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Traffic Light Control For The Masses
uniformed1 writes "Eliminating red lights along the routes of their vehicles can give
emergency response teams the few extra critical minutes that can save
lives and property. A front page article
in today's Detroit News details
the emerging problem with a device that is now being made available to
the public -- a traffic light changer. Originally intended only
for emergency vehicles, the $300 MIRT (mobile infrared transmitter)
emits an infrared beam that signals traffic signals to turn green and
gives the vehicle the right-of-way. It is only a matter of time
before self-centered drivers start using the devices widely to skirt
traffic congestion, which is creating fears that chaos will
ensue." Maybe if everyone had these, it would lead to smarter intersections.
www.themirt.com has a lot of info on these devices. Even a dealer list of where to get one. Man, I'm tempted...
-mikey
In most cities, the light goes green for the guy with the transmitter, but a white strobe light on the same pole goes off too. If all lights went red, but the strobe still went off, the should be enough to make the driver confident that all directions are indeed red.
When information is power, privacy is freedom.
your average CCD will detect IR. Don't believe me? Pull out your camcorder and aim a remote at the camcorder. It looks like white light. I know where I live, we have CCD DOT cams at almost every intersection. It would be easy to pick out the car emitting the bright flashes.
I guess the slashdot editors editors weren't too into the hacking/phreaking scene back in the day. This was documented some 10 years ago.
If you want proof, consult the google time machine. Scroll down or search for "Chrome Box".
Here is some more information with pictures of the Optocom sensors (mounted to the signals) and of EMS and Fire transmission units.
I assume the old ones where nothing more than an infared flashlight, and the "upgraded" ones use some sort of modulation something like a TV remote. The picture in the article shows what looks like a 3rd brake light with a lighter plug. It probably costs $20. They're basically charging $300-$500 for a long range TV remote control
The traffic light control system itself is called Opticom . It is patented and manufactured by 3M.
It operates using very short pulses of light (< 10uS) occuring at a precise frequency (usually crystal controlled). The normal pulse rate is about 10Hz. An optional rate of around 12.5Hz can be used to give priority to other vehicles (ex. ambulance vs firetruck).
The system is configurable and normally set to give a green light to the emergency vehicle (helping to clear traffic) but it can also be set to go red in all directions.
Wouldn't work if it was done right.
I use an infrared remote to access my condo - it uses an infrared remote system that's fairly simple, yet effective:
-The remote (much like garage door openers) uses a rolling pseudo-random number sequence. The remote generates a code based on the next number in sequence from a random number generator seeded with a known key for that particular remote (the main controller needs to be "paired" with the remote before use so it knows what seed each remote is using).
-The controller keeps track of all of the remotes for the building and pre-computes the next 256 valid codes that each remote will generate based on the seed exchanged when the remote is paired.
When a remote triggers, it sends the random number code (NOT the key) by way of infrared to the controller receiver. The controller checks to see if the number the remote transmitted is in the next 256 valid numbers for that particular remote, if so, you get in. If not, you don't and the attempt is logged.
If you press the button more than 256 times (playing with the remote button for example) when you're not around the sensor, none of the precompute codes will match the next time the remote is used and it will be useless until re-paired.
Even if you capture the code being sent from the remote, you won't know the key that the random number generator is using in that particular remote to generate the number sequence, or any of the subsequent numbers that the remote would generate. You'd only capture the code that was sent, and once that was used, it wouldn't work again anyway.
If a remote key is compromised, it's simple to simply deactivate that particular remote key. If the system is brute-force attacked, it can either deactivate the sensor that's being attacked, or just call security to the appropriate location.
N.
"Nothing strengthens authority so much as silence." - Charles de Gaulle