Those frequencies are extremely easy to find and iirc both are in the double digits. Edward Gisske wrote: > 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 -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu