ok all you old and bold Back in the70s, I was a REME tels tech and I recall working on 2 bits of intrusion kit while serving in an inf LAD. One was IRIS, Infra Red Intrusion System iirc. and another system that employed buried geophones connected to a control box that would record motion sounds as a count. I cannot, for the life of me, remember what this sytem was called or its acronym. Can anyone help please?