Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!swrinde!cs.utexas.edu!sun-barr!newstop!texsun!letni!rwsys!kf5iw!k5qwb!lrk From: lrk@k5qwb.lonestar.org (Lyn R. Kennedy) Newsgroups: sci.electronics Subject: Re: IR receiver on traffic lights ? Message-ID: Date: 12 Apr 91 17:26:24 GMT References: <1991Apr11.211957.7309@lynx.CS.ORST.EDU> Organization: Radio Amateur k5qwb Lines: 26 youngqd@jacobs.cs.orst.edu (Dean Youngquist) writes: > The fire trucks in my town seem to trip traffic lights to green in > their direction as they are approaching the intersection. Does anyone > know how they do this? I thought they might have a system using > infra-red light ? If it is infra-red how can they work in the day-time? > Doesn't the sun put out infra-red that would interfere ? > > Dean Youngquist youngqd@jacobs.cs.orst.edu > Corvallis, Oregon 97330 Tel. (503) 757-0335 One system that works uses a strobe light on the vehicle. This can be easily seen among the other lights. The traffic signal also has a detector up near the middle of the intersection for each direction. I've heard Dallas is experimenting with a system that uses radio in the 800 Mhz range but it's small scale and on the other side of town so I haven't had much time to check it out. ------------------------------------------------------------------------- lrk@k5qwb.lonestar.org lrk@k5qwb.UUCP 73, utacfd.utarl.edu!letni!rwsys!kf5iw!k5qwb!lrk Lyn Kennedy K5QWB @ N5LDD.#NTX.TX.US.NA P.O. Box 5133, Ovilla, TX, USA 75154 -------- "We have met the enemy and they are us." Pogo -----------------