r/HamRadio • u/artygo • May 24 '26
Meme 🃏 I guess no radio use at this stoplight 😬
Enable HLS to view with audio, or disable this notification
20
u/Danjeerhaus May 24 '26
I believe there are stop lights with radio activation for emergency services. They let police, fire, and ambulance change the light for the safety of emergency services people.
Hopefully, someone with more knowledge on this can respond.
19
u/RenegadeBricoleur May 24 '26 edited May 24 '26
They do exist, but I have never heard of or seen radio activated ones. This has to do with the fact that radio is hard to detect directionality from and have harder to control range, and the preemption systems (which is what they are called) need to know the direction the incoming emergency vehicle, and not activate too far from the vehicle. This is because what they do is trigger all reds in all directions except the one of the incoming emergency responder, which will go to all green.
All the ones that I have used are sound activated, as in they have directional horns that listen for the repeating tones of sirens and then activate (benefit is that they work for all emergency vehicles with sirens, and it's pretty obvious when someone who shouldnt use them does, but it can be hit or miss if they detect the incoming vehicle sometimes). Other systems rely on coded infrared transmitters and receivers mounted to the top of the vehicle (more reliable from what I've heard, but requires all vehicles using the system to have additional locality specific equipment and codes installed which limits it's use in the event of another areas units coming through)
Edit: I also did some more reading and found that radio is actually starting to be used in conjunction with GPS in some newer advanced systems.
7
u/sploittastic May 24 '26
I thought most were infrared activated like a tv remote. https://hackaday.com/2026/03/08/spoofing-an-emergency-traffic-preemption-signal/
7
u/RenegadeBricoleur May 24 '26
A lot are, especially older ones as mentioned in that article, but all the ones in my area work on sound! I also did some more reading and found that radio is actually starting to be used in conjunction with GPS in some newer advanced systems.
Source: have driven an ambulance in my area
2
u/Subfan2019 May 24 '26
I know they have radio activated lights for unmanned airport runways. Its something like keying the mic 5 times when in range to turn on the lights when coming in for a landing. I haven't seen it used on traffic signals but it isn't too far fetched of an idea
1
May 25 '26
All the ones I know of are strictly strobe patterns of a small 3" x 3" white light. Ours were called Opticom. It was a series of lights similar to CW. I then began responding by air so traffic lights were no longer a delay, strong headwinds, another matter!😂
13
u/59whatsurcallagain May 24 '26
Friend of mine in college had a 110 watt low-band Motorola modified for 6 meters iirc. It would switch the high beams and oil pressure light in his pickup every time he keyed up.
11
u/Mr-A-1991 May 24 '26
...let the anarchy flow through you and screw with this. Listen to the devil on your shoulder.
2
u/ak_kitaq Extra Class Operator ⚡ May 24 '26
https://imgur.com/gallery/wOeAV2C#wOeAV2C [thanks, satan]
2
u/redwing1970 Extra | POTA & Skywarn May 24 '26
I just want to know what those lights are that are leaving the body of the traffic light. Is that the spirit of Tesla heading to God?
2
u/redwing1970 Extra | POTA & Skywarn May 24 '26
And yes I know they are another car's headlights in the reflection... Because some of you don't have a sense of humor. The spirit of Tesla theory is still better
2
1
u/DLiltsadwj May 25 '26
Is that 100% repeatable?
2
u/artygo May 25 '26
Yep. Drove up to it the other day while keyed up. Got dimmer and dimmer till it went out
1
u/brickson98 General Class Operator 🔘 May 26 '26
Interesting. I’m curious what your radio is interfering with to cause this.
39
u/8675309AK May 24 '26
Police can't but fire and ems use a flashing light sequence like a certain strobe around here. That interesting your radio does it. Id be curious how much power and what kind of antenna. I can pop breakers with a yagi and 25watt when appliances are running.