improvement for the analysed station was 3.7% for 4 hour interval and vertical component.

7

Possibilities of detection of seismic displacements in Central Europe by analysis of high-rate GPS

Hefty J., Gerhátová L.

Reports on Geodesy

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2012

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z. 2/93

25--33

EN

The Precise Point Positioning (PPP) analysis technique adapted for monitoring of high - rate coordinate variations from GPS observations is applied for detection of actual displacements related to moderate and light earthquakes. Two approaches are examined: kinematic PPP which is suitable for larger displacements and analysis of residuals from quasi-static PPP which is suitable for detection of min or earthquake related displacements. The potential and limits of the se used methods are documented on M 6.3 L’Aquila earthquake and M 4.3 Tatabanya earthquake. Our experiments proved the ability to measure dynamic seismic-related short-term coordinate variations at sub-centimetre level with PPP using GPS 1 Hz satellites observations.

8

Time transfer realized by PPP technique for TRIMBLE NetRS and TTS-4 receivers

Lejba P., Nawrocki J., Schillak S., Lemański D., Lehmann M., Nogaś P.

Artificial Satellites : Journal of Planetary Geodesy

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2011

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Vol. 46, No. 4

151--163

EN

This paper concerns determination of clock readings and position of two geodetic receivers: TRIMBLE NetRS and TTS-4, connected to the same antenna of Dorne Margolin choke ring type (IGS BOR1 point) with the usage of precise point positioning (PPP) technique. The TTS-4 receiver was constructed and provided with its software by the time and frequency team from Borowiec Astrogeodynamical Observatory (AOS). Parameters of the receiver clocks and antenna coordinates were determined for the period from 1 to 30 April 2011. The collected data in RINEX format include code and phase observations from GPS constellation recorded with 30 second interval. The computed positions of the antenna based on RINEX data files from TRIMBLE NetRS and TTS-4 receivers are practically the same. The differences of estimated coordinates are from 0.6 to 1.6 mm. However, the accuracy of the clock parameters computed for TRIMBLE NetRS receiver are by one order lower than for TTS-4. It means that TRIMBLE NetRS receiver synchronized with internal quartz oscillator can not be used for timing applications. Currently the AOS laboratory works on the realization and development of the PPP method are in progress. Ultimately, the method will allow very precise comparison of atomic clocks and atomic time scales over great distances based on GNSS phase measurements. This method will increase the quality of comparisons of the atomic time scales carried out in the world, as well as, significantly strengthen the quality of the Polish Atomic Time Scale - TA (PL).

9

Precise Point Positioning in the airborne mode

El-Mowafy A.

Artificial Satellites : Journal of Planetary Geodesy

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2011

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Vol. 46, No. 2

33--45

EN

The Global Positioning System (GPS) is widely used for positioning in the airborne mode such as in navigation as a supplementary system and for geo-referencing of cameras in mapping and surveillance by aircrafts and Unmanned Aerial Vehicles (UAV). The Precise Point Positioning (PPP) approach is an attractive positioning approach based on processing of un-differenced observations from a single GPS receiver. It employs precise satellite orbits and satellite clock corrections. These data can be obtained via the internet from several sources, e.g. the International GNSS Service (IGS). The data can also broadcast from satellites, such as via the LEX signal of the new Japanese satellite system QZSS. The PPP can achieve positioning precision and accuracy at the sub-decimetre level. In this paper, the functional and stochastic mathematical modelling used in PPP is discussed. Results of applying the PPP method in an airborne test using a small fixed-wing aircraft are presented. To evaluate the performance of the PPP approach, a reference trajectory was established by differential positioning of the same GPS observations with data from a ground reference station. The coordinate results from the two approaches, PPP and differential positioning, were compared and statistically evaluated. For the test at hand, positioning accuracy at the cm-to-decimetre was achieved for latitude and longitude coordinates and doubles that value for height estimation.

10

Performance of open source Precise Point Positioning software using single-frequency GPS data

Satirapod C., Kriengkraiwasin S.

Artificial Satellites : Journal of Planetary Geodesy

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2006

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Vol. 41, No. 2

79--86

EN

This research aims to assess the performance of GPS Precise Point Positioning (PPP) with code and carrier phase observations from L1 signal collected from geodetic GPS receiver around the world. A simple PPP software developed for processing the single frequency GPS data is used as a main tool to assess a positioning accuracy. The precise orbit and precise satellite clock corrections were introduced into the software to reduce the orbit and satellite clock errors, while ionosphere-free code and phase observations were constructed to mitigate the ionospheric delay. The remaining errors (i.e. receiver clock error, ambiguity term) are estimated using Extended Kalman Filter technique. The data retrieved from 5 IGS stations located in different countries were used in this study. In addition, three different periods of data were downloaded for each station. The obtained data were then cut into 5-min, 10-min, 15-min and 30-min data segments, and each data segment was individually processed with the developed PPP software to produce final coordinates. Results indicate that the use of 5-min data span can provide a horizontal positioning accuracy at the same level as a pseudorange-based differential GPS technique. Furthermore, results confirm effects of station location and seasonal variation on obtainable accuracies.