The pros and cons of GNSS spoofing jamming

　　Jamming is less sophisticated and easier to do. It also works pretty well. Even low-powered jammers—of the kind often used by commercial drivers to stop their employer tracking their vehicle’s movements—are effective at drowning out GNSS signals to a range of several hundreds of metres.

　　And there lies one of the many problems with using GNSS jamming to defend against drones. Because they’re effective over a wide range, GPS jammers are illegal in most countries.

　　While the military-grade jammers likely to be used for drone defence are directional—effectively radio guns— they still have the potential to disrupt anything in their range. That creates significant risks for airport infrastructure that relies on GNSS, such as modern landing systems and air traffic control systems, as well as any other GNSS-dependent operations in the vicinity.

　　A lorry driver with GPS jammers caused “harmful interference” to a GPS-based landing system at Airport. That incident alone indicates that without a thorough risk assessment and risk mitigation effort, jamming GNSS at or near an airport could easily cause more problems than it solves.

　　The same caveats apply to GNSS spoofing. In theory, this can be an elegant method of taking control of a rogue drone. Todd Humphreys of the University of Texas at Austin was the first to demonstrate that a drone could be targeted with a false GPS signal , enabling the person operating the spoofer to force the drone to fly a different course from its intended one. It’s believed in some quarters to be the method used by Iran to capture a US military drone.