Some of the earliest work on fiber optic distributed acoustic sensing suggested perimeter security as an application for this technology. Sensing cables are buried along boundaries, typically 0.2–0.4 m deep, to detect footsteps or approaching vehicles; the fibers can also be included within fences to give alarm on signs of people climbing over, or cutting them.
In practice, however, it is not sufficient to raise an alarm when the local condition of the fiber changes, indicating a disturbance. The need for intrusion detection is better stated as having a high probability of detecting one of the event types that are pre-defined as threats whilst having a very low probability of alarming on conditions that are not threats. The system must be able not only to detect an event characterized by a change in the back-scatter signal but also apply higher levels of processing to discriminate between benign events and genuine threats.
The problem is, of course, more challenging in fiber sections that are habitually noisy, for example, bordering roads or close to built-up areas: the events that precede a threat might be the approach of a vehicle, followed by people walking near the asset to be protected and finally digging. In populated areas, there are many innocent explanations for signals like these. In addition, the increased ambient noise from non-threatening events makes detecting and classifying real threats much more difficult, especially with a system with random transfer functions, such as amplitude DVS.
Fiber optic distributed acoustic sensing system (FOTAS) includes an artificial intelligence software that significantly reduces nuisance alarms using reliable algorithms that decipher and classify the type of intrusion in real time. FOTAS models provide either single channel or dual channel which is cut resilient. Users can be notified of alarms via text or email, and by leveraging GPS coordinates, the system can pinpoint the location of a security breach within seconds. With this information, asset owners can increase the effectiveness of response mechanisms.
FOTAS is open-source software based, thus allowing easy alterations to perimeter adjustments and/or changes to the number of zones being monitored. The system is also easily integrated with other systems and sensors, such as CCTV cameras and VMSS, for a more robust security management solution.