The research scope of this reprint mainly focuses on GNSS data processing methods; GNSS applications; precise GNSS positioning and navigation; theories, models, and methods for processing wojGNSS ...errors; multi-GNSS positioning technologies; positioning and navigation methods under challenging environments; and low-cost GNSS positioning and navigation.
Penelitian ini bertujuan untuk membandingkan ketelitian data koordinat tiga dimensi pengukuran GNSS dengan metode Network Real-Time Kinematik (NRTK), Real-Time Kinematik Precise Point Positioning ...(RTK-PPP) dan Precise Point Positioning (PPP) secara post-processing. Metode penelitian dilakukan dengan membandingkan data posisi tiga dimensi dari enam titik pengamatan yang masing-masing dwiukur menggunakan setiap metode pengukuran GNSS tersebut. Metode NRTK dilakukan dengan menggunakan stasiun Continuously Operating Reference Station (CORS) milik Badan Informasi Geospasial (BIG), metode RT-PPP dilakukan dengan menggunakan layanan koreksi secara Real-Time dari Trimble Center Point RTX, Adapun metode PPP pengolahan data dilakukan dengan memanfaatkan layanan Trimble CenterPoint RTX Post-Processing. Analisis data dilakukan dengan membandingkan data posisi horizontal serta data tinggi dengan setiap metode pada setiap titik pengamatan. Analisis data juga dilakukan pada waktu pengamatan yang dibutuhkan pada metode NRTK dan RT-PPP untuk mencapai ketelitian tiga dimensi di bawah 5 cm. Hasil penelitian menunjukkan bahwa terdapat perbedaan rata-rata pada posisi horizontal untuk setiap metode sebesar 0.224 m di sumbu easting dan 0.096 m di sumbu northing. Adapun untuk data tinggi perbedaan rata-rata terbesar adalah pada metode NRTK yang dibandingkan dengan metode PPP ITRF 2008 dan 2014 yaitu sebesar 0.255 m dan perbedaan rata-rata terkecil adalah pada metode NRTK yang dibandingkan dengan metode RT-PPP yaitu sebesar 0.077 m. Terkait dengan waktu pengamatan, pada metode NRTK, waktu yang diperlukan untuk mencapai ketelitian yang stabil < 5 cm pada lokasi pengamatan yang bebas obstruksi memerlukan waktu kurang dari satu menit, sedangkan pada metode RT-PPP, waktu yang diperlukan memerlukan waktu dengan kisaran antara 11 hingga 20 menit.
BeiDou Global Navigation Satellite System (BDS-3) provides a regional Precise Point Positioning (PPP) service, called PPP-B2b, for users in China and surrounding areas through B2b signal transmitted ...from its three geostationary earth orbit (GEO) satellites. The information broadcasted by the B2b signal include satellite orbit corrections, satellite clock offset corrections, and differential code bias (DCB) corrections of BDS-3 satellites. In this study, the accuracies of PPP-B2b corrections along with real-time PPP performance are comprehensively evaluated referenced to precise orbit and clock products from GFZ and the precise DCB products from CAS. The result indicates that the accuracy of the BDS-3 broadcast orbit is similar to that of the PPP-B2b real-time orbit. The PPP-B2b clock offset correction improved the satellite clock offset precision of the BDS-3 broadcast ephemeris. The Signal-in-Space Range Error (SISRE) of broadcast ephemeris and PPP-B2b are calculated, which are 0.536 and 1.24 m, respectively. The large SISRE value of PPP-B2b is caused by the satellite-specified systematic bias to IGS final products. The positioning performance evaluation of real-time PPP with B2b service is carried out and compared with the real-time product provided by Wuhan University (WHU) based on the eight IGS MGEX stations in China and surrounding countries. The positioning accuracy of static positioning mode with PPP-B2b service achieved centimeter-level accuracy in the selected station, and that of kinematic positioning mode achieved decimeter-level accuracy. The availability rate of PPP-B2b corrections in the surrounding area of China, however, degrades from 88.76% to 60.91% in the selected stations. The accuracy of the PPP solution using PPP-B2b correction is better than that of using WHU real-time product within China. The positioning performance of stations located at the boundary of the PPP-B2b service area, however, is affected by the number of PPP-B2b available satellites. The positioning accuracy in kinematic positioning mode is worse than that of using WHU real-time precise product.
Precise point positioning (PPP) has been used for decades not only for general positioning needs but also for geodetic and other scientific applications. The CNES-CLS Analysis Centre (AC) of the ...International GNSS Service (IGS) is performing PPP with phase ambiguity resolution (PPP-AR) using the zero-difference ambiguity fixing approach also known as “Integer PPP” (IPPP). In this paper we examine the postprocessed kinematic PPP and PPP-AR using Galileo-only, GPS-only and Multi-GNSS (GPS + Galileo) constellations. The interest is to examine the accuracy for each GNSS system individually but also of their combination to measure the current benefits of using Galileo within a Multi-GNSS PPP and PPP-AR. Results show that Galileo-only positioning is nearly at the same level as GPS-only; around 2–4 mm horizontal and aound 10 mm vertical repeatability (example station of BRUX). In addition, the use of Galileo system—even uncompleted—improves the performance of the positioning when combined with GPS giving mm level repeatability (improvement of around 30% in East, North and Up components). Repeatabilities observed for Multi-GNSS (GPS + GAL) PPP-AR, taking into account the global network statistics, are a little larger, with 8 mm in horizontal and 17 mm in vertical directions. This result shows that including Galileo ameliorates the best positioning accuracy achieved until today with GPS PPP-AR.
High-precision positioning from Global Navigation Satellite Systems (GNSS) has garnered increased interest due to growing demand in various applications, like autonomous car navigation and precision ...agriculture. Precise Point Positioning (PPP) offers a distinct advantage over differential techniques by enabling precise position determination of a GNSS rover receiver through the use of external corrections sourced from either the Internet or dedicated correction satellites. However, PPP’s implementation has been challenging due to the need to mitigate numerous GNSS error sources, many of which are eliminated in differential techniques such as Real-Time Kinematics (RTK) or overlooked in Standard Point Positioning (SPP). This paper extensively reviews PPP’s error sources, such as ionospheric delays, tropospheric delays, satellite orbit and clock errors, phase and code biases, and site displacement effects. Additionally, this article examines various PPP models and correction sources that can be employed to address these errors. A detailed discussion is provided on implementing the standard dual-frequency (DF)-PPP to achieve centimeter- or millimeter-level positioning accuracy. This paper includes experimental examples of PPP implementation results using static data from the International GNSS Service (IGS) station network and a kinematic road test based on the actual trajectory to showcase DF-PPP development for practical applications. By providing a fusion of theoretical insights with practical demonstrations, this comprehensive review offers readers a pragmatic perspective on the evolving field of Precise Point Positioning.
Global 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.
This study applies the zero‐differenced integer ambiguity method, named PPP‐Fixed, to extract real‐time ionospheric data and eliminate the latencies of rapid/final Global Ionosphere Maps (GIMs). The ...PPP‐Fixed method is also used to derive ionospheric data for post‐processed GIM generation, named SGG Post‐GIM, combined with low earth orbit satellite data. The obtained hardware delays are applied to revise real‐time ionospheric data. Meanwhile, the estimated multi‐source ionospheric model is regarded as historical data to estimate an ionospheric prediction model for constraint using the semi‐parameter model. Then, the Kalman filter is employed to estimate the parameters to generate real‐time GIM. Finally, the accuracy of estimated real‐time GIM, named SGG RT‐GIM, and SGG Post‐GIM is assessed. During the experimental period, the mean differences of SGG Post‐GIM and SGG RT‐GIM relative to GIMs provided by the international Global Navigation Satellite System service, named IGSG, are −0.46 and −0.57 Total Electron Content Unit (TECU), respectively. The corresponding Root Mean Square (RMS) values are 1.64 and 3.08 TECU. Over the test period, the mean positioning errors of the single‐frequency precise point positioning corrected by IGSG, SGG Post‐GIM, SGG RT‐GIM, and Klobuchar model are 0.14, 0.19, 0.21, and 0.25 m in the horizontal direction, respectively, while the corresponding errors are 0.36, 0.33, 0.38, and 0.64 m in the up direction. Further, the mean biases of experimental days for the self‐consistency assessment are 0.06, −0.01, and −0.07 TECU for IGSG, SGG Post‐GIM, and SGG RT‐GIM, respectively. The corresponding RMS values are 1.19, 1.15, and 1.57 TECU.
Plain Language Summary
As there are latencies of final Global Ionosphere Maps (GIMs) and rapid GIMs, we generate real‐time GIM by the ionospheric data extracted from the zero‐differenced integer ambiguity method, named PPP‐Fixed. The PPP‐Fixed method is also adopted to derive ionospheric data for post‐processed GIM generation, named SGG Post‐GIM, combined with low earth orbit ionospheric data. The obtained satellite and receiver differential carrier‐phase hardware delays are employed for real‐time ionospheric data correction, obtaining bias‐free real‐time ionospheric data. Meanwhile, the semi‐parameter model is applied to estimate an ionospheric prediction model for constraint based on the historical ionospheric model estimated by multi‐source data. Finally, the Kalman filter is employed to estimate the parameters for real‐time GIM generation, named SGG RT‐GIM. The accuracy of estimated SGG RT‐GIM and SGG Post‐GIM is evaluated. The assessed results indicated that the accuracy of SGG RT‐GIM is slightly worse than that of GIMs provided by the international Global Navigation Satellite System service, named IGSG, while that of SGG Post‐GIM is slightly better than IGSG.
Key Points
The final and rapid Global Ionosphere Map (GIM) cannot meet the demand for real‐time ionosphere monitoring and ionospheric delay corrections
The real‐time ionospheric data derived from the PPP‐Fixed method are employed to generate real‐time GIMs combined with Global Navigation Satellite System (GNSS) and low earth orbit satellite data
The differences between estimated real‐time GIM and GIMs provided by the international GNSS service mainly appeared in the equatorial region
Recent advances in testing for the validity of Purchasing Power Parity (PPP) focus on the time series properties of real exchange rates in panel frameworks. One weakness of such tests, however, is ...that they fail to inform the researcher as to which cross-section units are stationary. As a consequence, a reservation for PPP analyses based on such tests is that a small number of real exchange rates in a given panel may drive the results. In this paper we examine the PPP hypothesis focusing on the stationarity of the real exchange rates in up to 25 OECD countries. We introduce a methodology that when applied to a set of established panel unit-root tests, allows the identification of the real exchange rates that are stationary. Our results reveal evidence of mean-reversion that is significantly stronger as compared to that obtained by the existing literature, strengthening the case for PPP.
Assessment Of GNSS Positioning Techniques In EGYPT Abd El-rahman Abd El- naeim; Ahmed Elhatab; Marwa Azzam ...
Port-Said Engineering Research Journal (Online),
03/2024, Letnik:
28, Številka:
1
Journal Article
Odprti dostop
This research delves into Global Navigation Satellite Systems (GNSS) positioning accuracy, focusing on GPS, GLONASS, and their combined utility to evaluate GLONASS as an independent system in case ...GPS is down. The study spans three phases. First, data from stations located in Port Said, analyzed using relative positioning technique, GPS shows an average coordinate deviation of 0.32 millimeters for GPS-only scenarios, while GLONASS exhibits 1.045 millimeters for GLONASS-only scenarios. Merging both narrows this gap, especially in shorter baselines. Second, an extensive dataset over three years from eight Egyptian stations, using GPS and GLONASS as references, shows that GPS consistently provides better three-dimensional accuracy in most stations with close values. Finally, employing Precise Point Positioning (PPP) techniques, the study rigorously compares three processing software solutions (PPPH, PPP-ARISEN, PRIDE-PPPAR) with the same dataset. PRIDE-PPPAR closely aligns with BERNESE software accuracy, followed by PPP-ARISEN and PPPH. These findings suggest that GLONASS alone can be used for many applications, and open-source PPP software can be employed with acceptable accuracy.
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