Drones or unmanned aerial vehicles (UAV) have many valuable applications in various industries around the world. They can do things that once required costly equipment and were dangerous to carry out. From crop monitoring to reconnaissance missions, drones can accomplish most of the difficult tasks with ease. Although most drones are used for legitimate tasks, a small number of users use drone technology for illegal or criminal activities. Though the misuse happens on a tiny scale, the number of incidents is on the increase, with 3456 reports registered 2016 in the UK, which is a 352 percent increase from the previous year. This article looks at how one can detect and monitor against unauthorized drone use.
With modern drones equipped with state-of-the-art sensors and imaging devices, people can commit an endless range of criminal activities, including spying on individuals, properties, and security systems to spot weak points, smuggling contraband across borders and into prisons and corporate espionage by covertly monitoring employees or buildings. There were reports that criminal gangs use drones even to intimidate.
Besides illegal use, there is also a risk of careless and dangerous drone flying, pausing a potential threat to people and aircraft in case of an accident. To prevent reckless or criminal drone flying, the UK government has introduced new legislation in 2018, placing restrictions on flying drones above 400ft and within 1km of an airport. It also mandates the drone pilots to pass an online safety test. The penalty for violation of law includes unlimited fines and prison for up to five years.
How to detect and monitor unauthorized drones?
Legislations can not wholly prevent determined criminals from using drones to compromise security systems. We must take adequate measures to limit the potential risks with the use of an effective drone detection system. A drone mitigation system (counter-drone system) uses a multilayered approach, consisting of a network of video cameras, infrared and RF sensors integrated with analytics software to detect and control trespassing drones. The data can then be linked with an onsite law enforcement team to provide further protection.
One such drone mitigation system is DJI AeroScope, a comprehensive platform that can quickly identify and gather information such as flight status and paths in real-time to help users make an informed response as soon as possible.
Deployed as a fixed or portable solution, AeroScope can detect trespassing drones in extreme and most hostile environments. It tracks the drone signals to identify the location of the pilot, drone serial numbers and current airspeed, allowing the security personnel to attend and warn the pilot on the restricted drone usage in the area. The fixed unit has a larger antenna, covering an area of 25 square miles and allowing security teams to cover an entire site such as an airport, prison or an open-air stadium. It uses several large aerials located around the site, connecting to a central monitoring station. The portable unit can cover 10 square miles, depending on the terrain. A fixed unit is most suitable for large facilities, while the mobile unit is best suited for smaller sites and one-off events.
Some of the other counter-drone technologies include DroneGun, DroneCatcher, SkyWall 100, SkyDroner, and Sky Fence System. Some of these systems rely on a variety of techniques for detecting or intercepting drones, such as;
- Radar-based systems detect drones by their radar signature, generated when they encounter RF pulses. They employ algorithms to distinguish between drones and birds.
- Radio-frequency (RF) identifies drones by scanning the frequencies on which most drones operate. Algorithms geo-locate RF-emitting devices that are likely to be drones.
- Electro-Optical (EO) uses visual signature to detect drones.
- Infrared (IR) uses a heat signature to detect drones.
- Acoustic recognizes the unique sounds produced by their motors and relies on a library of sounds produced by known drones.
- RF Jamming is a technique to disrupt the radio frequency link between the drone and operator by generating large volumes of RF output. Once the RF link, a drone will either descend or activate the “return to home” mode.
- GNSS Jamming disrupts the satellite links, such as GPS or GLONASS, used for navigation. Once the satellite link is lost, the drones will land, or return to home.
- Spoofing takes control of a drone by hijacking its communications link.
- Laser destroys the drone’s airframe using directed energy, causing it to crash to the ground.
- Nets are designed to entangle a targeted drone or its rotors.
- Projectile uses ammunition to destroy incoming unmanned aircraft.
Counter-drone systems are not without challenges. Every detection system has drawbacks. Since drones are small and tend to fly at low altitudes, they can be difficult to detect by radar. The electro-optical systems can only operate during daytime and can confuse a drone with a bird. EO and IR systems need a direct line of sight with the intruding drone. The acoustic sensors rely on a library of sounds by known drones, and they might not identify drones not covered by the library. RF detection systems detect certain frequencies in a library that needs to be regularly updated. They may also be less effective if a drone is not operating within a direct line of sight of the sensor.