Excerpts from internet.cypherpunks: 18-Mar-94 Re: spyproofing your house/.. by Arsen Ray Arachelian@pri > <<Except that they would go off whenever the sun was up, or whenever a car > with its headlights on drives up.>> > > So is there a way to detect the specific IR that the bad guys use? Measure the ratio of IR to visible light.