H2020 COREGAL Project: Combined Galileo code receiver for positioning and reflectometry for forest management

COREGAL developed a low-cost unmanned aerial platform and service for biomass mapping that will enable large-scale mapping in the Brazilian context of forest management. A first-of-its-kind Galileo Position-Reflectometry receiver has been developed as the primary sensor for platform positioning and biomass estimation. The latter uses reflected Global Navigation Satellite System (GNSS) signals (also called GNSS-R) propagated through tree canopies, branches, and leaves. The GNSS-R concept is that of a bistatic radar, where the transmitter is a GNSS satellite and the receiver can receive both the signal coming directly from the source and the signal reflected from the Earth's surface. While the properties of GNSS signals have been optimized for navigation applications, the reflected signals contain information about the state of the reflecting surface.

Aerial platforms also provide high-precision (centimeter-level) positioning products, which is challenging for remote areas where supporting ground-based GNSS infrastructure is unavailable, as is the case in many forests in Brazil. However, Galileo AltBOC E5 signals offer unprecedented pseudorange measurement quality that can be used for high-precision positioning. An unmanned aerial vehicle (UAV) is equipped with a COREGAL receiver and optical cameras for aerial mapping and biomass estimation, enabling large-scale, low-cost mapping. UAV aerial mapping is at least an order of magnitude lower in cost than manned aerial missions, while GNSS-R can be viewed as a bistatic RADAR that replaces expensive, heavy, and power-hungry radars. Integrating positioning and reflectometry into a single device within a UAV offers a unique value proposition where Galileo and GPS combine uniquely to increase the number of reflected signals and the quality of positioning.

Furthermore, the properties of the GNSS-R signal allow for lower saturation in signal backscatter compared to traditional RADAR systems, enabling greater sensitivity to higher biomass applicable to Brazilian forests. A business plan and model, as well as a market study, have been developed, and legal and regulatory aspects have been considered. The project's results have been widely disseminated. Results have been presented at various conferences, journals, and events, as well as in a webinar aimed at the Brazilian community. The project website has been updated with the results and events. Test campaigns have been conducted to validate the COREGAL platform and approach with promising results, including comparison and combination with satellite data to improve the accuracy of local biomass maps.

Due to insufficient field data, synthetic GNSS-R data had to be generated. While they did not replace the final data, they allowed the necessary research to be conducted with a high degree of confidence. These maps were subsequently converted into carbon maps, enabling improvements in carbon cycle modeling with far-reaching implications. The entire processing chain and methodology were exercised, enabling the concept to be demonstrated as part of a service that will be offered commercially and can be expanded to other countries.

As a key outcome of COREGAL, the consortium recommends further field testing to consolidate the results, confirm some of the assumptions, and gain further operational experience. This was already planned in the business plan, where a phase 0 would include recruiting the first beta users. The consortium considers the COREGAL solution a promising approach that will enable substantial cost reductions and high-precision biomass maps, accelerating the adoption of Galileo-based technology in Brazil and in forested regions around the world. Therefore, the consortium is committed to taking the next steps to continue implementing and commercializing the concept.