UGS systems utilize a combination of detectors, including seismic detectors (geophones), used to identify ground vibration caused by vehicles or pedestrians. Magnetic detectors monitor movement of metal objects such as weapons or vehicles. Acoustic sensors are used to detect targets by specific acoustic signatures (noise of engine, tracks etc) while passive infrared (PIR) sensors detect movements of objects in a narrow field of view. Input from all these detectors is collected by the gateway, processed by its on-board signal processors. When signatures are correlated into verified target detection, an alarm is triggered and transmitted automatically by radio to a central monitoring point in order to alert reaction forces on the suspect area.
In certain situations, other sensors are required to verify an alarm triggered by non-imaging sensors. Such verification will most commonly utilize an imaging sensor. A typical configuration of such system is the Rheinmetall Defense BSA. A similar function can be provided by the Covert Unattended Ground Imager, (UGI-C). This man portable, persistent all-weather system is comprised of a thermal camera triggered by PIR, taking snapshots of nearby motion events. The captured images are compressed and sent as short 3.5 animation movies over non-line-of-sight RF communications link. Other systems currently available include Terrain Commander, which can be operated autonomously or by remote control.
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