Browsing by Author "Konukseven, C."

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    Article
    Citation - WoS: 13
    Citation - Scopus: 14
    Assessing the Performance of Bds-3 for Multi-Gnss Static and Kinematic Ppp-Ar
    (Elsevier Ltd, 2022) Öğütçu, S.; Alcay, S.; Özdemir, Behlül Numan; Li, P.; Zhang, Y.; Konukseven, C.; Atiz, O.F.
    As of 2021, a total of four different GNSS constellations – namely, GPS, GLONASS, Galileo, and BDS-3 – can be used with Full Operational Capability (FOC). In this work, the contribution of BDS-3 FOC to GPS + GLONASS + Galileo (GRE) PPP-AR is investigated, considering the three different cut-off angles (7°, 30°, and 45°) and different lengths of static observation sessions (24-, 12-, 6-, 3-, 1-, 0.5-, 0.25-hour). The data of 31 IGS-MGEX stations is processed with GRE PPP-AR and GREC3 (GPS + GLONASS (using float mode) + Galileo + BDS-3) PPP-AR modes. The results showed that BDS-3 degraded the horizontal (except for 24-h sessions) and vertical accuracy of static GRE PPP-AR solutions regardless of the elevation cutoff angle and observation time. The kinematic results showed that BDS-3 significantly contributed to the accuracy of GRE kinematic PPP-AR for 30° and 45° cutoff angles. The convergence time analysis showed that BDS-3 only contributes to GRE kinematic PPP-AR for the vertical component. © 2022 COSPAR
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    Article
    Availability Analysis of Gnss Orbit and Clock Files
    (TUBITAK, 2023) Öğütcü, S.; Alçay, S.; Özdemir, B.N.; Konukseven, C.; Atiz, Ö.F.
    Precise point positioning with Global Navigation Satellite Systems (GNSS), orbit and clock products are mandatory. Today, different analysis centers produce satellite orbit and clock products. At the same time, the latency of these products is divided into three different categories. In this study, the satellite availability analysis of the publicly available final, rapid and ultra-rapid orbit (sp3) and clock files were investigated for Global Positioning System (GPS), Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS), European Global Navigation Satellite System (Galileo), BeiDou Navigation Satellite System (Beidou-2, BeiDou-3) and Quasi-Zenith Satellite System (QZSS) satellites within a one-year period of 2021. In addition, clock biases that do not exist in orbit files have also been calculated for each system. The results show that average number of GPS and GLONASS satellites are consistent among the products, however, the average GALILEO and BeiDou satellites are significantly changing among the products. The minimum average number of Galileo satellites was calculated for the final, rapid and ultra-rapid orbit products for the Centre national d'études spatiales (CNES (final)), German Research Centre for Geosciences (GFZ (rapid)) and GFZ (ultra) analysis centers, respectively. The minimum average number of satellites for BeiDou-3 medium earth orbit (MEO) and QZSS was calculated for the CODE analysis center. © 2023, TUBITAK. All rights reserved.
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    Article
    Citation - WoS: 3
    Citation - Scopus: 3
    Gps + Galileo + Bds-3 Medium To Long-Range Single-Baseline Rtk: an Alternative for Network-Based Rtk?
    (Cambridge University Press, 2023) Ogutcu, S.; Alcay, S.; Ozdemir, B.N.; Duman, H.; Koray, U.; Konukseven, C.; Bilal, N.G.
    Thanks to the development of the real-time kinematic (RTK) algorithm and the emerging Global Navigation Satellite System (GNSS), especially for Galileo and BeiDou-3, reliable positioning accuracy for medium and long-baseline RTK became possible globally. Moreover, with the development of the GNSS receiver hardware, baseline length limitations due to radio-based communications are removed thanks to internet-based communication. In this work, single-baseline RTK, incorporated partial ambiguity resolution with troposphere and ionosphere weighting, using GPS (G), Galileo (E), BeiDou-3 (C3) and multi-GNSS (GE and GEC3), is conducted with real GNSS data of EUREF Permanent GNSS network under three different cutoff angles (10°, 20°, and 30°) for six different lengths of baselines (∼50, ∼150, ∼250, ∼350, ∼450, and ∼550 km). The results show that the multi-GNSS RTK solution significantly contributed to the positioning accuracy and convergence time of the single-system RTK solutions. Based on the results, non-available epoch-wise solutions for the high-degree cutoff angles are more obvious for the single-system RTK, whereas multi-GNSS solutions provide 100% solutions for each cutoff angle and baseline. The results indicate that instantaneous and a few epochs single-epoch ambiguity resolution is feasible for 50, 150, 250 and 350 km baseline lengths for multi-GNSS RTK. Based on the positioning results, horizontal-vertical positioning improvements of multi-GNSS RTK (GEC3) compared with the single-system GPS RTK are found as 50%-37%, 40%-35%, 55%-47%, 53%-54%, 57%-49% and 57%-49% for 50, 150, 250, 350, 450 and 550 km, respectively, under a 10° cutoff angle. For 20° and 30° cutoff angles, the accuracy improvements are much higher. The convergence time improvements (n/e/u) of multi-GNSS RTK (GEC3) compared with the single-system GPS RTK are found as 86/92/75%, 77/67/72%, 75/77/83%, 53/56/52%, 69/49/62%, and 52/45/39% for 50, 150, 250, 350, 450 and 550 km, respectively, under a 10° cutoff angle. Copyright © The Author(s), 2023. Published by Cambridge University Press on behalf of The Royal Institute of Navigation.
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    Article
    Citation - WoS: 10
    Citation - Scopus: 12
    Static and Kinematic Ppp-Ar Performance of Low-Cost Gnss Receiver in Monitoring Displacements
    (Elsevier Ltd, 2023) Ogutcu, S.; Alcay, S.; Duman, H.; Ozdemir, B.N.; Konukseven, C.
    Recently, low-cost GNSS receivers have played a significant role in displacement monitoring studies due to the increasing availability of mass-market applications. In this work, the performance of static and kinematic PPP-AR using a low-cost u-blox ZED-F9P GNSS receiver in monitoring displacements is investigated by comparing it with a geodetic-grade GNSS receiver using a displacement simulation apparatus. The capability to determine the horizontal displacement direction is also investigated for both receivers. The results showed that one-sigma horizontal / vertical RMSEs computed from the true displacements and computed displacements are 1.4 / 5.6 mm and 2.6 / 8.4 mm for the geodetic and u-blox receivers, respectively, using 24-h data with static GPS + GLONASS PPP-AR. It is found that GLONASS contribution to GPS-only static PPP is more evident for the u-blox receiver compared with the geodetic one. RMSEs are found to be higher as observation times are decreased. The post-processed kinematic test results showed that minimum 10 / 20 and 20 / 30 mm horizontal / vertical dynamic displacements can be visually detected as an offset from the daily time series for the geodetic and u-blox receivers, respectively. © 2023 COSPAR