“Smart gravel” - Sensors for battlefield applications*

We propose the creation of a ‘Smart Gravel’ system for military monitoring and security sensory purposes. A
set of objects that look like gravel or small rocks would be dropped at various locations along a path, perimeter
or area of surveillance. Dropped at approximately 10’ intervals, these contain selected sensor(s) and report back
their findings by radio. The entire set of pebbles in a location self-form a communications network, a chain that
is longer than the separation distance between any two pebbles. A centralized ‘stone’ would collect the
information and forward it to another site or to a satellite for processing.

The pebbles would be powered by hearing-aid sized batteries, either fixed-use or rechargeable. Options to
recharge the latter include photovoltaic, RF, induction (for re-use) and environmental sound. Ideally,
Commercial Off-The-Shelf (COTS) chips would be used for the system, to minimize initial costs.

The design flow would be a proof-of-concept system based on fully-packaged chips. After the system has
been brought to operational readiness, the ‘gravel’ would be repackaged to use Chip-On-Board (COB)
packaging. The final envisioned size would be a 5mm cube, or less (limited by power source).

Each gravel can transmit obtained data at designed times or conditions. When neighboring pebbles send data,
it is received and then stored and/or forwarded ‘up-line’. The design of the ‘rock’ data concentrator differs in
power and capabilities from the pebbles, and is based upon greater battery power. As such, it can also support
GPS.

* proved conceptually only