Maybe nabbed with an LTI 20-20 by a T5
Discussion
Middle of the night, on a virtually deserted stretch of four lane motorway last night and I was shot at by a fully marked T5 with an LTI 20-20.
I was emerging from the cover of an artic at about (best not say, but less than the ton
) and I think I spotted him immediately. Braked down to 70 in 2-3 seconds and thought that's ok then. Then I saw the LTI!!!
For the BiBs, are they likely to put every catch through, or are you just looking for people going at warp speed? He didn't bother to follow me. I seemed to be the only driver who spotted him and braked.
How long does the LTI need to be locked on. Is a spot speed ok as I was breaking firmly all the time I was in view until I was at an indicated 70.
In the old days it seemed to be that if you spotted BiB, you were paying adequate attention and allowed to progress. Not so sure that will be the case now.
I was emerging from the cover of an artic at about (best not say, but less than the ton
) and I think I spotted him immediately. Braked down to 70 in 2-3 seconds and thought that's ok then. Then I saw the LTI!!! For the BiBs, are they likely to put every catch through, or are you just looking for people going at warp speed? He didn't bother to follow me. I seemed to be the only driver who spotted him and braked.
How long does the LTI need to be locked on. Is a spot speed ok as I was breaking firmly all the time I was in view until I was at an indicated 70.
In the old days it seemed to be that if you spotted BiB, you were paying adequate attention and allowed to progress. Not so sure that will be the case now.
0.3 seconds aquisition time, bounced off the highly reflective 'corner cube' or 'reflex reflector' on the backing of your number plate. (bounces light back in the direction that it came, in this case the infra red pulses)
LTI 2020 has to get 30 consistant reflections back. It neasures consistancy by effectively plotting the time of flight against time, and using a 'least squares' algorithm to establish the gradient, which is directly related to speed. However, if you're decelerating, then you can't plot a straight line, and you can't get the least squares algorithm to achieve a definitive result. The bottom line is, if your speed changes by more than 2 MPH in 0.3 seconds, the LTI throws it out. So that's about 7MPH seconds every second. I think you lose speed much quicker than that when you slam on.
have fun!
LTI 2020 has to get 30 consistant reflections back. It neasures consistancy by effectively plotting the time of flight against time, and using a 'least squares' algorithm to establish the gradient, which is directly related to speed. However, if you're decelerating, then you can't plot a straight line, and you can't get the least squares algorithm to achieve a definitive result. The bottom line is, if your speed changes by more than 2 MPH in 0.3 seconds, the LTI throws it out. So that's about 7MPH seconds every second. I think you lose speed much quicker than that when you slam on.
have fun!
bryan35 said:
0.3 seconds aquisition time, bounced off the highly reflective 'corner cube' or 'reflex reflector' on the backing of your number plate. (bounces light back in the direction that it came, in this case the infra red pulses)
LTI 2020 has to get 30 consistant reflections back. It neasures consistancy by effectively plotting the time of flight against time, and using a 'least squares' algorithm to establish the gradient, which is directly related to speed. However, if you're decelerating, then you can't plot a straight line, and you can't get the least squares algorithm to achieve a definitive result. The bottom line is, if your speed changes by more than 2 MPH in 0.3 seconds, the LTI throws it out. So that's about 7MPH seconds every second. I think you lose speed much quicker than that when you slam on.
have fun!
This is very interesting. Does that mean that if a number plate is tilted forwards, the beam is reflected to the road surface rather than back to the gun?
Also, is the error message received under the conditions you describe the same as the error message caused by a laser jammer?
nope chaps,
a 'reflex reflector' or 'corner cube mirror' as it is more correctly known as, replects light back in the direction in which it came. You can try it yourself using just 2 mirrors at 90 degrees to each other. No matter what angle you face them, you always see yourself. Quite handy on road signs, as you see them very brightly and most other road users don't (unless they are in the same line of sight)
tilted your number plate therefore makes no difference at all.
You can however asked the kind numberplate makers to sandwich in a sheet of IR opaque screen, which won't reflect IR at all, thus giving the LTI2020 a bit more of a hard time. Your headlights still relect however, though not nearly as well as the numberplate does.
a 'reflex reflector' or 'corner cube mirror' as it is more correctly known as, replects light back in the direction in which it came. You can try it yourself using just 2 mirrors at 90 degrees to each other. No matter what angle you face them, you always see yourself. Quite handy on road signs, as you see them very brightly and most other road users don't (unless they are in the same line of sight)
tilted your number plate therefore makes no difference at all.
You can however asked the kind numberplate makers to sandwich in a sheet of IR opaque screen, which won't reflect IR at all, thus giving the LTI2020 a bit more of a hard time. Your headlights still relect however, though not nearly as well as the numberplate does.
bryan35 said:
You can however asked the kind numberplate makers to sandwich in a sheet of IR opaque screen, which won't reflect IR at all, thus giving the LTI2020 a bit more of a hard time. Your headlights still relect however, though not nearly as well as the numberplate does.
So were would one get such plates from then? And are they visible to the human eye? not really.
I'm friends with the chap who was on the project team installing and testing the congestion charge cameras in London. They see in infra red, and saw only a grey plate when this film was used. In normal vision, the plate looks completely ordinary.
I'll have a look to check where the film can be bought from.
It's nothing too impressive to be honest.
Some video cameras have these filters on to avoid IR pick up. The police ones certainly do, otherwise on your video clip you'd see beating/strobing speculars and glare from the plate as the laser hits it.
I'm friends with the chap who was on the project team installing and testing the congestion charge cameras in London. They see in infra red, and saw only a grey plate when this film was used. In normal vision, the plate looks completely ordinary.
I'll have a look to check where the film can be bought from.
It's nothing too impressive to be honest.
Some video cameras have these filters on to avoid IR pick up. The police ones certainly do, otherwise on your video clip you'd see beating/strobing speculars and glare from the plate as the laser hits it.
Suprised that a LTI was being used by a T5...
Was is pointing out of the back?
If it was being held by the driver/passenger, it's more than likely to be a pro-laser...(however, you seem sure it's an LTI}
If he's pressed the button, the image and the speed will be recorded and he won't have any choice about whether it's processed or not...
The LTI obviously captures the image and so 'coming after you' isn't required. Where the pro-laser requires the BiB to actually stop the driver. I presume you already know that though
Was is pointing out of the back?
If it was being held by the driver/passenger, it's more than likely to be a pro-laser...(however, you seem sure it's an LTI}
If he's pressed the button, the image and the speed will be recorded and he won't have any choice about whether it's processed or not...
The LTI obviously captures the image and so 'coming after you' isn't required. Where the pro-laser requires the BiB to actually stop the driver. I presume you already know that though
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