Automatic doors will set off radar detectors too.
Not many roundabouts have them ! The detector is the Origin B2 so it's very much at the high end of the market. Perhaps I should add that I drive around 60 miles to work and back through villages, traffic lights and past all sorts of emission sources but absolutely nothing else will set it off.... other than a policeman gainfully employed (not) in generating revenues for Gordon Brown.
why should it respond to "the infra-red end of the spectrum"?
duhhh.. sorry... I've been in the office since dark o-clock this morning. It's a laser detector. I'll crawl back under my stone.