In the context of transitioning to safer, greener and more cost-efficient aviation operations, the use of GNSS in this domain is increasing. GNSS-based flight procedures provide increased flexibility in procedure design, contributing to a more efficient use of airspace, less fuel consumption and CO2 emissions and cost reduction due to no costs for infrastructure maintenance. However, the vulnerabilities of the GNSS signal and RF interferences may have negative impacts on aircraft operations. 

ECHO project logo

Considering the increased reliance on satellite navigation in aviation, the ECHO project proposes a GNSS monitoring solution for airports, using a network of GNSS monitoring and interference detection stations at seven airports in Romania. This network of stations provides the user (ROMATSA) with periodic reports about GNSS performance and real-time alerts regarding the GNSS status and interference events. 

Each monitoring station has a GNSS Signal In Space monitoring component, containing a GNSS receiver and antenna, and a RF interference detection component, containing four antennas and interference monitoring receivers. The stations have been installed at seven airports, in Bucharest, Constanta, Craiova, Suceava, Bacau, Timisoara and Baia Mare, in locations free of masking obstacles. 

There are two information paths in the ECHO architecture. On the real-time path, the data coming from the stations is assessed by the real-time module, which determines the GNSS status and identifies the presence of interference. In case an event occurs (i.e. the GNSS status is degraded or an interference is detected), an alarm is sent to the user. The other path is for performance assessment. The data logged by the stations is used by the performance analysis module, for the computation of the GNSS performance parameters and their evaluation against the corresponding thresholds. The obtained results, along with interference statistics inputs, are transmitted to the reporting module, which provides 14-days reports to the user. 

Web interface showing the status at all stations in the ECHO network

ECHO is a project developed in the ESA NAVISP Element 3 programme, by a consortium containing RISE as prime contractor and the Romanian Space Agency and ROMATSA as subcontractors. The project started in 2021, having a planned duration of two years. To reach the final goal of deploying a pilot network of GNSS and interference monitoring stations, the activities in ECHO include the consolidation of system requirements, the survey of suitable locations for the stations and the installation of the equipment, the software development of the processing modules and a safety and security assessment of the impact of the detected events on airport operations. 

The GNSS monitoring system developed in the ECHO project is designed to be scalable and easy to maintain at all Romanian airports. This shall allow Romania to align with the international recommendations regarding the GNSS monitoring activities that support the adoption of Performance Based Navigation procedures.