This is just a guess, but here goes... Infrared radiation is all around us. People "glow" in the infrared and room temperature objects also emit some IR radiation.
Generally, that background IR signature is constant (chairs don't move around) or only slowly changing with time (people walk by slowly). But if a device's IR output signal is modulated at, say 95 kHz, it can easily be picked out from the background. That signal can then be pulse-modulated (analogous to Morse code) to send desired commands. Jim On Wednesday 25 May 2005 21:47, Pierre Abbat wrote: > On Wednesday 25 May 2005 20:11, Bill Hooper wrote: > > Are they just way off on their figures, or is there something here that > > I don't understand? Could the 95 kHz be a frequency at which the much > > higher frequency infra-red waves are modulated or something? Anybody > > have any ideas on this? > > The 95 kHz signal is a carrier which is modulated with data, and the > infrared is modulated with that. It's been a few years since I worked on > data radio designs and heard of this, so I don't remember how it's > modulated. > > phma -- James R. Frysinger Lifetime Certified Advanced Metrication Specialist Senior Member, IEEE http://www.cofc.edu/~frysingj [EMAIL PROTECTED] [EMAIL PROTECTED] Office: Physics Lab Manager, Lecturer Dept. of Physics and Astronomy University/College of Charleston 66 George Street Charleston, SC 29424 843.953.7644 (phone) 843.953.4824 (FAX) Home: 10 Captiva Row Charleston, SC 29407 843.225.0805
