Stoplights

[RFI-EMI-GUY]

Gottagetmeone!

 

[prcguy]

There are two very specific crystal controlled rep rates used in the 3M Opticom, one for busses and non emergency vehicles and the other for emergency vehicles. The non emergency strobes have an IR filter on the strobe light so as not to affect other drivers and the emergency strobe is blinding. The non emergency strobe is like pushing the cross walk button at an intersection and it goes through the normal countdown cycle where the emergency version immediately turns the opposing direction yellow then red. I had the emergency rep rate strobe with an IR filter. Works very well.

That is called opticom, a repetitive pulse (strobe) of light. each strobe has a strobe like a coded light signal that compares to remote control. Sad part is because people were using home made strobes for this, cities have changed the lights to 4 way red. Want to make one, the flash from a camera works well. All sorts of DIY strobe circuits online.
Yea, get caught preemting a traffic signal you loose your goodies at minimum, some cities may have fines over that.

 

[captaincab]

Now if only we could get more people to get out of the way when an emergency vehicle comes down the road with lights flashing! (It's amazing what people forget once they pass diver's ed.)

A reason why my old department ran a dual tone siren plus train horns and a Federal Q siren. No one could say they didn’t hear us with a power call a Q and them horns.

 

[WB9YBM]

A reason why my old department ran a dual tone siren plus train horns and a Federal Q siren. No one could say they didn’t hear us with a power call a Q and them horns.

..and with sound-proofing in cars improving over the decades (to get rid of road and/or engine noise, I guess) those sirens (I'll wager) have needed to get louder; that's also why, I've been told, they've also had to increase the amount of blinky-lights on emergency vehicles. (Although the way some people crank their car stereos I'm surprised anyone can hear much of anything anyway.)

 

[redbeard]

I used to have a Tomar unit that matched the Opticom pattern. It was hooked to a standard Whelen hideaway curly-q strobe bulb hidden in the front amber turn signal on my Jeep.

One thing to keep in mind is that most of those systems have an activation confirmation lamp hanging up with the traffic lights. Usually a white incandescent spotlight bulb that lights up when your preemption signal is received. Dead giveaway someone is using preemption and visable for some distance. You won't sneak through unnoticed by those who notice.

 

[PrivatelyJeff]

(Although the way some people crank their car stereos I'm surprised anyone can hear much of anything anyway.)

I came up with an idea a few years ago that used an FM directional transmitter that you mount to the front of an emergency vehicle that would cause an override of the cars stereo system and allow the emergency vehicle to alert the car to pull over.

 

[tweiss3]

There are many different preemption types. Depending on the locality and funding, we use Audio (directional horn picks up siren), IR (opticom and similar) and GPS based (uses GPS, vehicle telematics and 2.4GHz to talk to the signal systems).

 

[kg4pbd]

Back in the 60's in Erie, PA, a system was put in place called Rad O Lite, or RELCO. There was a small box in each emergency vehicle with a toggle switch labeled "N/S" and "E/W". A uhf transmitter in the car sent a signal to a receiver at each traffic light which turned the light green and activated a flashing white light to warn motorists. It wasn't perfect, and I think it has pretty much been abandoned. Not sure as I haven't live there in 35 years. Here is an interesting read on the system:

Rad-O-Lite RELCO Emergency Lights

Old Time Erie - 1971 ad for RELCO. Remember the white light at the top of the traffic lights in Erie, PA that would blink when triggered...

oldtimeerie.blogspot.com

 

[WB9YBM]

I came up with an idea a few years ago that used an FM directional transmitter that you mount to the front of an emergency vehicle that would cause an override of the cars stereo system and allow the emergency vehicle to alert the car to pull over.

Interesting idea, although if someone's going to ignore lights flashing in their face (and/or mirror) they'll probably ignore their radios too. After having heard hackers getting into vehicle computer systems and activating their brakes and/or corrective steering functions, I think something like that (on a more "official" use) would be more effective in getting cars out of the way. Like maybe putting strobe light detectors on cars to activate on-board program in the cars' computer to get it to pull over.

 

[PrivatelyJeff]

Interesting idea, although if someone's going to ignore lights flashing in their face (and/or mirror) they'll probably ignore their radios too. After having heard hackers getting into vehicle computer systems and activating their brakes and/or corrective steering functions, I think something like that (on a more "official" use) would be more effective in getting cars out of the way. Like maybe putting strobe light detectors on cars to activate on-board program in the cars' computer to get it to pull over.

Sometimes it’s ignoring and other times you just don’t see/hear them until it’s too late and it’s hard to pull over. Plus my idea is simple and also something that can be retrofitted into cars when they get new car stereos. The stereos would always monitor the dedicated FM frequency for a sub-audible tone and when it receives it, it would trigger the radio to switch to that source (and turn on if off), at a fixed volume. In more integrated radios, it could even display a message on the dash and tell you to pull over.

 

[chief21]

I came up with an idea a few years ago that used an FM directional transmitter that you mount to the front of an emergency vehicle that would cause an override of the cars stereo system and allow the emergency vehicle to alert the car to pull over.

Back around the late 90's or so, there was a system that alerted vehicles through radar detectors. The agency I worked for had several of them installed as a test of concept. Certain radar detectors advertised the technology as the Safety Warning System, or SWS.

Here is a related excerpt from the Chicago Tribune in 1996...

The system, developed by Chicago-based Cobra Electronics Corp., works this way: High-speed emergency vehicles, such as squad cars and ambulances, are equipped with a transmitter. When the emergency lights are switched on, the transmitter sends out a special radar signal that activates every radar detector within a one-mile radius.
The idea is to make motorists aware of an approaching emergency vehicle so drivers can slow down or yield the right of way. The company also has introduced a new detector that can differentiate between traditional radar signals and the signals sent from transmitters.
In the case of transmitter signals, the words "Emergency Vehicle" appear on the detector's digital display. The words "Road Hazard" appear on the display when the vehicles stop and park.

 

[PrivatelyJeff]

Back around the late 90's or so, there was a system that alerted vehicles through radar detectors. The agency I worked for had several of them installed as a test of concept. Certain radar detectors advertised the technology as the Safety Warning System, or SWS.

Here is a related excerpt from the Chicago Tribune in 1996...

The system, developed by Chicago-based Cobra Electronics Corp., works this way: High-speed emergency vehicles, such as squad cars and ambulances, are equipped with a transmitter. When the emergency lights are switched on, the transmitter sends out a special radar signal that activates every radar detector within a one-mile radius.
The idea is to make motorists aware of an approaching emergency vehicle so drivers can slow down or yield the right of way. The company also has introduced a new detector that can differentiate between traditional radar signals and the signals sent from transmitters.
In the case of transmitter signals, the words "Emergency Vehicle" appear on the detector's digital display. The words "Road Hazard" appear on the display when the vehicles stop and park.

I think I saw something like that. Interesting.

 

[WB9YBM]

When the emergency lights are switched on, the transmitter sends out a special radar signal that activates every radar detector within a one-mile radius.

Especially in a big city, there's a lot of stuff within a one mile radius that's going to block RADAR signals--everything from vehicles to buildings (unless they plan on blasting through that with some kind of high-power set-up). I wonder how they'd address that issue?

 

[chief21]

Especially in a big city, there's a lot of stuff within a one mile radius that's going to block RADAR signals--everything from vehicles to buildings (unless they plan on blasting through that with some kind of high-power set-up). I wonder how they'd address that issue?

In actual practice, we didn't really care about the range anywhere except immediately ahead of the emergency vehicle (and a bit to either side for intersections). In fact, we found that the antenna used for the radar transmitter tended to be somewhat directional to the front of the vehicle. I suppose that the "one-mile radius" specification was probably more related to the scenario where the vehicle was parked on the side of the roadway at an incident.

 

[Tech21]

This is kind of radio related. What frequency do the devices that change the traffic lights green for emergency vehicles?. With software radios I would think one could build one with the correct frequency and change the lights. It's a fascinating system and it would be nice to be able to change the light especially when stuck in traffic. Is there a tone or DTMF that's transmitted to switch them or is it some super secret technology.

MIRT's are illegal to own and do come with a minimum 6 months in prison if caught and eventually you will be caught. Traffic lights with the sensor for emergency vehicles are networked and monitored. If that sensor is tripped without an emergency vehicle activating it, it will be known.

 

[west-pac]

Sometimes it’s ignoring and other times you just don’t see/hear them until it’s too late and it’s hard to pull over. Plus my idea is simple and also something that can be retrofitted into cars when they get new car stereos. The stereos would always monitor the dedicated FM frequency for a sub-audible tone and when it receives it, it would trigger the radio to switch to that source (and turn on if off), at a fixed volume. In more integrated radios, it could even display a message on the dash and tell you to pull over.

If you're going to do that you might as well have them listen to the strongest NOAA Weather Radio frequency as well.

 

[KK4JUG]

Gee whiz, guys. If you begin using anything to stop cars at an intersection, then you drive through, don't you think somebody's gonna notice? I don't see the benefit of putting it in a private vehicle.

 

[PrivatelyJeff]

If you're going to do that you might as well have them listen to the strongest NOAA Weather Radio frequency as well.

Possibly but in some areas they can have multiple strong signals or in the case of some coastal areas, they have two, one for local weather and one for ocean forecast.

 

[PrivatelyJeff]

Gee whiz, guys. If you begin using anything to stop cars at an intersection, then you drive through, don't you think somebody's gonna notice? I don't see the benefit of putting it in a private vehicle.

They generally only stop cross traffic, and give a green light to whatever direction you’re driving (at least the systems I’ve seen).

 

[prcguy]

Rules and laws against using them, of course. 6mo in prison, no. Especially where I live, the guy who broke into your car or house is released in an hour and they let murders out early because of crowded prisons and COVID.

Anyone trying to find my friends using Opticom transmitters would need an IR camera just to start looking for them. I still have some Opticom equipment but I haven't used it in years because there is no Opticom traffic lights where I usually drive.

MIRT's are illegal to own and do come with a minimum 6 months in prison if caught and eventually you will be caught. Traffic lights with the sensor for emergency vehicles are networked and monitored. If that sensor is tripped without an emergency vehicle activating it, it will be known.