Signals Runtime

We all remember the controversies surrounding the giant waves of Nazaré. Since 2011, the Australian surfer Garret McNamara broke a world record when surfing in a 30-meter-high body of water, which, with each new attempt, questions the validity of the measurements of the waves. And in the same week that the sea made news again due to the strength with which it landed, a Portuguese space technology company, Deimos Engenharia, won a European competition and will lead a project to develop a solution that uses similar signals to those of the GPS to make ocean altimetry, to the accuracy of the millimeter.

During this week’s storm, the researcher and specialist in hydraulics at the University of Porto Veloso Gomes complained, in statements to the PUBLIC, about the difficulty of obtaining real-time data on the height of the waves – and other parameters, such as his period of passage. These are measured by probes called ondographs, installed in buoys, a technology that is very susceptible to breakdowns and other problems that leave it inoperable. At the hydrographic institute, Lieutenant Quaresma dos Santos assumed, for example, that the Navy had been waiting for a month for the sea to allow the installation of two buoys that make measurements in Nazaré.

The Hassle of Current Technologies

The problems of current technologies – not very reliable measurement, inconsistency due to sea conditions, and high installation and maintenance costs – are an opportunity for Deimos Engenharia, a partner company of the European Space Agency that has been testing, for some time, Padrão dos Descobrimentos, in Lisbon, an alternative with millimeter precision, regardless of weather conditions and much cheaper. In material terms, it is enough to have, roughly speaking, one or two satellite signal receivers from the various global geolocation systems – the North American GPS, the Chinese BeiDou, the Russian Glonass, and the European Galileo, and two well-tuned antennas. One to receive the signal coming directly from the sky and the other capable of reading the satellite signal reflected by the sea.

Some Facts About GNSS-R Technology

The GNSS-R technology (Reflectometry from Global Navigation Satellite Systems) is in full development, and its use in ocean altimetry is already being tested by Deimos in the SARGO project, funded by the National Strategic Reference Framework, in a partnership with the Hydrographic Institute, an entity that manages the devices placed on the coast in Portugal, and the respective data. The SARGO prototype has been placed in the Padrão dos Descobrimentos, 50 meters high, for sessions to measure the calmer waters of the Tagus using Galileo signals. In tune, you will be able to measure, for example, the waves of the Nazaré canyon, explained one of the people responsible for the project, Nuno Catarino.

The current Research and Development Framework Program will finance 2.8 million euros for this work on the development of GNSS-R technology for Galileo, thus giving the endorsement to the European GNSS-R Environment Monitoring (E-GEM) project, coordinated by Deimos Engenharia, which has as partners ten European entities: the Polytechnic University of Catalonia, the Higher Council for Scientific Research, the University of Salamanca (both in Spain), the French Institute for Research and Exploration of the Sea (Ifremer, France), the Nansen Center for the Environment and Remote Sensing and the Northern Research Institute (Norway), the Department of Civil Engineering and Informatics at the University of Roma Tor Vergata and the Department of Electronics and Telecommunications Engineering at the University La Sapienza (Italy),and the German Research Center for Geosciences (Germany).

Final Thoughts

The use of these devices will not be limited to the waves of the sea. Nuno Catarino adds that the same technology can be used, for example, to measure quantities of biomass in a terrain, combining data from the reflection of the GNSS signals that touch the ground with those reflected by the treetops. Knowing the tree in question, and its normal development, we were able, mathematically, to calculate the mass of vegetation existing in a given place, he explained. In fact, in this project financed by the European Union, in addition to the development of a fixed device, similar to SARGO, it is planned to adapt the technology to an unmanned aerial vehicle (the famous drones) and a micro-satellite that in 2015 will be placed in an orbit 1200 kilometers from the Earth’s surface, well below the 25 thousand kilometers at which the GNSS systems are located.