PIC Project, Special Input

[cpt591]

Hello, I am using a PIC to control a traffic management system. I am using IR circuits to detect when cars are present. However, I need a way to recognize when emergency vehicles are present so they will get priority. Any ideas?? Thanks.

[L. Daniel Rosa]

Look for a specific strobe pattern.

[Mike]

I don't know about where you live but here they have bright flashers on the traffic lights that go on whenever the ambulances go through with their sirens on. Plus, it changes the light immediately to give them the green light.<p>Maybe you could use some sort of RF systems, or since you are using IR detectors maybe you can have the ambulances have some sort of IR lights that flash a certain code for the sensors on the PIC circuit to activate the lights in their favor.

[philba]

look up MIRT. Its a standard infared transmitter used by emergency vehicles.

[asm_2750]

I would use an IR detector, and have an IR emitter on the emergency car emit in a certian pattern, when the detector notices this, it halts all traffic, and quickly gives the emergency car priorty.<p>What ive herd is that traffic signals have certian light detectors that look for a certian frequency of light, that is emited by a ambulance and such, however i dont know if thats true or not. One thing that might be really true is that, emergency services probably have access to the traffic system directly, and just give right away, but that would only work is the entire traffic system was networked which is possiblely true.

[philba]

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by asm_2750:
I would use an IR detector, and have an IR emitter on the emergency car emit in a certian pattern, when the detector notices this, it halts all traffic, and quickly gives the emergency car priorty.<p>What ive herd is that traffic signals have certian light detectors that look for a certian frequency of light, that is emited by a ambulance and such, however i dont know if thats true or not. One thing that might be really true is that, emergency services probably have access to the traffic system directly, and just give right away, but that would only work is the entire traffic system was networked which is possiblely true.<hr></blockquote><p>Sigh... Yes, the transmitter on emergency vehicles is called MIRT. just like I said. Typically, only busy intersections have them. MIRT = Mobile InfraRed Transmitter. <p>You can even built a MIRT device but it is illegal to use (and in some places even possess).<p>google and ye shall receive...

[Gary]

One of these days the automatic cameras that take pictures of red light runners will do the same for cars pretending they are emergency vehicles. If they don't do that already.

[philba]

I have read of several municipalities that claim they do exactly that. Also, a video or still camera will show up an IR blaster on a car so it will be quite obvious. <p>On the other hand, for a system so short sighted as to not have any security built in, I kind of doubt they thought that one through at all. Still, anyone who uses a MIRT is running a huge risk to gain such a small benefit.