Study on the accuracy of Multi-GNSS PPP for different observing sessions time spans using PRIDE PPP-AR open-source software package

The Galileo constellations are characterized by transmitting GNSS signals on multi-frequencies, which can benefit the robustness and accuracy of the solutions. However, the dual-frequency E1/E5a combinations are generally used for precise point positioning (PPP). In this paper, the performance of Galileo static and kinematic PPP using different dual- and multi-frequency combinations are assessed using observations from the European region. Overall, the accuracy of daily PPP achieved by the dual-frequency GPS, Galileo, and BDS is better than 5 mm in the horizontal direction and better than 10 mm in the vertical direction. Though the number of observed Galileo satellites is less than GPS, the horizontal accuracy can reach 1.6 mm/2.3 mm/5.7 mm on North/East/Up component, which is improved by 59.0% and 12.3% compared to the GPS in the north and up direction. Then, the accuracy of Galileo static PPP is analyzed using different dual- and multi-frequency combinations. Results indicate that the Galileo E1/E5b PPP can degrade the accuracy due to the inter-frequency clock biases between the E1/E5a and E1/E5b combinations. Best accuracy can be achieved for the triple- and four-frequency PPP, which is 4.8 mm in the up direction. The hourly accuracy for the static PPP can reach 5.6 mm/9.2 mm/12.6 mm in the north/east/up direction using the GPS/Galileo/GLONASS/BDS combinations. Finally, a positioning convergence ratio (PCR) indicator, which represents the accuracy of PPP over a period, is used to analyze the convergence time of kinematic PPP. Results indicated that the multi-frequency Galileo observations contribute minorly to the convergence of kinematic PPP. However, Galileo shows the best convergence performance for the single GNSS positioning, and the GPS/Galileo combined PPP achieved the best performance for the PPP using different GNSS combinations.

The study investigated the influence of tropospheric gradients on the accuracy of Precise Point Positioning (PPP), using data from Brazilian Network for Continuous Monitoring of the GNSS Systems (RBMC) in the Amazon and southern regions of Brazil. The research was conducted due to the need to better understand how tropospheric gradients affect the accuracy of kinematic PPP. Understanding these effects is crucial to improving the accuracy of Global Navigation Satellite System (GNSS) positioning, especially in regions with variable atmospheric conditions. The study used RBMC data and tropospheric delay modeling based on Numerical Weather Prediction (PNT) data. The results showed significant improvements in the planimetric accuracy of kinematic PPP with the inclusion of tropospheric gradients. The improvements were observed on the order of millimeters, with increases of up to 3% in horizontal accuracy and 7% in vertical accuracy. The analysis also revealed that estimating tropospheric gradients was more significant in the vertical component and regions with higher humidity tropospheric scenarios. It was concluded that including tropospheric gradients is crucial to improving the accuracy of kinematic PPP, especially in the Amazon region, where tropospheric scenarios are more humid. Additionally, estimating tropospheric gradients was considered as or even more significant in planimetric accuracy than using a Mapping Function based on PNT data. This research highlights the importance of considering tropospheric gradients in GNSS positioning and provides valuable insights for future studies and practical applications in the field of geodesy and satellite navigation.

The use of the Precise Point Positioning (PPP) technique has become very advantageous with the development of GNSS positioning technology. It is possible to get highly accurate position information without the need of any reference station data using the PPP technique. However, there are various factors that affect the accuracy of PPP solutions, including the initial phase ambiguity solution type, which can be fixed or float, atmospheric effects, observation length, used satellite systems, and used precise products. The Canadian Spatial Reference System-Precise Point Positioning (CSRS-PPP) service, one of the online PPP services, was updated on October 20th, 2020, and upgraded to version 3, capable of the Ambiguity-Fixed (PPP-AR) solution. Prior to this date, the service had offered the Ambiguity-Float (PPP-Float) solution. In this study, it is aimed to investigate the effect of using different satellite systems (GPS, GPS&GLONASS), length of observation time, static/kinematic processing modes, and initial phase ambiguity solution types on PPP accuracy. The daily observation data of ANKR, ISTA, IZMI, MERS, and KRS1 IGS GNSS stations located within the borders of Türkiye, divided into different sub-sessions (1-hour, 2-hours, 4-hours, 8-hours, and 12-hours) were processed using CSRS-PPP web-based service as PPP-Float before the update and PPP-AR after the update. As a result of the comparison, the combined use of GPS & GLONASS satellite systems instead of using GPS satellites alone has increased horizontal and vertical accuracy in both static/kinematic PPP-Float and PPP-AR solutions. Considering the static solutions, horizontal and vertical position accuracies increase as the observation time increases in both ambiguity solution methods using different constellations. In the case of comparison of the ambiguity solution methods, it was found that the PPP-AR approach offered higher accuracy than the PPP-Float in all solution cases.

Precise Point Positioning (PPP) is a modern satellite-based technique known for its simplicity, efficiency, and cost-effectiveness, eliminating the need for a reference or base station. This study evaluates the accuracy of Precise Point Positioning (PPP) solutions for both static and kinematic observations using the CSRS-PPP service. To ensure a fair comparison, PPP-derived results were assessed against relative positioning techniques. Field measurements, including static and kinematic data, were collected across a 39 km² study area in northern Egypt to generate topographic contour maps. The findings indicate that PPP is a viable alternative for static positioning, achieving a 2D horizontal accuracy of ±2.54 cm, though vertical accuracy is lower at 11.3 cm. In kinematic mode, horizontal accuracy is ±5 cm, while vertical accuracy decreases to 18.4 cm. While the achieved 2D accuracy meets the needs of most environmental applications, the lower height precision may not be suitable for tasks requiring high vertical accuracy.

Assessing the contribution of Galileo to GPS+GLONASS PPP: Towards full operational capability

Precise Point Positioning (PPP) is increasingly being used for achieving highly accurate positioning using a single GNSS receiver, particularly in applications such as seismic monitoring and structural health assessments. This study explores the impact of GNSS data sampling rates on PPP accuracy and convergence time by collecting field measurements from five observation points in Erbil, Iraq, using a Leica GS16 instrument. Data were recorded at sample intervals of 5, 15, 30, and 60 seconds for two hours at each location. Statistical analysis shows that reducing the sampling interval significantly improves the root mean square error (RMSE). For example, at the 5-second sampling rate, the RMSE at point A dropped by 85%—from 0.35 meters at 15 minutes to 0.05 meters after 120 minutes. Similarly, at the 60-second sampling rate, the RMSE improved by approximately 80% during the same period. Across all points, the highest accuracy improvements occurred within the first 30 to 60 minutes of observation, demonstrating that higher sampling rates help reduce convergence times. However, the benefit diminishes for extended observation durations, suggesting that optimizing the sampling interval is crucial for balancing accuracy and efficiency in PPP applications.

Precise point positioning with quad-constellations: GPS, BeiDou, GLONASS and Galileo

Precise Point Positioning (PPP) algorithms have been widely used in the Global Positioning System (GPS)-based applications. A PPP technique with a single receiver provides effective solutions where accurate absolute positioning is required. This paper provides the performance assessment of GPS PPP for detecting the displacements caused by an earthquake. For this purpose, the earthquake that occurred on 21 July 2017 at Kos-Bodrum with the impact of Mw 6.6 was investigated by analyzing the data of the permanent GPS stations located around the related region with the PPP technique. The location distances of these GPS stations range from 10 to 89 km to the epicenter of this earthquake. GPS data provided from seven permanent stations from the Continuously Operating Reference Stations-Turkey (CORS-TR) and local Bodrum CORS networks were processed to determine the co-seismic displacements during the earthquake. The data of these stations for days of year (DOYs) 200, 201, 202, and 203 were analyzed with post-process static PPP and kinematic PPP methods. GIPSY-OASIS II v6.4 was used for processing the data and all of the solutions were performed in the ITRF2008 reference frame. Two strategies were followed on the post-process static solutions. In the first strategy, 4-day data with 24-h observations were separately analyzed day by day. In the second strategy, the 24-h data were divided into 3-h duration, which is the minimum duration for optimum PPP solutions, and then the analyses were performed. When the displacements between DOYs 200 and 203 are considered in the 24-h data analysis, significant displacements have been observed through northwest direction in the northern stations whereas MUG1 is excluded. Moreover, there is significant displacement through the southeast direction in the station DATC located in the south of the epicenter. When the 3-h solutions are examined, displacements, especially on n and e directions, are observed starting from the solutions, which include Mw 6.6 earthquake. According to the kinematic PPP solutions, the effects of the Mw 6.6 earthquake can be seen clearly in the stations DATC, ORTA, TRKB, and YALI. Considering all outcomes, the PPP technique with both static and kinematic solutions provides effective results for detecting the displacements during the earthquake.

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.

A new precise point positioning (PPP)-B2b augmentation service broadcast by the BeiDou Navigation Satellite System (BDS-3) geosynchronous Earth orbit (GEO) satellite can provide real-time and high-precision orbit and clock offset corrections for global navigation satellite system (GNSS) users in China and its surrounding areas. It has great significance and research value for real-time and high-precision positioning applications. First, orbit, clock offset, and differential code bias (DCB) of PPP-B2b products are evaluated. Second, the influence of PPP-B2b service on the enhanced positioning of single-frequency (SF), dual-frequency (DF), and Multi-Frequency (MF) real-time PPP using 30 days of BDS-3 observations is verified. The result shows that the standard deviation (STD) of clock offset and the root mean square (rms) of orbit in the 3-D direction for medium Earth orbit (MEO) satellites are 0.118 ns and 0.286 m, respectively, which is 75.9% and 18.3% higher than that of broadcast ephemeris. The statistical results show that the median positioning accuracy of static SF PPP, DF PPP, and MF PPP is better than 0.20/0.09/0.08 m, and the convergence time is better than 51/10/8 min. The median positioning accuracy of kinematic SF PPP, DF PPP, and MF PPP is better than 0.40/0.12/0.12 m, and the convergence time is better than 145/16/12 min. Using the PPP-B2b products, the positioning accuracy of DF PPP and MF PPP is comparable and close to that of DF PPP using the precise products, while the convergence time of MF PPP is improved by 24.8% and 27.7% over DF PPP in static and kinematic solutions, respectively.

window.dataLayer = window.dataLayer || []; function gtag(){dataLayer.push(arguments);} gtag("js", new Date()); gtag("config", "UA-72322659-1");

Assessment of the accuracy and convergence period of Precise Point Positioning

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.

The main challenge of dual-frequency precise point positioning (PPP) is that it requires about 30 min to obtain a centimeter level accuracy. Currently, PPP is generally conducted with GPS only using the ionosphere-free combination. Along with the competition of the first phase of the Beidou Navigation Satellite System (BDS) which comprising 5 satellites in Geostationary Orbit (GEO), 5 in Inclined Geosynchronous Orbit (IGSO) and 4 in Medium Earth Orbit (MEO) by the end of 2012, the regional navigation capabilities has been formed and the visibility and availability have been significantly improved for users in the Asia-Pacific regional area. Attention has been paid to improve the performance of PPP by combining BDS and other navigation satellite system (GPS/GLONASS). This study introduces a single-differenced (SD) between-satellite PPP model which can process any single-system or multi-system GNSS (GPS/GLONASS/BDS) raw dual-frequency carrier phase measurements. In this model, the GPS satellite with the highest elevation is selected as the reference satellite to form the SD between-satellite measurements. Thus the GPS receiver clock offset is canceled and only a system time offset between GPS and other GNSS system is estimated for the observations of GLONASS or BDS. In the proposed model, noisy pseudorange measurements are ignored thus modeling the pseudorange stochastic model is not required. The stochastic model for SD measurements and states can be easily realized by mapping that for undifferenced measurements and states. Also the correlation of the SD measurements is considered. Using a 7-day data set from 10 multiple system GNSS stations, we have investigated the performance of single-system PPP, GPS/GLONASS PPP and GPS/GLONASS/BDS PPP, including convergence speed and positioning accuracy. The contribution of BDS observation to the performance of multi-GNSS PPP is analyzed and assessed with special concern. Numerous experimental results indicate that after adding BDS observations, the convergence time can be reduced by 10–12 % for GPS PPP, and reduced by about 5–7 % for GPS/GLONASS PPP further. Besides, BDS observations can contribute to improving the accuracy of kinematic PPP with 3 h observations. After adding BDS observations, the RMS in kinematic mode is improved by 14.3, 7.1 and 7.5 % for GPS PPP while 11.1, 16.7 and 6.5 % for GPS/GLONASS PPP, in the east, north and up directions, respectively. For GPS/GLONASS/BDS PPP, an accuracy of 1–2 cm in horizontal and 2–3 cm in vertical directions can be achieved in kinematic mode while an accuracy of less than 1 cm in horizontal and 1–2 cm in vertical directions can be achieved in static mode.

Hassas Nokta Konumlama (Precise Point Positioning-PPP), tek bir GNSS alıcısıyla hassas uydu yörünge ve saat bilgilerini kullanarak santimetre doğruluğunda konum bilgisi sağlayan bir yöntemdir. Son zamanlarda bu yöntem pek çok bilimsel çalışmaya konu olmaktadır. Bu çalışmada, mevsimlerin PPP konum belirleme doğruluğu üzerindeki etkisini araştırmak amacıyla kuzey yarım kürede yer alan yüksek enlem (KIR8 (İsveç), NYA2 (Norveç)), orta enlem (ANKR(Türkiye), DLF1(Hollanda)) ve ekvatoral bölgede (NKLG(Gabon), SIN1(Singapur)) bulunan Uluslararası GNSS Servisi (International GNSS Service: IGS) istasyonları seçilmiştir. Seçilen istasyonlara ait 365 gün 24 saat 30 saniyelik RINEX verileri çözümlerde kullanılmak üzere elde edilmiştir. 01.12.2019-30.11.2020 tarihleri arasında elde edilen veriler çözümlerin yapılabildiği web tabanlı PPP servislerinden CSRS-PPP, MagicGNSS ve APPS ile değerlendirilmiştir. Web tabanlı servislerden elde edilen koordinatların hassasiyetlerini araştırmak amacıyla her ay için ortalama koordinat değerleri kullanılarak karesel ortalama hatalar (KOH) hesaplanmış, daha sonra mevsimlere bağlı doğrulukları ortaya koymak için istasyonların IGS’den temin edilen bilinen koordinatları kullanılarak konum ortalama hataları hesaplanmıştır. Aynı istasyonlar ve servisler için farklı mevsimlerde elde edilen konum ortalama hataları Bartlett testi ile karşılaştırılmıştır. Karşılaştırma sonunda ANKR istasyonu hariç diğer istasyonlarda konum ortalama hatalarının uyuşum içinde olduğu, konum doğruluklarının mevsimlerden ziyade kullanılan servislere bağlı olduğu ve en iyi sonuçların MagicGNSS ile elde edildiği görülmüştür.