The Impact and Sources of Radio Frequency Interference on GNSS Signals.

The utilization of the global navigation satellite systems (GNSS) services in both military and civilian applications as well as for scientific investigation has grown exponentially. However, the increasing reliance on GNSS applications has raised concerns about potential risks from intentional radio frequency interference (RFI) transmitters. RFI significantly affects GNSS's environmental monitoring capabilities by inflating the scintillation index and misleading the scientific community with scintillation indices not attributable to ionospheric dynamic events. Consequently, the existing climatological distribution of GNSS scintillations may require careful reevaluation, as it may not adequately filter out RFI induced scintillations. Thus, characterizing the global RFI occurrence regions and developing real‐time detection capabilities to mitigate its effects is critically important. Leveraging GNSS measurements from ground stations and six COSMIC‐2 satellite constellations, we have developed a technique to detect RFI events and identify RFI active regions. Additionally, for the first time, we have implemented techniques that differentiate RFI associated scintillations from scintillations caused by ionospheric turbulence. Plain Language Summary: The global navigation satellite systems (GNSS) signals, transmitted by different navigation satellite constellations, are utilized by both military and civilian users for positioning, navigation, and timing (PNT) purposes. The GNSS services are also critically important for a wide range of modern economies, such as for surveying, geodesy, infrastructure, and farming applications. However, the performance of such services can be impacted by unauthorized radio frequency interference (RFI) transmitters that emit artificial noise (jamming) or false/modified pseudorandom noise (PRN) codes to deceive a receiver into calculating a false position (spoofing). We developed a technique that allow us to identify RFI events from GNSS observations and to pinpoint distinct regions where RFI is more active and intense. We also demonstrate that RFI can induce scintillation—referred to as "fake scintillation"—which is distinct from the scintillation caused by ionospheric irregularities, potentially sending false alarm to users of scintillation all‐clear zone map. Our result clearly shows that RFI is often present in the vicinity of conflict zones and affect GNSS signals similarly to how signal blockage, foliage attenuation, ionospheric scintillation, and multipath do. Intentionally generated L‐band (GNSS frequency band) RFI transmitters can be ground‐based or space‐based (orbital transmitters) and are frequently deployed for military purposes by governments and independent groups to deny regional access to GNSS capabilities, and more recently, to prevent the use of unmanned aerial vehicles (drones). However, such unintended RFI transmitters have the potential to disrupt GNSS applications or halt service operations (navigation blackout), thereby endangering human safety by providing false information to the users. Key Points: Intentional radio frequency interference (RFI) affects global navigation satellite systems signalsRFI significantly inflate the scintillation index not attributable to ionospheric dynamic eventsRFI active zone correlate with regional conflicts and other geopolitical activity/events [ABSTRACT FROM AUTHOR]