LTI 20-20 UltraLyte 100 Calibration checks
Discussion
AA999 said:
Vaud said:
As I understand it the pulses are ~30ns. That is very brief. It sends 100-600 of these pulse at close to the speed of light. It completes calculations in 300-400ms - but it only needs a small sample - the car will not have moved an appreciable distance in that time.
https://en.wikipedia.org/wiki/LIDAR_speed_gun
"Laser pulse [Pulse A] "flies" towards the target and hits the target vehicle license plate. At the same time the pulse is released into flight [Release Time A], a timer is started by a high resolution high-speed timer built into the LiDAR gun. Additional laser pulses are also sent at a rate of 100-600 pulses per second. The advent of high-speed timers was a critical technology, making "time-in-flight" measurement of light possible. So the LiDAR measures time-in-flight of each pulse and requires only 2 pulses over a period of time of as little as 3 ms (theoretically) to determine the velocity of a vehicle. The LiDAR unit, however, takes additional measures in order to provide some additional validation that the measure is correct"
Just wondering what happens if for example during the pulses that 1/2 come back as a measurement from the wing mirror and the top part of bonnet and the second half as the gun traces down the bonnet and to the number plate?https://en.wikipedia.org/wiki/LIDAR_speed_gun
"Laser pulse [Pulse A] "flies" towards the target and hits the target vehicle license plate. At the same time the pulse is released into flight [Release Time A], a timer is started by a high resolution high-speed timer built into the LiDAR gun. Additional laser pulses are also sent at a rate of 100-600 pulses per second. The advent of high-speed timers was a critical technology, making "time-in-flight" measurement of light possible. So the LiDAR measures time-in-flight of each pulse and requires only 2 pulses over a period of time of as little as 3 ms (theoretically) to determine the velocity of a vehicle. The LiDAR unit, however, takes additional measures in order to provide some additional validation that the measure is correct"
Which set of results would it take and which would be rejected?
I guess it comes down to the word of the officer in him being confident that what he targetted was the exact same part of the vehicle along its track as it approached?
The return signal will not be a sharp pulse, it will be broader in the time domain than the original and vary in amplitude over that time. I do not know how complex the signal processing is on these units and it may be as simple as taking the peak amplitude time.
Alex said:
The offence was 67mph in a 60mph limit (A31 Hog's Back).
I pleaded not guilty, requested the calibration certificates, the video from the mobile speed camera. Surprisingly, they sent it all without question, although it took a few months.
I had it all reviewed by a speed camera "expert", who reckoned I had a case, but said I'd probably still lose in court.
At the first hearing, the police officer actually turned up. He was a really nice guy and even sat with me reviewing the video and explaining what he was doing at the time. He was due to retire in 2 weeks.
Another hearing was scheduled to hear the case. The day before I called to change my plea to guilty. Got 3 points and £165 fine.
So £65 (or £105) more than if you accepted the fine in the first place.I pleaded not guilty, requested the calibration certificates, the video from the mobile speed camera. Surprisingly, they sent it all without question, although it took a few months.
I had it all reviewed by a speed camera "expert", who reckoned I had a case, but said I'd probably still lose in court.
At the first hearing, the police officer actually turned up. He was a really nice guy and even sat with me reviewing the video and explaining what he was doing at the time. He was due to retire in 2 weeks.
Another hearing was scheduled to hear the case. The day before I called to change my plea to guilty. Got 3 points and £165 fine.
Had you nothing better to do?
HantsRat said:
Alex said:
The offence was 67mph in a 60mph limit (A31 Hog's Back).
Are you sure it was 67? ACPO charging guidelines start at 68. I was surprised, as was I expecting him to suggest 10% + 2. Or is he not qualified to say that, as he's not an officer?
Jacobyte said:
I received a NIP for 71mph on that same A31 Dual Carriageway stretch a few months ago. I was fortunate enough to be offered the naughty boy class run by AA DriveTech. During our educational session, one of my classmates asked the teacher what the lowest speed is for being zapped, to which the teacher said "there is no guideline, it could be just 1mph over".
I was surprised, as was I expecting him to suggest 10% + 2. Or is he not qualified to say that, as he's not an officer?
71 in a 70 or red ringed 60?I was surprised, as was I expecting him to suggest 10% + 2. Or is he not qualified to say that, as he's not an officer?
HantsRat said:
TOPTON said:
As you said, guidelines! and they are open to abuse. I was given 3 points for 67 on a 60
Not really abuse thought is it? 67 in a 60 is speeding. Me personally though would not be giving out tickets for anything under 70.So if they ignore this simple guideline/rule, what else do they twist to suit their own agenda
You're conflating guidelines with rules, for starters.
Furthermore, there's also this pertinent paragraph in the guidelines:
Also - playing Devils Advocate - what's on your speedo if you get caught at 67? Surely over 70?
Furthermore, there's also this pertinent paragraph in the guidelines:
Roads Policing Strategy 2011-15 said:
These guidelines do not and cannot replace police officer's discretion. Where an officer decides to issue a summons or a fixed penalty notice in respect of offences committed at speeds lower than those set out in the table, he or she must consider the tolerances of the equipment used to corroborate their opinion. Police speed equipment are tested and approved to work with a maximum tolerance of +/-2mph up to 66mph and 3% for all speeds higher than 66mph, so it is possible to use these tolerances as a prosecution threshold. Moreover, in particular circumstances, driving at speeds lower than the legal limit may result in prosecution for other offences, for example dangerous driving or driving without due care and attention when the speed is inappropriate and inherently unsafe.
I'd safely assume that if the equipment can ping you at a speed above the legal maximum for the road, and is above the tolerance, then it's possible you would be prosecuted.Also - playing Devils Advocate - what's on your speedo if you get caught at 67? Surely over 70?
Edited by Durzel on Tuesday 25th August 17:36
Durzel said:
You're conflating guidelines with rules, for starters.
Also - playing Devils Advocate - what's on your speedo if you get caught at 67? Surely over 70?
I'm not conflating anything, I know the difference but it seems the operators don't. Why have guidelines if they are not there to follow, unless some other situation happens to alter them. Also - playing Devils Advocate - what's on your speedo if you get caught at 67? Surely over 70?
Edited by Durzel on Tuesday 25th August 17:36
The one I met told me that his stupidly positioned vehicle is fine to be there as the only danger is the people speeding. [As the guidelines say they don't have to be in a legally parked position to carry out their duty}
Also playing devils advocate-----Why does everyone, like yourself, always assume speedometers over read by a large margin. Just because manufacturers guidelines say they may over read by up to 10%
Mine is 1mph out at 70
TOPTON said:
I know the difference but it seems the operators don't. Why have guidelines if they are not there to follow, unless some other situation happens to alter them.
I think you will find the vast majority of cases are within the guidelines. Put a FOI in to your local force asking how many people have had action taken against them under 35mph in a 30 zone. 
HantsRat said:
TOPTON said:
I know the difference but it seems the operators don't. Why have guidelines if they are not there to follow, unless some other situation happens to alter them.
I think you will find the vast majority of cases are within the guidelines. Put a FOI in to your local force asking how many people have had action taken against them under 35mph in a 30 zone. tapereel said:
Steady-on HantsRat, you do realise that by doing this the legend will dissolve. I predict your suggestion is not taken up.
We shall see...Keep an eye on... https://www.whatdotheyknow.com/body/hampshire_poli...
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