How Governments can counter the threat of drones


Stephen Harman, QinetiQ Fellow in Radar and Electronic Warfare

Unmanned aerial vehicles (UAVs) or drones offer tremendous opportunities for good: they can be used for filming, delivering commercial products or delivering humanitarian aid to some of the most dangerous locations on the planet.

Obsidian Counterdrone Graphic depicting a drone or UAV flying outside of an exclusion zone dome in a 3D cityscape

Increasingly, however, drones are being used in uglier, more threatening ways: either to invade privacy by watching or listening in on individuals – ranging from politicians and VVIPs to well-known actors on film or tv sets - or to deliver threatening payloads, as happened in Iraq, Syria and most recently, if media reports are to be believed, in Venezuela where an attempt was made on the life of President Nicolas Maduro.

Use of UAVs for surveillance and threatening behaviour by adversaries is unfortunately becoming ever more common. The challenge for Governments and organisations involved in the protection of critical national infrastructure and public safety during major events, is how to counter this low cost technology which is evolving and adapting rapidly.

What is the nature of the threat from drones and what detection and defeat solutions can QinetiQ offer?

How can drones be detected and tracked?

Drones are challenging targets to detect because they are small, can fly slowly and hover, are agile and low flying, and can easily be confused with other targets such as birds or people walking on the ground, or can be fleeting to keep track of, flying between buildings or trees.

Of critical importance in any solution is reliably identifying and recognising a drone target. To detect them, many companies use radio frequency (RF) sensing and direction finding (DF) devices. These alone are far from reliable given how busy the modern wireless signals environment is and because drones can be autonomously flown between GPS way points or without GPS. Drone communications will also be increasingly difficult to detect in the future as they use more complex signals. Similarly, acoustic and imagery sensors are not sufficiently capable to act as a primary drone sensor.

We have therefore concentrated on 3D radar as a primary sensor – drones can do little to hide their physical presence, which makes radar the most reliable sensing technology.

At what range can drones be detected?

It’s important to differentiate between large ‘military’ fixed wing platforms, which can have a range of 15-20km, and are most suitably detected by conventional air traffic control radar, tracking systems or very large distributed sensors, and small ‘civilian’ drones, which can be bought on the internet or the high street. These are likely to be flown at a range of 1-2km away from a target, as in the recent BBC News reports highlighting cases of drones delivering contraband into prisons. 

However, it’s not all about range. Our customers tell us that drones are taking off a few kilometres away and are flying at height in an attempt to avoid detection systems. What this all means is that we have to take a 3D approach to drone detection – looking in all directions not just sideways. While it’s informative to know what’s flying at range, it’s most critical that around the high value asset which you are trying to protect, whether that is people, buildings or critical national infrastructure you define a 3D space – think of it as an invisible ‘dome’ - within which you intend to act, and ensure that your detection and defeat performance in this area is robust. This ‘dome’ is of the order of 1-2km, outside of which alarms are more likely to cause nuisance than to be of significant operational value.

Again, 3D radar performs this task well, and has been shown to provide the necessary performance and reliability of both detection and drone classification.

Once detected, what do customers want to know about the drones?

The counter-drone market is extremely diverse. Many of our customers simply want to know that a drone is present so that they can act: for example moving the high value asset or individual. At the other extreme, some customers want to know what type of drone is being flown, where the pilot is situated, and whether the drone has a dangerous payload.

If you’re able to track drones accurately, as with radar detection systems, the track points to where the drone took off from, and where it landed, so you’re able to see where the pilot is operating from. Camera systems may also augment the radar detection system, and, depending on range, show whether the drone is carrying a payload. Flight characteristics may also show how heavily a drone is laden, through the loading of the motors.

Our Obsidian Counter-UAV system uses a combination of our 3D radar, and commercially available camera systems to provide robust 3D detection and secondary ID through imagery and video analysis. Our open architecture also means we can rapidly and cost-effectively integrate additional third party sensors as necessary.

How can drones be countered?

At present there are significant regulatory issues surrounding drone defeat, and Governments are grappling with how to legislate around defeat systems which could harm people nearby or cause collateral damage to surrounding buildings. There is encouraging progress on this in the UK. Legislative issues aside however, defeat options broadly fall into two categories:

  1. Radio Frequency effects
    These range from simple ‘barrage jamming’ - transmitting noise on frequencies that drones use for communications and video transmission to generate RF interference, through ‘RF spoofing’ – mimicking the drone control signals to ‘take over’ the drone and re-direct it, to ‘High Power RF’ techniques, which can disrupt the electronic circuits within the drone and cause a range of effects, from deterrent to disruption to denial to hard stop. We have specific capability in this area and has proven the ability to induce a range of responses in drones: from disrupting the camera of a hobbyist to deter them, to disabling the drone propeller motor controllers to bring it rapidly to ground  - as may be necessary to protect high value assets or VIPs.
  2. Kinetic effects
    Typical kinetic effects range from ‘nets’ – either manually fired at a drone or mounted on turrets surrounding a high value asset and utilising parachutes to bring the drone to the ground safely, through ‘darts’ – lightweight projectiles which disable the drone, to good old fashioned ‘rifle rounds’, which have been used by the military in more remote locations but are hardly suitable for used in crowded urban areas!
QinetiQ’s solution: Obsidian Counter-UAV System

Ultimately, the only viable approach to countering drones is a layered approach, taking different defeat technologies and rapidly integrating them into a solution which meets both specific customer requirements and legal constraints. The primary sensor is again of critical importance, as accurate and timely drone location updates are essential to reliable drone defeat.

We have developed our Obsidian Counter-UAV System with the above in mind. Obsidian is designed around a purpose-built 3D staring radar which calculates reliable and rapid drone position updates.  From these updates, which are provided many times a second, we are able automatically and accurately to set-on cameras and defeat options as appropriate.

As well as developing our own high power RF defeat capabilities which will come to market in the next 12-18 months, we are working with a number of suppliers of RF and Kinetic drone defeat systems which may be offered immediately.

All this presents an exciting and dynamic engineering challenge for our teams, and encompasses a wide range of technical and systems engineering disciplines from the physics of flight, electronic systems design, RF transmission and reception and imagery analysis. The breadth of our legacy of world-class R&D positions us well to provide robust and capable systems to our global customers.

For more information about how QinetiQ’s Obsidian Counter-UAV System could protect your organisation’s people or assets please email us.