How to cope with the drone challenge?
Few have missed the recent headlines about drones causing chaos for airports around the world. Drones have forced major airports to come to a complete standstill on more than one occasion, resulting not only in inconvenience for passengers but also in significant economic damage. Why are drones so difficult to detect for traditional radars and is a solution at hand?
Drones, also referred to as Unmanned Aerial Vehicles (UAVs) are widely available in hobby stores at a low cost which means anyone can get hold of one. This has resulted in new challenges such as the issue of airport closures but also of new types of threats in military conflicts.
A growing challenge for airports
Despite tightened regulations, reports of drones near airports are frequently causing security alerts that result in airport closures. A collision between a drone and an aircraft could have fatal consequences, especially in association with take-off and landing. So why aren’t the drones detected and identified earlier by airport surveillance? The underlying problem is that many airports solely rely on the national radar surveillance service, which is not equipped for this purpose. And in cases where local surveillance radars are used, the radars typically fail to detect drones as they are programmed to remove radar clutter such as birds, which have very similar movement patterns to drones. To solve this problem, engineers at Saab have been busy testing a solution that is now being finalised as part of the standard Giraffe surveillance radar offer. The feature is referred to as the Enhanced Low, Slow and Small (ELSS) capability.
In the early ELSS tests the radar detected the drones much better than traditional surveillance radars. The challenge was to distinguish them from birds – the radar picture could be cluttered by hundreds of birds.
“We have now developed advanced algorithms that that can identify drones even in a flock of birds, says Torbjörn Wolffram, Saab’s business unit Radar Solutions. “The false classification probability can be kept on very low levels while still being able to classify drones with a high probability”.
In order to bring the false drone report down to virtually zero, the radar may be paired with an optical sensor that enables the classification. Saab’s ELSS capability can be used with any of Saab’s Giraffe and Sea Giraffe radars and since the solution is software-based it is also possible to upgrade existing Giraffe radars with this new capability.
“This UAV detection capability is available now, Wolffram continues. Using the ELSS capability with the Giraffe AMB radar, drones can be identified and classified from distances of 10-15 kilometers and with Giraffe 4A the range is even longer. This makes ELSS ideal for use at airports, where successful identification and classification of drones is fundamental in order to deal with the problem”.
Drones as military game changer
Drones are also becoming a game changer in military operations where they are increasingly incorporated into the armed forces and can be used for surveillance or signals intelligence.
“Using drones for military purposes open up new possibilities, Wolffram says. But this also means that we are facing a new generation of threats that are difficult to detect and classify with traditional radars. Our ELSS technology can detect these threats with very low false alarm rates, in the region of 1-3 per cent”. Wolffram explains that there is great demand on the market for the counter-UAS capability both from industry and military actors. “Our ELSS capability offers not only a longer range but a much higher classification performance compared to competitors. Unlike other available solutions, ELSS also maintains performance for drones that are not using communication links. Many of the competing solutions rely on these links for detection”.
Part of the key to achieving this is that Saab’s surveillance radars were originally designed for Ground-Based Air Defence (GBAD) which requires high update rates as well as capability to detect very small objects. “We have added the capability to see very slow targets”, Torbjörn Wolfrram concludes.