There are a number of technologies in development designed to thwart dangerous drones from entering no-fly zones or inflicting harm on civilians. Among them, radio frequency (RF) jamming, or jammers, can be used to disrupt the RF signal of the drone, causing it to fail.
A RF jammers is designed to disrupt a UAS or drone by blasting electromagnetic noise at RF, used by drones to operate and transmit video at, at a level high enough to disrupt any effective communication between the system and its pilot. Ref
Generally, this RF-Jamming is either at 2.4Ghz or 5.8Ghz, which are “non-assigned” public frequencies. Using these frequencies the jammers will not interfere with manned aircraft, mobile communication, public broadcasts, or other dedicated radio bands.
Jammers are effective against drones over several kilometres distance. The majority of RF jammers operate on a ratio of distance between a drone and the jammer compared to the drone with its pilot. Generally, The further away the drone is from the pilot and closer to the jammer, the better. A typical effective jammer direction is a cone of about 15-30 degrees, projecting forward from the gun (this is also influenced by the RF band and the power of the jammer).
In addition to RF-jamming, GPS jamming may also be utilised, as a large number of drones rely on GPS either to balance against wind, or to navigate between pre-determined points.
When a drone is intercepted by a RF jammer’s signal, the system usually returns back to its origin point (unless the GPS is also jammed), giving the user the possibility to track the drone back.
Alternatively, a jammed drone might even perform a vertical descent and land on the spot, providing the option of performing a forensic investigation.
The limitations of RF Jammers for countering rogue drones threats.
In recent test scenarios however, a number of analysts agree that signal jamming as a counter-measure often does more harm than good. For example, in December2019, an incident at Gatwick International airport in London saw two rogue drones flying within the airport’s restricted airspace. Gatwick officials reportedly attempted several methods of remediation including jamming the drone’s RF signals, which proved ineffective.
- Lack of precision
The level of precision required to accurately jam the drone signal without interfering with other signals that rely on the same radio band is technically difficult to achieve.
The person jamming the RF signal must point the jammer at the moving target and account for multiple variables — from speed and velocity to distance, direction, angle of arrival and altitude, while at the same time ensuring they are not pointing at or near any objects that could be negatively affected by jamming RF signals in the area.
Also, criminal or terrorist-operated drones can be intentionally flown on a GPS waypoint, thereby eliminating the RF signal entirely.
2. Risks of Collateral Damage
The operator needs to guess at the RD band on which the signal is running. The typical range from 2.4 to 5.0 Ghz means that any system operating within this range could also be also disrupted.
This can be potentially disastrous. For example, Air traffic controllers use radio to communicate between the pilot and the tower. A jammed signal could potentially disrupt this communication.
A disrupted signal could halt communication between these critical operations, resulting in air and ground traffic calamity. Airport commuters and guests using WiFi can also have their signal disrupted creating a huge inconvenience.