Qinetiq is offering UGS which could be deployed by rockets, vehicles aircraft or manually emplaced. Its primary sensor is an acoustic array used for initial location and tracking of targets. A low cost thermal imager producing panoramic survey of the area is used for target classification. 
The main advantage of this UGS is its network sensing – the system uses emerging, self organizing networking to link several sensors to provide persistent surveillance and targeting over a large area. Networking also helps reducing false alarm rate, by having several sensors “agree” on the identification of a target before an alarm is triggered. By generating “fixes” from different positions, by several sensors, the system can generate accurate target positioning, and effectively track a target as it moves from one location to another.
