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A new approach regarding the use of sensors for intercepting intruders has been suggested. The method, advocated by Applied Research Associates (ARA), involves strategic deployment of the company’s Pathfinder seismic-acoustic sensors.

Asymmetric placement of the sensors is in contrast to typical perimeter security systems, which are linear: Sensors are distributed at specific intervals along a perimeter and require infrastructure to communicate back to a control centre.

Instead, asymmetric placement involves fewer sensors that are hidden strategically and tactically in areas to address known vulnerabilities and threats. At a border, small, covert sensors might be positioned in a “dead space” that isn’t otherwise monitored, or along a specific route intruders are known to use. Using an asymmetric approach to perimeter security is more efficient and cost-effective.

According to, the sensors can then track and map an intruder’s movement, locations and intent. Knowing the location of intruders enables personnel to intercept them at a further distance, even before they reach a perimeter; meanwhile, the sensors continue to operate covertly and unseen by future intruders. The more focused approach allows an end user to address a specific known or suspected vulnerability in an immediate area of concern, rather than taking a broader approach typical of perimeter security.

The asymmetric approach is enabled by a longer wireless transmission range, a key feature of the Pathfinder sensor. A proprietary RF radio sends transmissions 10 to 12 kilometres (6 to 8 miles) with no gateways or receivers (up to 20 km [12 miles] if the receiver and antenna are elevated]).

Pathfinder is the second generation of a sensor developed in a DARPA (Defense Advanced Research Projects Agency) initiative.

Pathfinder, a new generation of the E-UGS technology developed for the commercial market, has better machine-learning algorithms, is therefore “smarter,” and provides higher detection probability and fewer false alarms. Battery life has been extended from 3 months to about 6 months for the smaller Pathfinder Mini sensor, which has the form, fit and function of the E-UGS sensor with improved probability of detection and lower false alarms.

An Android app provides a map showing activity reported by the sensors, or the information can be integrated with a variety of physical security or command-and-control systems.

The sensors provide early-warning detection of intruders where cameras and agents cannot detect them. The sensors are covert, buried in the ground and communicate wirelessly, so there is no infrastructure in the immediate area to tip off a sensor’s location. Radio waves of data packets transmitted from the sensors are masked so that they remain below the ambient noise floor – i.e., they are undetectable.

E-UGS sensors are used ad hoc in the military battlefield to provide information on movement of intruders, locations and intent. The small sensors can be buried quickly by a soldier. They are also “expendable” – the E in E-UGSs – and considered almost disposable or consumable, typically used only once and not recovered (in military situations). In longer-term deployments, more typical in commercial applications, the length of service for the newer Pathfinder sensors depends on battery life (and changing batteries when needed).

Enhanced and adapted for commercial usage, Pathfinder sensors can be used in a variety of vertical markets, especially critical infrastructure protection, as well as border protection. In the defence and Homeland security realm, they are used by international governments (Latin America, Africa) – protecting power grids, transmission lines, natural gas and oil pipelines.