Browsing by Author "Alcay, S."

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    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
    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