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# How does this speed camera work?

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1. This is one of those Infra red cameras that dont flash when they have caught a car speeding. The lines in front of it are used to confirm you are speeding i believe?

Where is the focus point of the beam which decides if you are speeding or not. Is it further down the road or is it trained on these lines?

lets say the beam is trained further down the road and catches a car speeding. What if the driver slows down before crossing over these lines?

Thanks for any help
2. I would assume that the speed camera flashes pulses of IR light and measures the time taken for the light to return/ bounce back. Then by doing some maths you will be able to find out how fast a car is moving. Then that triggers the camera to take a photo, if no conventional flash is used, an IR Flash can be used also because cameras pick up a wider range of wavelengths than the human eye, including IR light. Use your phone camera and point it at the LED of a tv remote and press some buttons and you will see the LED flash.

I would assume the road markings are used to identify the camera that took the photo (note the number 744). Some cameras will use them to give a scale of distance, if two photos are taken with a known pause between them, by comparing how far the car has traveled in between the two photos you can confirm that the car was speeding.
3. (Original post by Jonsmith98)
I would assume that the speed camera flashes pulses of IR light and measures the time taken for the light to return/ bounce back. Then by doing some maths you will be able to find out how fast a car is moving. Then that triggers the camera to take a photo, if no conventional flash is used, an IR Flash can be used also because cameras pick up a wider range of wavelengths than the human eye, including IR light. Use your phone camera and point it at the LED of a tv remote and press some buttons and you will see the LED flash.

I would assume the road markings are used to identify the camera that took the photo (note the number 744). Some cameras will use them to give a scale of distance, if two photos are taken with a known pause between them, by comparing how far the car has traveled in between the two photos you can confirm that the car was speeding.
I'll have to try that IR trick with the tv remote

From what you have said it sounds like the point where you are caught speeding/or not is when the car is over the lines?
4. I would assume the process happens like this:

Step 1: use either radar or IR laser's to identify the cars speed
Step 2: Take first photograph of car
Step 3: Wait for a few tenths of a second or so
Step 5: At this point I would assume the car has just passed over the line
Step 6: Take second photo
Step 7: Ruin some drivers day with a letter in the post
5. I have I identified the specific camera in use and this website should give you some more information, turns out that sensors embedded in the road are used instead of radar or lazer.
http://www.speedcamerasuk.com/truvelo.htm
6. (Original post by Jonsmith98)
I have I identified the specific camera in use and this website should give you some more information, turns out that sensors embedded in the road are used instead of radar or lazer.
http://www.speedcamerasuk.com/truvelo.htm
Thanks for all your help. I've been researching these truvelo cameras. All my life I thought the IR beam was used to bounce back from the vehicle and as you said earlier, relay the time it takes to return in order to determine the speed.

If that was the case then these cameras would be able to work for quite large ranges so it would be likely that it would have caught you before you see it. However this is not the case.

I had a look back on the original image and I found the sensors in the road which were cropped out of the image above.

So these cameras work with more or less the same ranges as the more common Gatso cameras just that they are front facing and use IR instead of visible light so the flash does not blind you.

Thanks again!
7. (Original post by Bern Herkins)

So these cameras work with more or less the same ranges as the more common Gatso cameras just that they are front facing and use IR instead of visible light so the flash does not blind you.

Yes.

The only IR part about a Truvelo is the flash to illuminate the picture. It's not related to speed.

They only have an IR flash because they are front facing, in order to photograph the driver.

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