Military Embedded Systems

Counter-drone technologies are evolving to "counter" countermeasures


April 09, 2019

Sally Cole

Senior Editor

Military Embedded Systems

Counter-unmanned aircraft system (UAS) technologies are focusing on a multilayered defense. They’re also being tasked with providing a “counter” to countermeasures.

Drone technologies are evolving rapidly and, not surprisingly, counter-drone technologies are as well. The U.S. military is currently embracing multilayered counter-drone approaches to deal with the threat drones pose, but no silver bullet approach exists yet that can detect and mitigate every threat.

“Hundreds of millions of dollars are being spent on counter-drone systems today – ranging from military drone mitigation to small drones,” says Mike Blades, vice president, Americas, Aerospace, Defense, and Security for Frost & Sullivan (New York, New York). “Most of the efforts center on small drones because that’s proliferating the fastest.”

Raytheon’s defense customers are “likening drones to the improvised explosive device (IED) situation 20 years ago, when we saw an adversary take a readily available technology and weaponize it in a low-cost way,” says Todd Probert, vice president of Raytheon Intelligence, Information, and Services (Dulles, Virginia). “This is a similar situation in which the cost of the technology has come down so rapidly that the influx of this capability on the marketplace has given adversaries the ability to do nefarious things with them.”

Threats from drones have become “much more prevalent with the proliferation of inexpensive drones,” says Dave Bessey, assistant vice president of business development for SRC (North Syracuse, New York). “For example, the disruption of air travel or small unmanned aircraft systems being used in insurgent operations for surveillance or to deliver deadly payloads. This threat is also becoming autonomous – with a lack of communication signals – and is undetectable by RF, which means that other layers of defense are now required.”

Right now, SRC is actively developing on-the-move sensor suites for multifunction electronic attack and surveillance, as well as advanced cameras and optical tracking. “To enhance all of our technology, we’re investing in artificial intelligence (AI) and machine learning,” Bessey adds.

Detection of targets

When it comes to counter-drones, “you need the capabilities to detect, track, and positively identify a target before you can engage,” explains Don Sullivan, chief technologist of directed energy for Raytheon’s Missile Systems (Tucson, Arizona). “So you need what we refer to as ‘full skydom’ coverage: it has to be 360 degrees in azimuth, and then from below the horizon to straight up zenith in the sky. If you don’t have that capability, then you have a vulnerable path to the target not being covered and it can become a major issue.”

Another consideration is that your response should be commensurate with the cost of the target. “Sending an interceptor that’s going to cost you tens of thousands of dollars to take down a $200 or $500 drone isn’t a good approach,” Sullivan says. “It may be necessary against some high-value assets that you’re trying to protect, but it certainly isn’t an economical way of countering the threat. For that reason, both electronic warfare and cyber and directed energy are good approaches because you’re engaging targets for as few dollars per engagement as possible – if you take into account maintenance and operation costs. So the military is looking at nonkinetic solutions vs. kinetic solutions for most counter-unmanned aircraft system (UAS) capabilities.”

Blades says he expects the military to continue to invest in more advanced capabilities like AI to help with detection. “They want to be able to detect drones really far out, so they need radar that can detect small things flying low and fast,” he notes. “EO/IR is good too, because it allows you to do payload detection. Once you have this thing on your radar you can point a camera over that way to see if it’s carrying something bad and, if it is, hopefully you have some sort of AI able to detect that automatically so you won’t need to have a person sitting there looking at every drone detected.”

Mitigation can focus on directed energy

On the mitigation side, expect to see a continued focus on directed energy such as laser and microwave counter-drone technologies. “Microwave technology isn’t as destructive as lasers,” points out Blades. “You’ll usually want to be able to do forensics on something that you shoot out of the sky to determine who sent it and why. The microwave will simply fry the electronics so that it can’t operate; it won’t destroy the aircraft and burn it up like a laser would.”

Raytheon offers both laser and microwave counter-UAS systems. Their high-energy laser weapon system (HEL WS) has already shown that it can knock down more than 40 UAS targets coming at it. “The Air Force and Army are mostly interested in Class I and II UASs, which are the smaller systems that you normally see like the small quadcopters and fixed-wing UASs being used by terrorist groups overseas for attacks,” Sullivan explains. HEL’s main advantages are that “it has a fairly long range within the 3- to 5-km range, on the order of a 10kW laser, and can take out individual UASs fairly rapidly. They can go after ISR [intelligence, surveillance, and reconnaissance] UASs that are there to search for and locate potential targets for the adversary.”

Raytheon’s high-power microwave (HPM), called Phaser, is primarily custom-built and has advantages that are complementary to HEL. “It doesn’t have as long a range (which is classified) as HEL, but because its beam is more akin to a searchlight than a laser beam it can take down UASs simultaneously within its beam,” Sullivan says. “We’ve demonstrated Phaser several times. Because of the complementary nature and the advantages of engaging targets at the speed of light and being able to specifically with the Phaser take out swarms of UASs simultaneously, the Air Force wants additional demonstrations of both of these systems.” (Figure 1.)

Figure 1: Raytheon’s high-power microwave (HPM), called Phaser, is primarily custom-built and has a beam that is more akin to a searchlight than a laser beam so it can take down UASs simultaneously within its beam.

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Multilayered counter-drone approaches

Many counter-drone approaches focus on radio frequency (RF) because most drones use some sort of RF command and control link, but now it’s being combined with electro-optical/infrared sensors, radar, or acoustics for a more complete multi-sensor detection capability.

“Companies are forming partnerships with others who specialize in areas they don’t. Sensor makers are partnering with companies that make jamming guns or net guns, or directed energy and lasers on the defense side,” Blades says.

Counter-UAS solutions “are expanding to include fixed, transportable, and mobile configurations,” Bessey says. “Military customers will ask for more autonomous systems because they want systems that are open to integrate with other sensors, such as acoustics, depending on the environment.”

What do you do once you gain lots of situational awareness from all these sensors? To help make it more useful, Raytheon has created a command and control mode called Windshear, a counter-UAS system, which is a platform to plug in other sensors – think radars and optical systems – to help get a better picture of what’s going on within your airspace.

“Windshear is plugged into large-scale air traffic control radars, but it’s purpose-built to go to that small space as well to look at that 100- to 1000-foot range to understand what’s going on within that environment,” Probert says. “Then we marry it up with effectors. So if you have an intrusion, in the case of a UAV entering an airport’s airspace, maybe the first phase of the effectors would be lights and sirens to make the operator aware that it’s a restricted space and give them the option to move out of it.”

A layered defense beyond that would also be preferred, and Raytheon has RF techniques that allow it to jam the communications systems of a large class of these unmanned systems, which might be the second layer of defense. “Beyond that, we’ve got GPS jamming capabilities and cyber effects that can take out the GPS these systems use to navigate, or the operator can take positive command and control of those systems to ensure a safe landing or steerage out of a public venue,” Probert adds.

Windshear has been demonstrated with battlespace effectors and Raytheon’s high-energy laser; it’s also been part of demonstrations where a kinetic effector like a missile might be used as well.

Raytheon is dealing with all of the military services, and they’re all looking at a multilayered defense. “Think of a set of range rings around the point you’re trying to defend – whether it’s a fixed point or a convoy in motion,” Sullivan says. “You’d like to be able to do that within these rings.”

For example, one UAS system Raytheon has developed for the Army is called the Coyote. It has a very small kinetic warhead, but a very advanced seeker that gives you the ability to attack individual drones. “It can go out for quite a long range and inside it you’d have something like Windshear and a high-energy weapons system, which provides a ring 360 degrees around and full-sky coverage that allows you to take out UASs within that secondary ring,” Sullivan adds. “Then, when you want to take out large swarms simultaneously, you’d use the HPM Phaser to defend the point within the closest range ring.”

The problem of swarms

Swarm technology – with numerous drones working cooperatively together on a mission – doesn’t need to be very advanced to pose a serious threat.

Swarms are becoming an increasing issue, and “if you watched the Olympics in South Korea you saw the demonstration of many UASs flying in formation,” Sullivan says. “And the Chinese had a demonstration of 1,374 drones, the world record, which shows that you can have a very large number of these types of systems. Both military and civilian authorities are quite concerned about the potential of swarms attacking targets.”

What is likely to become a target? “In general, the U.S. worries about large groups of people at big events, in stadiums, parades, and on main operating bases where high-value assets in terms of aircraft and other defense systems are located,” Sullivan adds. “Of course, forward operating bases are an issue, where the concern is mostly about surveillance, but there’s a potential for swarming attacks as well.”

“Even if a bad actor launches 50 drones at the same time, not working together, it’s bad because it’s an asymmetric threat,” Blades says. “You can buy 50 drones for $50,000 and inflict millions of dollars of damage. Drones have very unsophisticated launching mechanisms, and bad actors can select waypoints and let them fly and drop on targets. Even if it isn’t a swarm, with small ammunition like grenades or 40-mm shells, if 20 or 30 drones are coming at you, it could get real bad fast.”

A bunch of drones coming at you poses a threat, but a swarm coming at you is much worse because they will be able to change to adapt to whatever you do to counter them. “The idea behind swarms is to coordinate and cooperate to make the attack more lethal,” Blades notes. “So the military needs to be able to take out multiple drones simultaneously.”

Hostile swarms will likely “become a reality, because there are reports of countries already testing swarm capabilities,” Bessey says. “SRC’s technologies, including Silent Archer and SkyChaser, are engineered to detect, track, and mitigate a single drone or a swarm. Many of the existing technologies such as netting or jamming drone guns aren’t capable of mitigating a swarm. The more sophisticated the swarm technology is, the more difficult it is to neutralize them.” (Figure 2.)

Figure 2: SRC’s counter-UAS technology shown conceptually on a military Stryker combat vehicle. Image courtesy of SRC.

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Countering the countermeasures

Once it becomes possible to counter UASs, the next step is to find a way to counter the countermeasures.

“There’s a sort of little arms race going on now – so many counter-drone systems and approaches are available,” Blades says. “Drone makers are asking, ‘How do we counter that counter?’ and ‘What can we put on our drones so they can’t see or hear us?’”

A small industry is already emerging to make drones more difficult to detect, Blades notes, using everything from antispoofable GPS antennas to new ways to reduce the acoustic signature of drone propellers so you won’t hear that classic high-pitched drone noise until it’s much closer or you won’t hear it at all.

This is just the beginning.