Combating the threat of unauthorized drones and UAS
Commercial drones have many positive and legitimate uses, but there are increasing concerns that drones are being used for illegal and dangerous activities. Flying too close to passenger aircraft, smuggling drugs and weapons into prisons, privacy concerns, weaponized drones. The list is growing daily as are the incidents.
To combat the threat of drones CRFS advocates a multi-sensor approach combining its RF Drone Detection system with other sensors such as radar, infra-red, acoustic and optical amongst others.
How RF spectrum monitoring can help
Commercial drones are usually operated via a radio control signal and often have on-board data link transmitters for real-time sensor download (typically in the 2.4 GHz ISM band). These can be detected and geolocated with a network of RFeye Nodes well before the drone enters a protected area such as an airport, a prison or a government facility. In addition, the system can detect the location of not only the drone itself, but also of the source of the control signal – i.e. those responsible for any crime or nuisance behavior. Countermeasures such as signal jamming or firing nets may then be used to neutralize the threat.
How it works
The system is based around a network of RFeye nodes that are set up around the facility that is to be protected. These intelligent nodes passively detect and identify the presence of RF transmissions that relate to drones, even if the signals are of low power or in RF noisy conditions. The transmissions can be geolocated in 3D to give the location of the drone, its flight height and air speed. Multiple drones can be simultaneously tracked and identified. If a drone is detected, the system triggers an alert that can then be verified by the other sensors deployed.
How drones can avoid detection
By relying on just one detection method it can be possible for a drone to be missed. For example, when using conventional radar, it can be difficult to detect low-flying drones or distinguish drones from birds. Or if the drone is obscured by buildings or trees, an optical sensor will struggle to pick it up. By augmenting the radar and optical sensors with spectrum monitoring, the security team have a much clearer picture of any potential drone activity.
However, spectrum monitoring isn’t the answer in all scenarios. RF detection will only work when there are RF signals present. There are drones that can operate without any radio control signal and can fly using pre-programmed GPS waypoints. In these scenarios it is essential to have a comprehensive suite of sensors working together to maximize detection probability, minimize false alarms and optimize geolocation uncertainty.