http://www.nzherald.co.nz/section/story.cfm?c_id=5&objectid=10344158
"If you've ever wanted to know if prison inmates are gathering for a riot, then Paric may have the technology for you. The Auckland-based company's positioning system works by attaching radio-transmitting tags to individuals or items. The tags emit a simple radio frequency pulse - similar to that found in a car alarm keyring - that receivers locate. The system then tracks positions, accurate to within half a centimetre, and produces a continuous picture of the movement of the tagged individuals or items. "
