| Abstract | Remotely Piloted Aircraft Systems (RPAS), or drones, can carry out a variety of missions in urban environments, including traffic monitoring, civil infrastructure inspection and photography. However, drone pilots can face multiple command and control challenges during urban operations. Dense urban areas, where streets are flanked by high buildings on both sides, can create urban canyons.
In this environment, signal propagation can be blocked or received through multiple paths by reflection, refraction or scattering off building surfaces, which diminishes signal quality. Drones rely on the Global Navigation Satellite System (GNSS) for navigation requiring an unobstructed line of sight to the satellites. Buildings can reduce the quantity of satellites visible to the drone and impair the drone’s flight control system. Probability models of signal line of sight are presented, along with simulations to understand the influence of certain parameters such as flight altitude, width between buildings, and the Fresnel zone on the probability of reception. The influence of other physical factors such as weather conditions and antenna positioning is also discussed.
Electromagnetic interference (EMI) can affect a drone’s navigation system and command and control (C2) link. Both natural sources and artificial sources can cause EMI. The main EMI sources in urban areas are presented and types of soft failure are classified according to their level of impact. The distinction between front-door EMI and back-door EMI (based on the route through which it enters the circuits of RPAS electronics) is discussed. |
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