Detection of GNSS interference through natural hazard monitoring systems and next steps towards the development of an interference early warning system

The ability of GNSS to offer Positioning, Navigation and Timing (PNT) functions to existing and emerging applications and technologies is expected to drive significant advancement in multiple fields. Strategic Earth Observation infrastructure units, such as permanent GNSS station networks are increasingly integrated into civil protection strategies and operation plans, serving as decisive tools for monitoring the evolution of geohazards, and assessing their potential impact on the anthropogenic and physical environment. Nevertheless, GNSS performance is still vulnerable to unintentional or intentional interference, with the latter on the rise. Consequently, Interference Monitoring Networks have been developed worldwide to detect interference and pinpoint its sources by means of localization techniques, thereby enabling early warning and immediate resolution of interference problems. The severe effects of interference on the GNSS signal integrity have prompted significant research endeavours towards the development of efficient methodologies for the timely detection of interference sources. Specifically, in Cyprus and the Eastern Mediterranean region, existing infrastructure for monitoring natural hazards is readily available and in use for a significant number of positioning or geophysical applications. In Cyprus, the largest GNSS strategic infrastructure unit, CyCLOPS, has been operational since 2021, featuring state-of-the-art Tier-1/2 GNSS permanent stations, and calibrationgrade SAR corner reflectors installed throughout the country to monitor accurately active and ongoing geohazard incidents. Through this infrastructure, intentional interference events were recorded and analysed for the first time. This study reviews the ability of CyCLOPS to be utilized as an Interference Early Detection System by applying detection and analysis techniques. These techniques will be chosen appropriately taking into consideration existing equipment apparatus, topology and characteristics of the existing geohazard and similar monitoring stations. By incorporating additional equipment, the objective is to develop the first Cyprus GNSS Interference Early Warning System based on CyCLOPS, which will enable continuous monitoring of the GNSS signals for interference detection and localization.