By Megan Crouse
Technology to counter unmanned aircraft continues to develop. 2022 has seen two major areas of change: practical, battlefield use in Ukraine, and a U.S. Federal Aviation Administration (FAA) effort to test counter-unmanned-aircraft systems in commercial airports.
Military and commercial counter-unmanned-aerial-systems (UAS) are seeing wide deployment and experimentation. On the military side, adversaries may launch drones for reconnaissance, or arm them. In the commercial world, drones can be for photography to monitor large farms, or to deliver goods.
They also may have uses in an otherwise commercial setting, such as drug trafficking or smuggling. Ever since small drones became feasible to use, the question has been raised of how to deter them from, intentionally or by accident, causing damage to infrastructure and other vehicles sharing their air space.
A Counter-UAS system needs to function in three stages: detection, tracking and jamming, and capture or destruction. Each C-UAS system may feature one or more of these stages. Perimeter security for airports may see heavy air traffic and include a wide array of infrastructure and facilities.
The U.S. Department of Defense (DOD) has considered unmanned systems to be a threat sufficient to deploy technologies against them since at least 2014. The U.S. Government Accountability Office (GAO) notes that, although the counter-UAS field has matured since then, it still specializes in a relatively narrow window of drones against which it can defend. Small UAS that weight less than 55 pounds are more likely to get through a defensive screen; few technologies today can successfully jam the radio frequency (RF) control signals of a drone. While the effectiveness of modern jamming also ends at around 1,000 feet away at most many companies today are working on pushing the envelope.
Lessons learned the Ukraine war
The war in Ukraine has provided a real-world testing ground for UAS and counter-UAS systems. The inclusion of the VAMPIRE Counter-Unmanned Aerial System from L3Harris Technologies Corp. in a nearly $3 billion military assistance package from the U.S. made headlines in August. Although initially reported to be a counter-drone system, in fact, it’s a small missile that not only can launch against drones, but also against ground installations and low-flying piloted aircraft. That said, the Russian military is known to use drones in Ukraine for artillery spotting, general surveillance, and as improvised munitions.
Russia’s strategy of deploy a network of meshed low-cost sensors of different types to provide early identification of targets has shown mixed effectiveness against Ukraine’s small, mobile drones, experts say.
Energy infrastructure also may be a place where perimeter security designers should take drones into consideration. In July 2020, an unknown operator flew a drone near a power substation in Pennsylvania. Federal law enforcement indicated the drone was likely intended to cause a short circuit to damage transformers or distribution lines.
In June 2022, a drone flying too close to a runway at Reagan National Airport in Washington caused a 45-minute shutdown of air traffic because of safety concerns. Perhaps the most famous instance showing the importance of preventing drones from interfering with commercial airspace was the case of Gatwick Airport near London. In 2018, thousands of flights were affected by a sighting of a drone near the runway. A lack of effective detection and tracking contributed to confusion surrounding the event.
The U.S. Transportation Security Administration (TSA) and Federal Aviation Administration are working on testing practical applications for drone defense in several commercial airports. The TSA is testing C-UAS systems at two operating commercial airports as of August 2022, at Los Angeles International Airport and Miami International Airport. These airports were chosen because they are busy and see a high frequency of UAS activity already.
“While there are many beneficial uses for drones in our society, it is becoming far too common that drones are sighted near airports, which presents significant security risks and unnecessary disruptions to the traveling public,” says U.S. Rep. Lucille Roybal-Allard, D-Calif.
This is in addition to five other commercial airports chosen in March 2021 as hosts for the Airport Unmanned Aircraft Systems Detection and Mitigation Research Program, which will serve as a test bed for UAS detection and mitigation technologies for the FAA through 2023. The projects includes at least ten technologies or systems drawn from manufacturers, vendors, and integrators in 2020.
Another challenge to keep in mind in regards to C-UAS in perimeter security is the density of radio signals. C-UAS systems studied in 2017 did not have frequency accuracy, a 2022 Office of Inspector General report noted. This influenced what the FAA would communicate to vendors over the next few years, seeking better RF accuracy and cutting out the need for human operators to weed out false positives. Its guidance lead directly to the 2021 research program.
To some extent, the FAA is expecting delays on the program. They expect to be able to assess safety risks and benefits by 2024 at earliest, with leeway for the nation’s supply chain issues and other COVID-19 related barriers.
The TSA’s detect, track and identify (DTI) system at Los Angeles Airport demonstrates the capabilities such a system typically has. It operates 24/7 using RF waves, electro-optical, radar, acoustic, and thermal imaging. Using the Android Tactical Assault Kit platform, airport police can view a drone which approaches or passes the airport perimeter and tell its elevation, direction and type.
The FAA predicts that airports must contend with only more drones in the future. The commercial UAS fleet will reach around 828,000 by 2024, FAA experts predict, with another 1.48 million drones in the sky for recreational use. The commercial UAS traffic management market will be worth $1.9 million over the next five years, of which $720 million will come from government investment in research and early deployment, surveys show.
Several factors have slowed deployment of drone traffic management technologies, experts say, including budgetary constraints following the Covid pandemic, a lack of clarity in proposed regulations, and continuing confusion around the business case for UAS traffic management technology suppliers and service providers.
One company working on perimeter security for airports is DroneShield, of Warrenton, Va. The company's DroneSentry for civilian airports features passive long-range drone detection sensors and proprietary command-and-control software to detect drones in real time.
DroneShield also has a product notable for its small size: the military-grade DroneGun MkIII. Recently picked up by an undisclosed U.S. government agency, this is a pistol-sized passive UAS detection device which works by jamming drone RF control signals.
Other companies such as Flex Force Enterprises in Portland, Ore., also have been brought in by the Pentagon as approved distributors of handheld counter-UAS. Their Dronebuster, an RF jammer, can break the connection between a drone and its operator, and force it to return to base. The system also can overwhelm a drone’s satellite navigation signals to drive it home or render it inert.
Detection, interception, and neutralization
Enabling technologies for counter-UAS systems must combine detection, interception, capture, or destruction. Most C-UAS technologies use RF and radar systems to detect UAS activity in the surrounding area. Long-range radar can scan an area three or four times each second. According to the GAO's 2022 tech spotlight, other common methods include infrared devices, RF systems, and acoustic sensors. Respectively, these scan for heat signatures, RF control signals, and the sound of a motor. UAS detection and tracking from the ground often uses the same types of solutions used on the drones themselves, which typically are sound and radio, but can be much larger.
ASIS International, a security firm in Alexandria, Va., points out that the leading C-UAS approach is to layer multiple sensors. RF sensors might be combined with 360-degree, long-range radar. A benefit of these radars is their ability to detect small intruders like mylar balloons or parachutes.
From there, mitigation aims to prevent the drone from completing its mission or continuing through the airspace. According to a 2019 report cited by the GAO, jamming with interference signals is the most common method of mitigation. The people defending the airport or base perimeter also may use physical methods to bring the drone down, such as nets, lasers, or projectile weapons. The latter is particularly dangerous, though, because the drone or the shot itself may damage the very infrastructure one is trying to protect.
Last year, Aurora Flight Sciences, a Boeing UAS company in Manassas, Va., demonstrated a kinetic solution that fires copper discs attached to an air gun with string, intended to tangle in rotor blades.
Teledyne FLIR in Wilsonville, Ore., and InVeo Designs LLC in Louisville, Ky. benchmark potential C-UAS cameras with a new product, the Neutrino SX12 ISR1200 high-performance medium-wave infrared (MWIR). Capable of integrating with perimeter surveillance software, it features the Teledyne FLIR MWIR camera module and imaging electronics focusing on intelligence, surveillance, and reconnaissance (ISR) applications with low-switching-cost. Dual-parallel outputs use a 60 Hz Camera Link base with 1080P30 HD-SDI or 720P60 HD-SDI for tracking, turbulence mitigation, and artificial intelligence (AI).
Interception
After the detection stage, it’s time to get the unwanted drone out of the protected airspace or stop it from operating. Using video analytics and RF and radar signatures, security teams will determine how much of a threat the drone poses. The FAA notes that this is a matter of case-specific expertise and situational awareness, as “There are no nationally recognized standards for detection or classifying UAS at this time,” as stated in March 2022.
From there, the security team responsible for the perimeter can use either electronic means like jamming or spoofing, or kinetic mean to bring down the UAS. Today, non-kinetic techniques are more common. Some drones used in military capacities can take control of adversary UAS and safely maneuver them outside of the perimeter, and away from sites where they could damage.
Defending military base perimeters
GAO notes that the FAA has explored long-range jamming technologies for domestic military bases in rural locations, where there are few cities or commercial airports. In these places, jamming typically does not risk disrupting legitimate or mission-vital signals. Counter-drone systems also need to know what else may be in the sky, from power lines to birds.
One relatively long-term plan for a solution comes from the Modular Efficient Laser Technology (MELT) program of the U.S. Defense Advanced Research Projects Agency (DARPA) in Arlington, Va. DARPA’s MELT program seeks to direct high-energy lasers against adversary drones.
In January 2022 DARPA put out a broad agency announcement seeking a compact, scalable, actively coherently beam combined semiconductor laser source for a small, affordable laser source. Laser weapons are desirable because of their effectively unlimited ammunition magazine. Yet to put it simply, DARPA is exploring coherent beam combined tiled arrays because they enable relatively small systems. The MELT program will run for five years.
Another counter-UAS challenge DARPA is seeking to solve is enabling laser weapons to function across a broad range of power levels, from a few kilowatts to megawatts, since drones can range in size so much.
Jamming or spoofing?
At the neutralization stage, there is a key difference between jamming and spoofing. The former blocks RF and GPS communications between the drone, its operator, and its navigation system. It destroys the drone’s ability to communicate. With the latter, defenders can deceive GPS signals to the UAS’s receiver to take control of the drone. It sends a false signal that can take advantage of the drone’s ability to communicate.
Counter-jamming also is used in the chess game of attacking and defending drones. If an adversary denies a drone’s satellite navigation as in a jamming event, the drone may switch to an autopilot with GNSS-denied capability. This introduces some navigation errors, but ideally will allow the operator to maintain stability and control and eventually recover the friendly drone.
Neutralization
The Thales Group in Paris has demonstrated drone neutralization with the company's Horus-Shield anti-drone system at sporting events and around the perimeter of critical infrastructure. Also using components proven in border surveillance, it is an example of how to detect and jam neutralize drones, in this case using RF jamming.
Thales also recently announced a partnership with MARSS Group in Monaco to integrate the NiDAR C2 security platform with the drone-neutralization systems. Details on the inside of these boxes is scarce, but the partnership does show a United Kingdom initiative to keep the industry growing through the integration of counter-UAS with other security software designed to defend against homeland threats and improve situational awareness.
Companies in industry like BlueHalo in Arlington, Va., which recently acquired Citadel Defense Co in National City, Calif., continue to invest in artificial intelligence and machine learning. Citadel uses AI and machine learning at every stage of drone detection and defense in their work with the U.S. Department of Defense. Citadel’s Titan line of products can track patterns of UAS activity, including geolocating drone and pilot. It follows the trend of integrating multiple sensors, using radar and optics as well as AI analytics.
BlueHalo also emphasizes the speed of deployment for this product, saying the Titan system can be deployed in under two minutes and requires a minimum of training for operators to get up to speed. It also responds to another trend we talked about last year: swarms. A Program of Record (POR) selection awarded to BlueHalo by the DoD in August includes an automated decision engine that cues up electric countermeasures, taking the human element out of discriminating frequency-hopping spread spectrum signal characteristics.
Swarms and layered sensors
Lockheed Martin Corp. in Bethesda, Md., advertises the company's laser weapon system as a possible counter for drone swarms. ELTA North America and Aurora Flight Sciences both emphasized the importance of autonomy in the system they deployed at an Army Rapid Capabilities and Critical Technologies Office demonstration in April 2021.
“We all know warfighters are wearing multiple hats as it is, so having something connected to the network that is fully autonomous is crucial,” says Dean Nohe, senior director of business development for ELTA North America, in a statement to the Army. “[Their product] takes the network or sensor feed and assigns the right drone to the right threat. Once it gets close to the target, there’s on-board processing and on-board AI that enables an optical target lock and continues the autonomous guidance to the drone until interception.”
A 2021 report from the NATO-affiliated Joint Air Power Competence Centre notes even as autonomy improves, another important consideration is to keep a human in the loop. Human operators provide moral, ethical and legal considerations on top of an automated system.
A layered approach also is being adopted, related to the idea of sensor fusion. ASIS points out that radar and RF devices can be paired with multi-sensor EO/IR cameras with light and thermal sensors. Furthermore, the field approaches the era of AI with Convolutional Neural Network analytics, which can be trained to detect and discriminate between objects based on pixel-sized differences. Tracking software in this area needs to respond very quickly, leading to the development of specialty software for quick classification and auto-tracking.
The GAO notes that as drones become smaller and more maneuverable, counter-UAS technology will need to keep up. Counter-UAS technology could prove critical at airports, military bases, sports events, sensitive national security facilities and more.
