Project Counters Ionospheric Disturbance for GNSS

The monitoring station in Brazil uses a Septentrio PolaRxS receiver to monitor the ionosphere, a Septentrio AsteRx3 to perform tests static and kinematic tests, and three RTK Altus APS3 receivers (one as a base station and two as rovers.)

After 27 months of intensive research, a project team funded under the European Union’s 7th Framework Programme has come up with a solution to counter the problem of ionospheric disturbance affecting GNSS signals.

The CALIBRA project recently showcased a commercially applicable approach to mitigate the phenomenon’s impact on high-accuracy GNSS positioning techniques. In  two demonstrations, the project’s newly developed algorithm was successfully tested in actual precision agriculture and offshore operations.

Solar flares can cause ionospheric disturbance, a sudden increase in radio-wave absorption that often delays the propagation of signals and ultimately affects positioning. The problem has kept researchers busy for years.

The CALIBRA project team has been participating in this global research effort by focusing on Brazil, which is one of the most exposed regions due to its proximity to the magnetic equator. Add to this that the sun is at its peak of activity since it entered its new 11-year cycle in 2010.

The project achieved three main milestones. First, the team confirmed that ionospheric scintillation and variations in total electron content (TEC) had a direct impact on the functioning of high accuracy GNSS techniques, such as Precise Point positioning (PPP) and real-time kinematic (RTK) positioning. Then a suitable metric was established to characterize these ionospheric disturbances. Finally, the project produced a short-term empirical model for forecasting TEC and scintillation. A regional TEC map was developed which proved advantageous for use in Brazil and, to counter scintillation, a number of approaches for the mitigation of this phenomenon were proposed and their benefit demonstrated.

The project exploited the CIGALA-CALIBRA network and database — a network of ionospheric scintillation monitor receivers with a web interface (the ISMR Query tool), which collects more than 10 million observations on GPS, GLONASS, Galileo, BeiDou and other global navigation systems every day. Since it was launched in December 2014, this data has helped assist users from more than 20 countries because of the software’s visualization and mining techniques.

In light of this success, CALIBRA partners INGV (Istitute Nazionale di Geofisica e Vulcanologia) filed a patent for their forecasting model, and a new spin-off company — SpacEarth Technology — was set up. SpacEarth’s main purpose is to secure the software’s commercialization in relevant applications and services, while also improving and adapting it to evolving market needs.

The project’s results promise to considerably reduce downtime and financial losses caused by ionospheric disturbance in Brazil and other regions of the world. Learn more about the project here.

Another ionospheric mitigation project was presented at the European Navigation Conference earlier this month.