If the buzz of an overhead drone still manages to startle you, get used to it! The use of drones has expanded across all walks of life (recreation, science, agriculture, journalism, medicine, military, logistics, etc.) and, inevitably, to the darker side as well. The versatility of drones has been discovered by criminal and terrorist organizations, who now regularly deploy them as a type of shoestring air-force for surveillance, delivery of illicit goods or in full-on attack mode. Individually or in swarms, rogue drones pose a threat that every law-enforcement, security consultant and defense agency must account for. One of the earliest counter-measures developed against drones has been RF jamming, which targets the communication channel between the drone and its operator. Fixed-area solutions, as well as mobile, hand-held transmitters, are readily available to protect valuable assets from the threat of unmanned aircraft that can cause a variety of damage. While this is a relatively low-cost solution, the sheer simplicity of it can limit its usefulness.
The Limitations of Jamming
Drones are small, a speck in the vast airspace surrounding any target, be it a person or an installation, stationary or mobile. In order, for example, to protect an airport from a drone threat by jamming its RF communication, it is necessary to detect the presence of a drone/s, identify the communication frequency and interfere with it at such a distance as to negate the threat. These variables render targeted jamming an unreliable solution, since it takes some time to lock in and analyze the signal and frequency switching is common. On the other hand, broad defense measures such as blanket interference can cause numerous unintended circumstances, since RF signaling has a very broad range of civilian uses (not the least of which is to air-traffic control).
In addition, because an RF signal can easily be disrupted by random interference, the drone industry is evolving to address this vulnerability by securing the communication channel (necessary for safeguarding even the most casual everyday operations, such as delivering a package to the right address). And alternative guidance methods, such as GPS targeting, create ‘dark’ drones, that can fulfill their mission independently of any further instruction/communication with the operator.
While RF jamming is certainly the most widespread method for interfering with and defending against rogue drones, it is clear that as the use of drones becomes more widespread and their technology more sophisticated, the counter-measures employed against them will need to keep pace.