Journal: GPS Solutions

Abbreviation

GPS Solut

Publisher

Springer

Journal Volumes

ISSN

1521-1886
1080-5370

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Publications1 - 10 of 20
  • Geometry of GPS dilution of precision: revisited
    Item type: Journal Article
    Santerre, R.; Geiger, A.; Banville, S. (2017)
    GPS Solutions
  • Low-degree earth deformation from reprocessed GPS observations
    Item type: Journal Article
    Fritsche, Mathias; Dietrich, R.; Ruelke, A.; et al. (2010)
    GPS Solutions
  • Geometry of GPS relative positioning
    Item type: Journal Article
    Santerre, Rock; Geiger, Alain (2018)
    GPS Solutions
  • Reliability checking for GNSS baseline and network processing
    Item type: Journal Article
    Wieser, Andreas (2004)
    GPS Solutions
  • Enhanced real-time global ionospheric maps using machine learning
    Item type: Journal Article
    Iten, Marcel; Mao, Shuyin; Pan, Yuanxin; et al. (2025)
    GPS Solutions
    Global ionospheric maps (GIM) are commonly used ionospheric products in high-precision Global Navigation Satellite System (GNSS) applications. To meet the increasing demand for real-time (RT) applications, the International GNSS Service (IGS) officially started a real-time service in 2013. One of the tasks of the real-time service is the calculation of real-time GIMs. However, the accuracy of current real-time GIMs is still significantly worse than that of the final GIMs, which are the most accurate ionospheric products but have a latency of several days. The IGS RT GIMs exhibit an RMSE of around 3.5-5.5 total electron content units (TECU) compared to the final GIMs. This study focuses on improving the accuracy of existing real-time GIMs through machine learning (ML) approaches, specifically convolutional neural networks (CNN) and conditional generative adversarial networks (cGAN). We apply our method to the IGS combined real-time GIMs and to Universitat Polit & egrave;cnica de Catalunya (UPC) GIMs. We consider over 130'000 pairs of real-time and final GIMs. Over a 3.5-month test period, the proposed approach shows promising results with a reduction of more than 30% in mean absolute error for the real-time GIMs. Especially for regions with high VTEC values, we find a significant improvement of nearly 50%. The ML-enhanced real-time GIMs also exhibit improved positioning performance for single-frequency GNSS positioning with reductions in the 3D error up to 21 cm. Overall, our proposed method demonstrates great potential in generating more accurate and refined real-time GIMs.
  • A data archive of GPS navigation messages
    Item type: Journal Article
    Beyerle, Georg; Ramatschi, Markus; Galas, Roman; et al. (2009)
    GPS Solutions
  • Detecting slow slip events in the Cascadia subduction zone from GNSS time series using deep learning
    Item type: Journal Article
    Wang, Ji; Chen, Kejie; Zhu, Hai; et al. (2024)
    GPS Solutions
    Slow Slip Events (SSEs) are like long-duration slow earthquakes during which stress is gradually released over several days to months, and a comprehensive catalog of SSEs is essential for a better understanding of the earthquake cycle. However, SSEs usually only produce mm to cm surface deformations, making them a challenge to identify from raw Global Navigation Satellite System (GNSS) time series, which are often obscured by low-frequency background noise. We devise an approach that first employs variational Bayesian Independent Component Analysis to improve the signal-to-noise ratio of GNSS time series and then utilizes deep learning combining bidirectional Long Short-Term Memory and two different attention mechanisms to identify SSEs. We apply this new method to the GNSS three-component time series at 240 stations along the Cascadia subduction zone from 2012 to 2022. A total of 56 SSEs are detected, 18 more than the number in the existing SSEs catalogs during the same period. The starting time, duration, spatial and propagation pattern of the 56 SSEs are consistent with the tremor catalog, which helps to gain new insights into the slip behavior in the Cascadia subduction zone. In general, our work provides an effective framework for extracting subtle signals hidden in GNSS time series.
  • GNSS attitude determination with non-synchronized receivers and short baselines onboard a spacecraft
    Item type: Journal Article
    Willi, Daniel; Rothacher, Markus (2017)
    GPS Solutions
    A new algorithm for global navigation satellite system attitude determination onboard a spacecraft was developed. A distinct feature of the algorithm is the extrapolation of the measurements to a common epoch within a Kalman filter. The necessity for the extrapolation arises from the usage of non-synchronized low-cost receivers. The extrapolation terms typically range from –6 to +6 m for u-blox receivers. Thus, no solution can be obtained without a proper extrapolation. A validation was carried out with synthetic data as well as with signal simulator data. The algorithm delivers an attitude estimation with an accuracy below 1° for three orthogonal baselines of 10 cm length. In conclusion, the algorithm is proven to work, offering a very efficient method of attitude determination onboard a spacecraft.
  • Resilient strategies for static and kinematic PPP-RTK under ionospheric disturbance
    Item type: Journal Article
    Lyu, Sijie; Xiang, Yan; Wang, Ningbo; et al. (2026)
    GPS Solutions
    Precise point positioning real-time kinematic (PPP-RTK) is regionally instantaneous ambiguity-resolution enabled precise point positioning (PPP) with the aid of precise atmospheric corrections. However, obtaining precise ionospheric corrections becomes challenging especially under ionospheric disturbance, potentially degrading the solution even with augmentation. To address this issue, this paper aims to propose a satellite-specific ionospheric residual integrity monitoring (IRIM) index, which is broadcasted along with a grid-based slant ionospheric map to describe the uncertainty of ionospheric corrections. The uncertainty corresponds to the 95% quantile of modeling residuals of reference stations. Besides, three strategies in the user end are utilized to reduce the dependence on external ionospheric information: selective ionospheric correction usage (Strategy S), variance adjustment regarding the IRIM index (Strategy I), and prediction of ionospheric corrections (Strategy P). To validate the performance of the proposed method, both static and kinematic positioning tests are carried out. In static mode, employing all three strategies makes the positioning resilience of PPP-RTK comparable to PPP-AR. Compared to the original PPP-RTK, horizontal and vertical positioning accuracies improve by 86.9% and 78.7%, respectively. As for the kinematic test conducted in challenging environments, the proposed strategies lead to the best positioning results. Notably, the percentage of horizontal errors below 0.2 m increased significantly from 68.7% to 84.6% when compared to the conventional PPP-RTK. Similarly, the improvement ranges from 53.2% to 79.0% in the vertical direction.
  • Robust combination of IGS analysis center GLONASS clocks
    Item type: Journal Article
    Chen, Kangkang; Xu, Tianhe; Yang, Yuanxi (2017)
    GPS Solutions
Publications1 - 10 of 20