To content



Threat / end user issue

The versatility and commercial availability of drone technology has resulted in proliferation and adoption of this technology, most notably by insurgents. The low cost combined with ease of use makes (swarms of) small multi-copter drones an attractive platform for information collection and delivery of explosives. Numerous drone incidents and attacks in the past years demonstrate the difficulty of detection and neutralization of such low-observable platforms. Low, slow and small drones have little signatures in all domains, adverse weather performance and the lack of line of sight aggravating the challenge.

Neither radar nor electro-optical sensors can reliably detect drones under a variety of conditions (all weather, day & night, non-line-of-sight). A multi-sensor counter-UAS system fusing radar, electro-optic and acoustic sensors has the potential to yield a reliable drone detection capability. In the acoustic domain, acoustic vector sensors provide the better stepping stone to contribute to the overall capability.

Our solution

The SKYSENTRY C-UAS is under development. In its simplest configuration, it uses a single CASTLE sensor post, providing heading and elevation angles towards UASs. In such set-up, it can slew-to-cue co-located active and/or narrow field of view sensors.

In a more capable configuration, SKYSENTRY uses multiple networked and geospatially distributed CASTLE sensor posts. In such set-up, heading and elevation angles generated by the sensor posts are combined into 3D tracks and can be used for sensor data fusion as well as for triggering responsive measures.

Key characteristics

  • All weather, day and night, non-line of sight capability
  • Unattended
  • Low SWaP
  • Passive
  • Ease of deployment, one sensor post is deployed by one person in less than 10 minutes
  • Available as self-contained C-UAS system, interfaces for integration in a multi-sensor C-UAS system

Detection range and 3D localization accuracy are currently being investigated and tested. Detection range will depend on the type of drone, the intrinsic noise level of the airborne platform during flight. Initial tests have demonstrated detection range up to 250 m for a small (2 kg) quadcopter drone and up to 1 km for a small (2 kg) fixed wing drone. Manned helicopters can be detected up to 10 km range distance. Detection ranges in general depend upon weather conditions, mostly wind speed and wind direction.

SKYSENTRY can track aircraft having a wide-band acoustic signature (multi-copters, aircraft having jet engines) as well as aircraft having a tonal acoustic signature (propeller aircraft, manned helicopters).

How does it work

Each SKYSENTRY sensor post detects direction of arrival (DOA) of airborne threats. The broad-banded acoustic sensitivity is exploited by using real-time multi-frequency parallel processing techniques, effectively creating a multiple synthetic narrow-banded sensors out of a single broad-banded sensor. This can be repeated in each of the sensor posts. This approach allows for correlation of DOAs (for each synthetic sensor), resulting in a robust and reliable 3D localization and tracking capability.

The 3D tracks are plotted on a map display in the command post. In addition, track data is available to 3rd party software applications via an API, enabling high-level sensor fusion with tracks generated by other radar and/or electro-optical sensors. Alternatively, low-level sensor fusion can be applied, merging DOA vectors and range information of all sensors, jointly generating a multi-sensor track. Such low-level sensor fusion is expected to yield better results than high-level sensor fusion.

Product set up

The SKYSENTRY system in standard set up would comprise out of the items listed below.

  • To be defined number of sensor posts, including:
  • Command post, including:
    • 4 AMMS - sensor nodes per CASTLE
    • Acoustic Master – computing device
    • Weather station
    • Georeferencing device
    • Manet radio
    • Battery box
    • Ruggedized laptop
    • Manet radio
Case Study External Small Drones To Threaten Deployed US Forces June 2020
3D acoustic situational awareness