Counterdrone Factbook

With counterdrone technologies rapidly coming to market to address the quickly growing drone threat, it becomes increasingly difficult for the prospective users of the technology to separate effective and value-for-money products to a very large number of inferior alternatives.

Broadly speaking, there are three types of providers:

“Mom-and-pop” small start-ups

Many of them have no product (the telltale sign is no product images on the website – if it exists – or only CGI drawings), or very basic prototype, with a couple of employees. As a customer, the key issue with working with such people (besides the lack of product or low quality of thereof), is uncertainty around product support, and ongoing investment capability to continue refining the product as the industry develops. A certain minimum scale is critical to not only invest in the product, but also conduct marketing and collect intelligence on customer requirements, to incorporate into the product

Defence primes

The 800 pound gorillas in the space, with significant capabilities, the primes have so far focused (for most part) to repurpose products developed for a different scenario, eg mortar detecting radars and IED jammers. Key issues include very high end pricing (a multi-million dollar sensor for mortars may be perfectly fine, but may often be too pricey for customers in the counterdrone space). The products can be very restricted for sale (eg the JCREW IED jammer is considered unlikely to ever be able to be available outside of US Military), and often developed in multi-year programs funded by the customer, hence having much lower responsiveness in a fast evolving counterdrone industry.

Middle Ground

In the middle between the above categories sit what may be considered “sweet spot” of suppliersd - enough funding base and scale to address the customer requirements, not too large and still nimble. Many of names in this section evolved from adjacent categories (bird detection radars for airports, radars for ground security, etc). Few are specifically focused on counterdrone sector only. This affords the benefits that full-time focus brings – faster development of tech, better understanding of customer requirements etc.

What to look for in a counterdrone product

Multi-sensor detection solution

The main drone detection methods today include radar, radiofrequency and acoustic sensors, as well as optical and thermal sensors for identification.

More exotic detection sensors such as LIDAR exist, however have not been widely proven in field applications to be effective at this point.

It is important to understand that no future-proof “silver bullet” exists, and the role of the counterdrone systems and manufacturers is to keep up with the drone technology, and evolve with it.

What to look for in a radar

A radar is effectively a motion tracker. Key parameters, in simple terms, include:

• resolution: it is critical for the radar to be sufficiently fine resolution to detect small drones (DJI Phantom grade and below), at meaningful distances (close to 1km). Numerous radars have been design to detect large shiny metal objects (aka planes, helicopters) and are less suited for detecting small, carbon body objects flying closer to the ground (drones)
• azimuth coverage: horizontal coverage angle. This normally ranges from 90 degrees to 360 degrees, with multiple radars used to deliver a wider angle, if required, for sub 360 degree units
• vertical angle: this is greatly underlooked by a lot of customers. A lot of radars on the market are narrow (10-30 degrees), meaning significant blind spots, especially as the drone gets closer. While a 90 degree vertical coverage is not usually needed (ie detecting a drone directly overhead from the sensor), 40-80 degree detection is considered optimal
• 2D vs 3D: 3D radar has several advantages, including giving the elevation data on the target, as well as ability to reduce clutter but filtering objects past certain heights (and thus eliminating ground based false alarms) Portability: unless a fixed installation, formfactor and ability to mount relatively quickly and easily on a mast is important Moving vs fixed panel: less moving parts is preferable, as reduces wear and tear and likelihood of things breaking

Certain manufacturers have been working on software features for a radar to differentiate between drones and other objects, such as micro-Doppler, Artificial Intelligence, etc. While encouraging concepts, noen of those technologies are reliably performing at present, and the user is advised to always see the technology themselves in action. It is worth noting that micro-Doppler effect is expected to reduce significantly once the drone blades will be required to be enclosed (an expected safety development, given reported incidents of drone blades creating injuries etc)

What to look for in a radiofrequency sensor

RF sensors work (for most part) by matching drone communication protocols to a signature in the Rf sensor library. Multiple drone models sharing same protocol (eg LightBridge, Occusync etc) will map to same signature. The desired features are:

• Reliable mapping protocols with a large RF library, to give large probability of detection and low false alarm ratios (note: certain false alarms such as IP cameras, may be unavoidable, but should be able to be whitelisted by the software)
• Azimuth and vertical coverage angles (similar argument to that for a radar, as abovementioned)
• RF DF (direction-finding) capability – as opposed to an omnidirectional or “sector” alarms. RF DF gives a narrow beam (couple degrees) that can be used to point in the direction of the drone, and also triangulate in a reasonably precise manner, with 2 or more RF sensors
• With RF sensors generally much longer reaching than radar (up to 5km in a low clutter situations), this ability to triangulate on a target without a radar, gives a significant advantage from cost perspective
• Passive nature - no interference with other devices, and more difficult to discover by “enemy forces” through Rf emissions
  
  

With the coming advent of LTE controlled drones, Rf sensor technology will require to continue to evolve. Another common question is performance of the RF sensors for “autonomous” drones. While many so-called autonomous drones still emit telemetry and video data, making it detectable to the Rf sensor, such drones with an SD card (or similar) can be much more invisible – thus requiring reliance on other sensors to Rf.

What to look for in an acoustic sensor

There are two types of acoustic hardware for drone detection generally available today – arrays and single-microphones. Arrays give advantage of more precise location of the source, however significantly more expensive vs single mic hardware, and still materially worse performance compared to radar or Rf sensors.

Acoustic software works by removing the background clutter from noise made by the drone blades and engine, and comparing it to the database of acoustic signatures. Similar to the Rf sensor, multiple drones will likely map to each signature, and the library needs to be regularly updated to stay up to date. It is worth noting that some of more recent drones (eg DJI Mavic Pro) are significantly quieter compared to earlier generations of drones, making the job of acoustic sensors more challenging.

Acoustic sensor technology is expected to respond well to AI, however to date has not been incorporated in a meaningful way.

Optics and thermal

Optics and thermal are common parts of drone detection systems, however it is important to understand the distinction between detection and verification. Camera and thermal performance is a trade-off between FOV (field of view) and distance – greater the angle that is being monitored, less the distance. Even best quality cameras will not detect a drone as anything more than few pixels even at couple hundred meters, with a 90 degree plus field of view.

Thus the best application for camera/thermal is slew-to-cue from the detection provided by the primary sensors. A dot on the map (as opposed to general direction) is very helpful, as allows the camera to auto-zoom. At this point, video analytics can kick in for further identification (or an image taken to act as proof of evidence of drone intrusion).

What to look for in a mast

Last but not least, how the sensors are mounted is important. Pump-up/hydraulic masts may look impressive during demos, but have a tendency to break down in-field. As with other equipment, less moving/motorized parts translates into more durable hardware which is less likely to break in-field. A durable mast with a manual mechanism for extension, is recommended. A mast should also have capability to be firmly attached to the ground (and with cords for additional balance), with no swaying in the wind. Permanent installations to infrastructure such as telecommunications towers, often works well.

Defeat solutions

Broadly speaking, the defeat solutions available today include kinetic/”hard kill” (bullets, nets, lasers etc) and non-kinetic/”soft kill” (jammers, cyber/hacking).

It has generally been accepted that soft kill is the better solution due to:

• Reduced collateral damage (eg a bullet flying past a drone and hitting another object, drone’s payload exploding upon kinetic impact etc)
• More reliable targeting (a jammer generates a cone of impact that is much easier to catch the drone with, versus a bullet or a net, especially as the distance to the drone increases)
• Ability to defeat a swarm/multiple drone attack (as a jammer covers an area, and multiple jammers can completely lock the airspace)
• Ability to recover drone for forensic investigation

Jammers are considered a superior technology to “hacking” as they are a universal protection – targeting bands on which the drones operate, as opposed to relying on having a library of hacks for various communication protocols, each of which can be closed up as the manufacturers continue to make the communication links increasingly secure. Some of the militaries today are starting to look at systems with both soft kill and hard kill capabilities.

The jammer works by sending a strong signal on same frequency band as the drone uses to communicate with the controller and GPS satellite, forcing the drone to go into a pre-set emergency protocol. This generally involved flying back to starting point if the GPS connection remains available, or landing on the spot is the GPS linkage is also severed. In the latter case, some drones may also freeze and hover at a small distance above ground, until their batteries run out.

The drones today communicate on 2.4Mhz and 5.8Mhz bands for most part (for both navigation and video), with some drones utilising 433Mhz and 915Mhz bands. These are considered “unallocated” bands across the world (as opposed to say cellphone or emergency broadcast frequencies), and drone manufacturers (along with wifi, radiofrequency controlled toys, radios etc manufacturers) are required to stick to those bands by law. Changing the communication band “in a garage” is very difficult for a non-State agent (unlike, say, changing blades/engine or adding custom payloads).

Jammers generally come as directional (“cannon-like”) and omnidirectional. As it takes approximately 60 seconds to defeat a drone (for the comm links to terminate and the drone commence the response sequence), systems that can defeat drones from multiple directions at the same time, are considered optimal. Handheld jammers, especially in shape of rifles, have become popular directional jammers in recent period, with ability to effect the target at a greater range (for a given amount of portable jammer power) and a reduced interruption of radiofrequency spectrum outside of the intended direction.

GPS/Glonass jamming is also helpful as an option to triggered the abovementioned “emergency landing” mode.

A common question arises as to what happens to “autonomous” drones. Severing their Rf links will cut the video feed to the operator immediately, and jamming GPS will trigger emergency landing, similar to the normally navigated drone.

As of this time of writing, no reliable “inertial navigation” exists in the way that the drone continues to travel to its target location while jammed.

As a jammer is an emitter device, safety for use certifications from an accredited lab are important.

A note of caution is to be aware of “mini jammers” coming into the market now – very short, handgun-shape products. Power of a jammer links to size of its “engine” as well as size of the antennas. Even sophisticated jamming designs tend to produce a weak result, once they are too “minituarised”. Staged demos will often look impressive, but the customer is always encouraged to do own field trials.

Control panel

An easy to set up, understand and use control console is critical in the environment where the user is not expected to be deeply technical.

Good control systems combine ability to work completely standalone, and also connect to a cloud for updates and remote assistance, if required, in a secure manner.

Legal restrictions

This report does not constitute legal advice, and readers are urged to seek own advice on legal restrictions regarding purchasing and using counterdrone technology.

With detection solutions, the main concern is privacy breach – sensors recording and storing data without consent of the audience. This varies between locations, types of sensors, how the data is collected, stored and shared, and who is using the sensors.

With defeat solutions, step 1 is whether its legal for the user to apply counterdrone products. A user can be barred from any counterdrone products (eg FAA prohibits interference with drones in the US, on the basis they are treated same way as ordinary aircraft), or around regulations regarding a specific countermeasure (eg FCC and similar communication authorities around the world restrict interference with radio waves for most customers. As a general rule of thumb, non-government customers in most countries cannot jam. Government and military users have own protocols, which exist both for domestic use (eg only at certain military base locations in the US) and forward deployment overseas. For yacht owners, container ships, offshore oil rigs etc, Law of High Seas may apply.

Both detection and defeat are subject to any export/import restrictions for the sensor/defeat technologies. This may include US or foreign ITAR, and non-ITAR export restrictions – many of such technologies require either (or both) export and import licences from the relevant Government agencies.