Gus, It was patented by 3M Safety and Security division as the "Opticom" system a long time ago. The detectors are the little black cylinders about 3" OD x 5" long with 1 or 2 snorkels coming out of them in a horizontal plane that sit on top of the stop lights around fire stations. They respond to two different frequencies of strobed infrared light pulse trains. One is for emergency vehicles and the other one is for alderman and other less important uses. Yes, I know the frequencies. No, I can't reveal them due to a non-disclosure agreement. It is a pretty slick system (in all modesty), and works up to 1/4 mile away. Edward Gisske, P.E. Gisske Engineering 608-523-1900 gisske@offex.com ----- Original Message ----- From: "Gus S.Calabrese" To: Sent: Monday, June 14, 2004 11:34 AM Subject: [OT]: detecting emergency vehicles > Hello Gurus > > I think that emergency vehicles are detected at > stoplights. Is there a standard way this is done > that can be adapted to a PIC ? > > Is emergency vehicle detection a patented process ? > Can anyone use it in a product ? > > Gus S Calabrese > 303.964.9670 vm 303.908.7716 cell no vm > www.omegadogs.com > 4337 Raleigh St > Denver, CO 80212 > > -- > http://www.piclist.com hint: To leave the PICList > mailto:piclist-unsubscribe-request@mitvma.mit.edu -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu