As unmanned aerial vehicles (UAVs) advance, the wireless sensor networks that they use also are evolving. An example is a new wireless ground sensor system. It promises to provide unmanned vehicles with ubiquitous coverage and constant surveillance of designated areas.

The Self-Powered Ad-hoc Network (SPAN) from Lockheed Martin is a multi-purpose wireless platform that utilizes a network of sensor nodes. Each node, placed on or in the ground or in a mesh arrangement, transmits relevant data to the next node until the information is ultimately forwarded to a wide-area communications link. Each of these lightweight, “palm-sized” sensor nodes can be easily fitted into a rock camouflage enclosure to make detection difficult. In addition, the low-power mesh networking reduces the electromagnetic (EM) signature. On-board data processing minimizes the occurrence of false alarms. SPAN only transmits to the UAV if there is a sensor reading of concern. During a mission, the network automatically prompts the UAV’s high-precision sensors to further characterize an alert. This eliminates the need for a remote analyst while allowing UAV operators to focus on identified threats instead of waiting for potential ones. The system, which supports multiple backhaul communications including satellite communications, uses commercial off-the-shelf (COTS) components.

For its power source, SPAN relies on thin-film energy cells that harvest energy from the surrounding environment. There are two power configuration options: perpetual and expendable. Perpetual power includes sensing nodes and a gateway utilizing energy harvesting and a thin-film battery. Expendable power includes sensing nodes and a gateway with a replaceable battery. Both configurations include a ruggedized handheld computer for local monitoring and sensor emplacement.