For some inexplicable reason, memories of these bits of kit popped into my consciousness yesterday. I only ever saw them in my Inf Junior Leader days. Were they among those bits of shiny kit that never left the shelf? Or did they never make it that far? TOBIAS (Territorial Observation By Intruder Alarm System) used geophones connected to a monitor by wires. It picked-up tremors caused by footfall, these registered on the swinging-needle dials. The operator was supposed to be able to detect the direction and number of people moving from the amount of needle swing. IRIS (Infra-Red Intruder System) was a sort of Hollywood-style beam system that gave an alarm when the beam was broken.