Concept for Ionospheric-Scintillation Mitigation for Professional GNSS in Latin America
Background & Objectives
‘When the solar winds come around, you’d better hang onto your GNSS receiver, not your hat. That’s because satellite signals propagating through the Earth’s atmosphere can be profoundly affected when the Sun acts up, as it does periodically in 11-year cycles – the upward trajectory of which is just beginning.’ J. Kunches, NOAA, in Inside GNSS.
Solar-induced drifting ionospheric electron-density irregularities may lead to the scintillation of trans-ionospheric GNSS signals. Scintillations not only degrade signal quality but also cause loss-of-lock, posing a major threat to GNSS-based applications demanding high levels of accuracy, availability and integrity. The problem is particularly acute in low latitude areas and will be exacerbated around the next solar maximum, predicted for 2013. Brazil will be particularly exposed, as its territory encompasses the magnetic equator as well the equatorial anomaly ionosphere.
Latin America’s growing reliance on GNSS-based techniques in support of activities such as onshore and offshore surveying, precision farming, geodesy and construction places this region in a particularly vulnerable position. This was demonstrated during the latest major solar storm in 2003, which led to delays or cancellations of major surveying and drilling operations as well as serious perturbations of the American WAAS system with significant economical loss.
The challenge to achieve the CIGALA objectives is to understand the causes of ionospheric disturbances, model their effects and develop novel countermeasure techniques. The project will achieve this goal by:
- studying the market needs and end-user requirements locally in one of the regions most affected, addressing the whole spectrum of GNSS users;
- researching deeply into the underlying causes of ionospheric scintillation and developing state-of-the-art models capable of predicting signal propagation and tracking perturbations;
- carrying out field measurements through the deployment of multi-frequency Galileo-capable receivers, in close collaboration with local academic and industrial partners;
- complementing these measurements through access to archive as well as simulated data;
- designing and implementing novel scintillation countermeasures and associated mitigation techniques;
- field testing the newly developed techniques, and leveraging the same partnership and measurement infrastructure as during the measurement campaign.
Both the initial phase of the measurement campaign and the final field testing and demonstration of the newly developed scintillation mitigation techniques will be held across different fields of GNSS applications that are highly relevant in the geographic area, and will be done in close collaboration with the local partners.
The CIGALA project will tackle the substantial technical and economical threat that the rising of the solar cycle poses to professional GNSS activities taking place in Latin America. CIGALA aims to develop and test ionospheric scintillation mitigation approaches to be implemented in professional multi-frequency GNSS receivers, providing a timely competitive advantage in the Latin American market. In order to achieve this, the project will leverage research and development activities coordinated between leading European and Brazilian experts, and will set up a wide-scale measurement and test campaign at several locations in Brazil during the period of increased solar activity. The most affected local GNSS users will be involved in the assessment of the threat and countermeasures in order to promote greater awareness of the problem and the solutions proposed.
Work performed & results
CIGALA’s technical results are expected to significantly advance the state-of-the-art in understanding climatological signal perturbation and tracking dynamic aspects of strong ionospheric scintillation events affecting GNSS signals and receivers.
Existing climatological scintillation models (such as WBMOD, GISM and WAM) and classical GNSS-receiver tracking models will be further developed and validated by field measurements.
Secondly, a repository of scintillation event records will be established, which will also provide data for GPS legacy signals in L1 band as well as for newly available modernised GPS (L2C, L5) and Galileo signals (E1, E5a, E5b, E5 AltBOC). Leveraging both modelling and field measurement efforts, receiver-level countermeasures will be enabled in Septentrio’s receiver products, strengthening their capability to track GNSS signals and delivering the required accuracy in the presence of moderate to strong scintillation, thus providing Europe with a strong competitive advantage in the Latin American market.
Finally, a targeted dissemination effort will ensure visibility and awareness about the threats posed by the forthcoming high of the solar cycle and the developed countermeasures to the GNSS and Space Weather research communities, as well as to key industrial stakeholders in Latin America.