What are surveillance drones?
Surveillance drones are unmanned aircraft used to gather still images, video recordings or live video of targets such as people, vehicles or specific areas. They may be used by governments, militaries, law enforcement or commercial entities to gather information and intelligence that can be used to assist decision-making.
Using drones for surveillance can provide access to areas that may be difficult or impossible to reach by humans on foot or in land vehicles. Many drones are quieter than manned aircraft, can fly at lower altitudes and are less expensive to operate. Using military and law enforcement surveillance drones in potentially dangerous environments such as battlefields or crime scenes can also prevent putting humans at risk.
Types of surveillance drone
Both fixed-wing and multi-rotor drones may be used for surveillance. Fixed-wing UAVs are typically used to patrol larger areas such as coastlines, borders and long sections of road and infrastructure, as they have greater flight endurance and can cover a greater distance without recharging or refuelling. Multirotor drones are used for smaller areas as they have the ability to hover in place and are generally more manoeuvrable.
Drone tether systems can also be used to provide a quadcopter or multirotor drone with persistent surveillance capabilities. The UAV hovers in place while attached to a source of power on the ground via a tethering cable, which also transfers images and video to operators on the ground.
The U.S. Department of Defense classifies its unmanned aerial vehicles, which include various models of military and government surveillance drone, according to a group system that groups by factors such as maximum altitude. This system ranges from Group 1 (<1200 ft AGL) to Group 5 (> 18,000 ft).
Drone surveillance payloads
Drones equipped with specialised surveillance payloads can make a good alternative to satellites, which are expensive to operate and may not always be overhead at the required time. A range of payloads are available to suit different surveillance needs, such as military battlefield ISR (intelligence, surveillance and reconnaissance), border patrol and force protection.
Optical camera payloads provide full colour images and video, often in high-definition. Thermal cameras are used for night-time surveillance, detecting infrared (IR) radiation emitted by objects and assigning colours to different levels of radiation to build up a “false colour” image. Both optical and IR cameras may be combined into the same payload to allow drone surveillance to take place during the day and at night.