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Threat / end user issue

The rapidly increasing availability and affordability of low, slow and small unmanned aerial vehicles pose a concern for both the homeland security and military authorities.

On the sensing side, conventional air surveillance radars do not cover the lowest layer of airspace. The 2019 attack on the Saudi oil refinery a vivid proof.
Furthermore, as radars need a line of sight, their use is limited in an urban environment. Last but not least, as radars are active, their use in a peer to peer conflict is problematic.

Critical infrastructure may become under attack at any point in time, requiring permanent protection. It fuels the need for unattended sensors.
In a peer to peer conflict, with the ground vehicles being the sensor platforms, there is limited room on the vehicle deck for dedicated counter UAS sensors.

For each sensor category, multi mission capabilities are required that protect the vehicle itself as well. In general, there is consensus that sensor fusion is needed to handle these threats.

Our solution

The characteristics of the CASTLE sensor node make the CASTLE suitable for both static unattended use and multi purpose use while mounted on either manned or unmanned platforms.

For the permanent protection of critical infrastructure, low SWaP CASTLEs can be used in an unattended mode, the way of deployment above all dependent upon the response time needed in case of an event.

For short time protection, for instance a president visiting a market square, the rapid (less than 10 minute) deploy ability of a CASTLE sensor post is crucial. The shape of the CASTLE assures covertness, not causing unwanted concerns to the public.

In a military conflict, the CASTLE can host a variety of firmware that also provides other capabilities to the military, thus reducing the investment costs and vehicle deck space needed to counter the threat.

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

The CASTLE sensor post hears all around in a full hemispherical bubble and is acoustically broad banded, capturing frequencies in the entire audio spectrum.
On the sensor post level, the SKYSENTRY firmware processes acoustic signals that vary in time and space.

By dividing the entire frequency spectrum into so-called frequency bins, the Direction of Arrival for airborne threats is determined for a number of frequency bins. The more arrows that point in a certain direction, the higher the likelihood of the presence of an airborne threat.

The bearing and elevation information obtained can be used cueing another sensor or an effector.
When the CASTLEs are networked, SKYSENTRY firmware provides a bubble in space and time around the airborne threat.

Product set up

Deployment of a SKYSENTRY system depends upon all upon the requirements of the overall system.

Do drones cause nuisance or do they pose an imminent threat that need a certain minimum response time?
The CASTLEs can be used to cover an area or to fence a secured perimeter.

The intermediate distance between the CASTLE sensor posts depends upon the detection range versus the kind of UAS threat expected.

Additional information

Microflown AVISA drafts numerous white papers and other documents that are only available upon request though. Please contact us directly to request additional information based on your interest.

3D acoustic situational awareness