There are a number of technologies in development aimed at preventing dangerous drones from entering no-fly zones or harming civilians. Among them, radio frequency (RF) jamming, or signal jammers, can be used to destroy the RF signal of the drone, thus causing it to be disabled.
RF jammers are designed to interfere with UAS or drones by emitting RF electromagnetic noise, which drones use to operate and transmit video high enough to interrupt any effective communication between the system and its pilot. Refer to
Typically, this RF interference occurs at 2.4GHz or 5.8GHz, which are common "unassigned" frequencies. Using these frequencies, jammers do not interfere with manned aircraft, mobile communications, public broadcasting, or other dedicated radio bands.
Jammers are effective against drones from miles away. Most RF jammers operate based on the ratio of distance between the drone and the jammer and the drone and its pilot. In general, the farther away the drone is from the pilot and the closer it is to the jammer, the better. A typical effective direction for a jammer is a cone of about 15-30 degrees protruding forward from the machine gun (this is also affected by the RF band and the power of the jammer).
In addition to RF jamming, GPS jamming can also be used, as a large number of drones rely on GPS to balance themselves against wind or navigate between predetermined points.
When a drone is intercepted by a signal from an RF jammer, the system typically returns to its origin (unless the GPS is also interfered with), enabling the user to track the drone.
Alternatively, a stuck drone could even perform a vertical descent and land in place, providing an opportunity for forensic investigation.
The limitations of RF jammers in countering the threat of malicious drones.
However, in recent test scenarios, many analysts believe that signal jamming as a countermeasure often does more harm than good. For example, in December 2019, there was an incident at London's Gatwick International Airport in which two rogue drones flew through the airport's restricted airspace. Officials at Gatwick Airport reportedly tried several remedies, including jamming the drone's radio frequency signal, but all proved ineffective.
The level of accuracy required to accurately jam a drone signal without interfering with other signals that rely on the same radio band is technically difficult to achieve.
A person who interferes with an RF signal must point the jammer at a moving target and take into account several variables - from speed and velocity to range, direction, Angle of arrival, and height, while making sure it is not pointed at or near the object. This can be adversely affected by interfering RF signals in the area.
In addition, drones operated by criminals or terrorists could deliberately fly over GPS waypoints to completely eliminate RF signals.
The operator must guess the RD band in which the signal is running. The typical range of 2.4 to 5.0 Ghz means that any system operating in this range may also experience interference.
This could be disastrous. For example, air traffic controllers use radios to communicate between pilots and the tower. Scrambled signals may interrupt this communication.
Interrupted signals can interrupt communication between these critical operations, resulting in disaster for air and ground traffic. Airport commuters and customers using WiFi could also have their signals disrupted, causing huge inconvenience.
