  Global Navigation Satellite System (GNSS) receivers provide ubiquitous and
precise position, navigation, and time (PNT) to a wide gamut of civilian and
tactical infrastructures and devices. Due to the low GNSS received signal
power, even low-power radiofrequency interference (RFI) sources are a serious
threat to the GNSS integrity and availability. Nonetheless, RFI source
localization is paramount yet hard, especially over large areas. Methods based
on multi-rotor unmanned aerial vehicles (UAV) exist but are often limited by
hovering time, and require specific antenna and detectors. In comparison,
fixed-wing planes allow longer missions but are more complex to operate and
deploy. A vertical take-off and landing (VTOL) UAV combines the positive
aspects of both platforms: high maneuverability, and long mission time and,
jointly with highly integrated control systems, simple operation and
deployment. Building upon the flexibility allowed by such a platform, we
propose a method that combines advanced flight dynamics with high-performance
consumer receivers to detect interference over large areas, with minimal
interaction with the operator. The proposed system can detect multiple
interference sources and map their area of influence, gaining situational
awareness of poor GNSS quality or denied environments. Furthermore, it can
estimate the relative heading and position of the interference source within
tens of meters. The proposed method is validated with real-life measurements,
successfully mapping two interference-affected areas and exposing radio
equipment causing involuntary in-band interference.
