Having created a bow wave of enthusiasm and a new industry around Unmanned Aerial Vehicles (UAVs) of all sizes, there is now a pressing need by governments and the military to be able to bring them down, or at the very least prevent them from reaching an intended target.
In late October 2014, strange Unidentified Flying Objects (UFOs) were reported hovering over several nuclear power stations in France. Conspiracy theorists rushed to tell the world that the UFOs were visitors from another world, performing an initial reconnaissance for a massed, alien invasion of Earth. Why these visitors were so interested in nuclear power stations was not explained by the theorists, who instead urged vigilance in case our extraterrestrial visitors had now taken human form and were living amongst us.
The truth of the incident was far more prosaic, but a cause for concern. Between that month, and the end of November 2014, consumer-purchased UAVs, known as ‘drones’ in the commercial world, had been flown over 13 of the 19 nuclear power plants operational in France by environmental protestors to highlight the lack of security against air attack at these facilities. Defending such installations against attack from the air is a major concern. In the wake of the 11 September 2001 Al Qaeda attacks on New York and Washington DC, France rushed to implement air defences around its nuclear power stations, which generate 75 percent of the country’s electricity, according to March 2016 figures published by the World Nuclear Association, an industry group. Across the channel, the response of the United Kingdom to the perceived threat was to deploy ‘extra police’.
The incident discussed above raises some serious issues. That environmental protestors were able to fly their aircraft over and above the nuclear power stations undetected and unchallenged, illustrated that those with more nefarious intentions maybe able to do the same thing, potentially mounting explosives on the UAV and crashing it into the reactor hall or another part of the complex, which could lead to the dispersal of radioactive material. Small UAVs could also be used to target important individuals. This was nowhere better illustrated than when a Parrot AR UAV hovered then landed in front of the German Chancellor Angela Merkel and defence minister Thomas de Maiziere during a rally in the eastern German city of Dresden on 15 September 2013. While it was almost treated as an annoying distraction at the time, security specialists are alarmed at the very real threat today that something similar could carry a remote-controlled bomb onboard to be detonated in close proximity to the target.
Away from the homeland security situation, troops on the battlefield also face the threat of UAV attack. Small, commercially-available drones, which can be purchased for a few hundred dollars, but mounted with explosives, could be used by insurgents to target squads of soldiers, individual vehicles, or even command centres making them a potentially devastating asymmetric weapon. Similarly, these drones could be outfitted to carry chemical, biological or radiological agents to attack either troops, or civilian targets. To make matters worse, such flying machines are often small in physical size making them a challenge to detect by radar, and to then engage using surface-to-air missiles, or anti-aircraft artillery. Clearly then, there is a growing need to protect people and installations from these smaller, sometimes individually-controlled, UAVs.
A company usually reputed for its expertise in UAVs, Northrop Grumman, has developed its own counter-UAV system called Venom. Demonstrated at the Army Maneuver-Fires Integrated Experiment (MFIX) held at Fort Sill, Oklahoma, on 8 December, 2015, the Venom confirmed its ability to identify and track small UAVs, even when mobile. The Venom combines a Lightweight Laser Designator Rangefinder (LLDR) on a universal, stabilised and gimballed mount. The system receives slew-to-cue messages which allow it to identify, hold and track low-flying, small UAVs. The US Army’s interest in anti-UAV technologies has increased significantly in recent years. For example, in July and August 2015, the US Department of Defence (DoD) held Exercise BLACK DART at Point Mugu, California, where the US Navy, US Army, US Air Force and US Marine Corps all sent representatives, along with several allied nations, and personnel from industry, to test and evaluate technologies which could be employed for the anti-UAV mission.
The DoD has in fact been performing the BLACK DART exercises since 2002, although these initiatives, as the exercise name suggests, have been in the ‘black’ until the DoD revealed their existence in 2014. In 2014, Exercise BLACK DART included live fire trials against UAVs over a variety of environments including land, the littoral and the open ocean. The exercise also focused closely on detecting and intercepting small UAVs. This has gained added interest in the US and beyond when, in an incident closely mimicking that involving Dr. Merkel discussed above, a civilian Quadcopter UAV crashed into the South Grounds of the White House in Washington DC in January 2015, sparking the lockdown of the commander-in-chief’s residence and prompting questions within the Secret Service, which guards the US President, and the wider defence and security community, how such incidents can be prevented in the future. The use of UAVs for criminal or violent activity clearly is also a concern for law enforcement officials as much as it is for soldiers. This means that the solutions which are developed to protect against such threats must not only able to perform their role, but must be affordable for police departments which may not have similar budgets to their military counterparts.
Away from the United States, the incidents in France and Germany discussed above have prompted significant interest in Europe’s defence and security establishment regarding the small UAV threat. During the Defence Security Equipment International exhibition in London 2015 there were a number of counter-UAV systems launched including the Falcon Shield from Finmeccanica’s Selex ES division. It is a modular and scalable system that combines a radar with an optronics system to “find, fix, track, identify and defeat” the perceived threat, according to the company.
The Falcon Shield adopts an interesting approach. It employs both optronics and an Electronic Support Measure (ESM). The optronics and ESM combine their talents to detect the UAV, with the optronics performing a visual detection, and the ESM listening for the Radio Frequency (RF) transmissions that the UAV requires to fly. For example, in the US, the Federal Communications Commission, which manages the electromagnetic spectrum, allocates 27 to 49 Megahertz (MHz) within the high end of the High Frequency (3-30MHz) and the low end of the Very High Frequency (VHF) radio spectrum of 30-300MHz to be used for civilian radio-controlled models. Thus the ESM will be able to detect the UAV’s RF emissions and then geo-locate the aircraft, aided by the optronics and also a radar organic to the Falcon Shield. According to Finmeccanica the Falcon Shield will then ‘electronically attack’ the UAV’s RF command link to decouple it from its source and land it, rather than completely breaking the link and have the aircraft fall out of the sky onto a random location.
This takes care of two aspects of air defence against UAVs, firstly employing the RF link between the aircraft and its controller as the ‘Achilles Heal’ by which the interdiction of the aircraft can take place. Secondly, by taking control of the UAV and landing it safely, this avoids the hazard of the aircraft simply falling out of the sky and posing a danger to those on the ground. Such attributes could be of particular interest to law enforcement organizations that may have to tackle illegal drone use in built-up areas, where the use of kinetic weaponry may also be impossible and also too expensive. According to Steve Williams, the capability manager for Falcon Shield, the range of interception will reduce correspondingly with a reduction in size of any potential UAV threat.
In May 2015, three British companies announced their own collaborative Anti-UAV Defence System (AUDS). They comprised Blighter Surveillance Systems (a manufacturer of ground surveillance radars), Chess Dynamics (a producer of optronic surveillance systems) and Enterprise Control Systems (ECS), a specialist in jamming technology. The fruits of their labour have produced a counter UAV system that uses radar for detection, optronics for tracking and a directional RF jammer which disrupts the UAV’s flight. The AUDS can scan in a 180 degree arc. Once identifying a potential threat, its jamming capability will break the RF control channel between the operator and the UAV, allowing it to be brought down under control. Initial test results showed that micro-UAVs could be detected at around one nautical mile/nm (two kilometres/km), while mini-UAVs could be seen as far away as 4.3nm (eight kilometres). Although it can only disrupt one UAV at a time, the AUDS can keep tracking several simultaneously. Graham Beall, managing director of Chess Dynamics, told Armada, “You could run the whole thing off a 13amp plug.”
Elsewhere in Europe, Airbus’ defence and space division has developed its own anti-UAV system known as the C-UAV which combines sensor data with data fusion, signal analysis and jamming. According to Airbus, the system uses “operational radars, infrared cameras and direction finders from the (company’s) portfolio to identify the (UAV) and assess its threat potential at ranges between 2.6-5.3nm (five to ten kilometres).” The direction finder will also reveal the location of the operator, a useful bonus for the authorities. The system is expected to be operational from mid-2016.
Drone Guard, a system from Israel Aerospace Industries’ (IAI) subsidiary ELTA, was also revealed in 2015. This uses a combination of three-dimensional (3D) radars and optronics to detect and identify a target, then an Electronic Attack (EA) jamming systems to prevent the UAV from continuing on its course. The jamming interferes with the flight of the UAV to the point where it either automatically returns to its point of origin or crashes. IAI uses 3D radars such as the EL/M-2026D, EL/M-2026B and EL/M-2026BF for short (5.3nm/ten kilometres), medium (eight nautical miles/15km) and long (10.7nm/20km) range detection. The company confirms that the Drone Guard has been “extensively and successfully tested against a variety of different drones and scenarios, including simultaneous multiple drone penetrations or attacks.” According to Nissim Hadas, IAI executive vice president and ELTA president, demonstrations to potential customers are already being conducted.
Staying in Israel, Rada Electronic Industries, whose MHR Very Short Range Air Defence radar has been ordered by the Israeli Ministry of Defence (MoD) to guard the country’s southern border, is another Israeli product capable of detecting UAVs. The MHR S-Band (2.3-2.5/2.7-3.7GHz) family comprise Pulse-Doppler, active electronically scanned array radars which employ sophisticated beam-forming capabilities and advanced signal processing. The manufacturer states that the system can detect “from significant ranges …commercial Low, Slow and Small aerial vehicles such as quadcopters.”
Israel is no stranger to the UAV threat. Although the country is a centre of excellence for UAV design and production, and its armed forces an avid user of such platforms, it increasingly faces a threat from such aircraft by non-state actors. In 2012 and 2013, small UAVs were flown from Lebanon into Israel to gather Imagery Intelligence (IMINT), and on both occasions, these were shot down by Israeli Air Force fighters. Speaking in 2012, Hassan Nasrallah, the secretary general of the Hezbollah Palestinian insurgent organization, stated that Hezbollah had flown a UAV 21.5nm (40km) into Israeli airspace. While these previous sorties have employed small UAVs, allegedly supplied by Iran, to gather IMINT, the understandable fear of the Israeli defence establishment is that such aircraft may be used in the future to carry explosives, or worse. Little surprise then that other Israeli companies are involved in developing anti-UAV systems. For example, Controp has devised the Tornado optronics-based air surveillance system which provides a 360-degree panoramic image every two seconds and can operate in a stand-alone mode or integrated with other defensive systems. Controp states that it can detect anything from conventional aircraft to small UAVs.
As successive US-led military operations in Afghanistan, the Balkans and Iraq have illustrated over the past two decades, UAVs are a feature of modern warfare and are here to stay, with their employment expected to only increase in the future. However, recent events in France, Germany, Israel and the United States underline the dangers posed by UAVs falling into the hands of criminal or guerilla elements, in addition to the threat they pose to soldiers on the battlefield as an asymmetric weapon. Yet the minds of defence science and technology engineers are already turning their attentions to this threat, and devising innovative solutions.