Help - Search - Members - Calendar
Full Version: A Review Of Laser Speed Meters
FightBack Forums > Queries > Technical Discussion of Enforcement Devices
Pages: 1, 2
Jlc
QUOTE (Yvan Dutil @ Thu, 21 Jan 2016 - 15:50) *
By the way, does anyone in tried to used the video as an alternate speed measure? This should by a straight forward prima facie proof.

Video, using points of reference with a simple time over distance measurement could be employed - either by the defence or prosecution. However, the person doing this would have to meet certain criteria to be considered an 'expert witness'. But bear in mind such a measurement would be a mean and not an 'instantaneous' measurement like the laser.
Jlc
This link is worth a read.

This thread has some interesting nuggets.
Yvan Dutil
QUOTE (Jlc @ Thu, 21 Jan 2016 - 12:03) *
QUOTE (Yvan Dutil @ Thu, 21 Jan 2016 - 15:50) *
By the way, does anyone in tried to used the video as an alternate speed measure? This should by a straight forward prima facie proof.

Video, using points of reference with a simple time over distance measurement could be employed - either by the defence or prosecution. However, the person doing this would have to meet certain criteria to be considered an 'expert witness'. But bear in mind such a measurement would be a mean and not an 'instantaneous' measurement like the laser.


Well, there is open source video analysis software used for physics teaching that can provide frame by frame speed estimate.
peterguk
QUOTE (Yvan Dutil @ Wed, 20 Jan 2016 - 21:10) *
I am consulting on a case using a Ultralte LTI LR100.


Out of interest, is this a speeding case? If so, what was the alleged speed and limit?
Yvan Dutil
QUOTE (peterguk @ Thu, 21 Jan 2016 - 15:31) *
QUOTE (Yvan Dutil @ Wed, 20 Jan 2016 - 21:10) *
I am consulting on a case using a Ultralte LTI LR100.


Out of interest, is this a speeding case? If so, what was the alleged speed and limit?


179 km/h in a 100 km/h zone. Clocked at 262 m and it is a motorcycle. The police dis a very large sweep to catch the motorcycle. The target is small, far and there is a large sweep. Everything is place for a slip error.
Jlc
...and the rider is alleged they weren't exceeding 100km/h?
Yvan Dutil
QUOTE (Jlc @ Thu, 21 Jan 2016 - 17:06) *
...and the rider is alleged they weren't exceeding 100km/h?


About that! There was two motorcycles. He claim that he has seen the police officer and slowed down while the other guy escaped. There was actually another moto that has escaped. The guy seams honest ans a confusion is possible but this is hard to demonstrate. It might be a lidar failure also. Anyway, legal contestation of speeding ticket is disappearing in Quebec. There is roughly 20 cases per year for over 600 000 tickets and roughly 1700 extreme speeding. Ticket number have been cut by a factor 3 in 5 years due to an increase repression. Probability of winning is roughly 10%. Just to say, I am not making a living from this.
Jlc
QUOTE (Yvan Dutil @ Thu, 21 Jan 2016 - 21:32) *
He claim that he has seen the police officer and slowed down while the other guy escaped.

As you know the speed measurement is usually made by the time the officer was spotted and deceleration occurred... Although I agree a bike is a harder target with a very different profile to a car.
Yvan Dutil
QUOTE (Jlc @ Fri, 22 Jan 2016 - 05:24) *
QUOTE (Yvan Dutil @ Thu, 21 Jan 2016 - 21:32) *
He claim that he has seen the police officer and slowed down while the other guy escaped.

As you know the speed measurement is usually made by the time the officer was spotted and deceleration occurred... Although I agree a bike is a harder target with a very different profile to a car.


Well, in that specific case my client said he had seen the police officer when he was nearing him. The police officer has taken is measurement when I was moving away. It was the noise of the motorcycle that has attracted is attention as he was doing some radar in the opposite direction. This is why there is a large sweep and that the pointing might now have been as stable as in a normal situation.

Off course, nothing is black and white. Nevertheless, I never take a case when I don't think it might have a technical issue involved. Also, my client are warned from the beginning that the physics is useless if they lied.
CL22
QUOTE (Yvan Dutil @ Fri, 22 Jan 2016 - 14:52) *
QUOTE (Jlc @ Fri, 22 Jan 2016 - 05:24) *
QUOTE (Yvan Dutil @ Thu, 21 Jan 2016 - 21:32) *
He claim that he has seen the police officer and slowed down while the other guy escaped.

As you know the speed measurement is usually made by the time the officer was spotted and deceleration occurred... Although I agree a bike is a harder target with a very different profile to a car.


Well, in that specific case my client said he had seen the police officer when he was nearing him. The police officer has taken is measurement when I was moving away. It was the noise of the motorcycle that has attracted is attention as he was doing some radar in the opposite direction. This is why there is a large sweep and that the pointing might now have been as stable as in a normal situation.

Off course, nothing is black and white. Nevertheless, I never take a case when I don't think it might have a technical issue involved. Also, my client are warned from the beginning that the physics is useless if they lied.

I think the pysics will be useless if the physicist is confused about the technologies involved. Is it radar or laser?

If you don't already know anything about the laser device, it is clear you know very little about it, the court is unlikely to consider you an expert in these devices. You may be encouraged to know that the court will at least listen to you but do not be too surprised if they discard your evidence. They are likley to do that if you reference some handy and free garbage you picked up online.

An expert witness for a laser speed gun will be aware of how it manages the physics before that witness examines and comments on the case. Even someone who has a very good knowledge of physics is unlikely to be an expert in laser speed guns. Your questions about the physics involved shows your client is not being well served, indeed and expert witness trawling web forums for tuition in his expert subject, oh dear.
Yvan Dutil
QUOTE (CL22 @ Fri, 22 Jan 2016 - 13:38) *
QUOTE (Yvan Dutil @ Fri, 22 Jan 2016 - 14:52) *
QUOTE (Jlc @ Fri, 22 Jan 2016 - 05:24) *
QUOTE (Yvan Dutil @ Thu, 21 Jan 2016 - 21:32) *
He claim that he has seen the police officer and slowed down while the other guy escaped.

As you know the speed measurement is usually made by the time the officer was spotted and deceleration occurred... Although I agree a bike is a harder target with a very different profile to a car.


Well, in that specific case my client said he had seen the police officer when he was nearing him. The police officer has taken is measurement when I was moving away. It was the noise of the motorcycle that has attracted is attention as he was doing some radar in the opposite direction. This is why there is a large sweep and that the pointing might now have been as stable as in a normal situation.

Off course, nothing is black and white. Nevertheless, I never take a case when I don't think it might have a technical issue involved. Also, my client are warned from the beginning that the physics is useless if they lied.

I think the pysics will be useless if the physicist is confused about the technologies involved. Is it radar or laser?

If you don't already know anything about the laser device, it is clear you know very little about it, the court is unlikely to consider you an expert in these devices. You may be encouraged to know that the court will at least listen to you but do not be too surprised if they discard your evidence. They are likley to do that if you reference some handy and free garbage you picked up online.

An expert witness for a laser speed gun will be aware of how it manages the physics before that witness examines and comments on the case. Even someone who has a very good knowledge of physics is unlikely to be an expert in laser speed guns. Your questions about the physics involved shows your client is not being well served, indeed and expert witness trawling web forums for tuition in his expert subject, oh dear.


I have designed instrument for space mission. Hence, I understand pretty well how a lidar work. I have read the patents of LTI too. I have only two questions I cant find the information on it. One is related to the optics and I may solve this issue by buying an Ultralyte. The second is to get a description of the anti-slip algorithm. And this forum is the only place I have seen some substantiated information about it. Therefore, I am asking people here in order to be able to find a more primary source.

Also, you should be aware that people doing legal engineering are doing exactly the same thing I do. They are trolling forums, facebook accounts to gather information simply because most of the time there is no information published by the companies involved.

And the crown is already considering me as an expert, because they will bring their own expert at the next court audience. Hence, this issue is solved.
bama
you may have to buy (at least) one identical model with identical firmware and get 'into it' to get the algorithm.

(I ass-um-e its not same as in patent 5652651)
CL22
QUOTE (Yvan Dutil @ Fri, 22 Jan 2016 - 16:48) *
QUOTE (CL22 @ Fri, 22 Jan 2016 - 13:38) *
QUOTE (Yvan Dutil @ Fri, 22 Jan 2016 - 14:52) *
QUOTE (Jlc @ Fri, 22 Jan 2016 - 05:24) *
QUOTE (Yvan Dutil @ Thu, 21 Jan 2016 - 21:32) *
He claim that he has seen the police officer and slowed down while the other guy escaped.

As you know the speed measurement is usually made by the time the officer was spotted and deceleration occurred... Although I agree a bike is a harder target with a very different profile to a car.


Well, in that specific case my client said he had seen the police officer when he was nearing him. The police officer has taken is measurement when I was moving away. It was the noise of the motorcycle that has attracted is attention as he was doing some radar in the opposite direction. This is why there is a large sweep and that the pointing might now have been as stable as in a normal situation.

Off course, nothing is black and white. Nevertheless, I never take a case when I don't think it might have a technical issue involved. Also, my client are warned from the beginning that the physics is useless if they lied.

I think the pysics will be useless if the physicist is confused about the technologies involved. Is it radar or laser?

If you don't already know anything about the laser device, it is clear you know very little about it, the court is unlikely to consider you an expert in these devices. You may be encouraged to know that the court will at least listen to you but do not be too surprised if they discard your evidence. They are likley to do that if you reference some handy and free garbage you picked up online.

An expert witness for a laser speed gun will be aware of how it manages the physics before that witness examines and comments on the case. Even someone who has a very good knowledge of physics is unlikely to be an expert in laser speed guns. Your questions about the physics involved shows your client is not being well served, indeed and expert witness trawling web forums for tuition in his expert subject, oh dear.


I have designed instrument for space mission. Hence, I understand pretty well how a lidar work. I have read the patents of LTI too. I have only two questions I cant find the information on it. One is related to the optics and I may solve this issue by buying an Ultralyte. The second is to get a description of the anti-slip algorithm. And this forum is the only place I have seen some substantiated information about it. Therefore, I am asking people here in order to be able to find a more primary source.

Also, you should be aware that people doing legal engineering are doing exactly the same thing I do. They are trolling forums, facebook accounts to gather information simply because most of the time there is no information published by the companies involved.

And the crown is already considering me as an expert, because they will bring their own expert at the next court audience. Hence, this issue is solved.

You are not working on a space ship now
Good luck.
Perhaps post how you get on.
southpaw82
Oh look. Some criticism of laser speed meters is posted and all of a sudden a new member pops up to trash it. Never seen that before.
Yvan Dutil
QUOTE (CL22 @ Fri, 22 Jan 2016 - 15:14) *
You are not working on a space ship now
Good luck.
Perhaps post how you get on.


Laser speedometer is a simple technology. Radar speedometer also. Notwithstanding the fact that radar is not my field of expertise, I dit manage to find a non documented failure mode that was happening to apply to the specific case I was working on. So I am pretty confident I can manage to understand the inner working of the laser speedometer. The challenge however is to gather pertinent information. I have now, it is quote like «I remember I have read something about it». If I can just put my hand on the document I would be even with the seller or the tech guy who repair it.
notmeatloaf
QUOTE (Yvan Dutil @ Fri, 22 Jan 2016 - 17:48) *
The second is to get a description of the anti-slip algorithm.

Bit of a late reply but I would imagine it works similar to medical versions (almost certainly because the LTI was never the most advanced software-wise). When measuring speed it will expect the distance to decrease to target to decrease at a proportional rate between pulses (basically the essence of a speed calculation anyway). By sending multiple pulses rather than two the LTI checks it has a "flat" target. Readings with inconsistent speed/distance readings will be discarded.

It has to be understood also with the fact that in normal use there will inevitably be slip readings along with "real" readings due to the diverging size of the laser beam and the ability to move the gun on the tripod. The crosshairs on the video suggest a sniper-like accuracy which almost never exists. The LTI chooses the strongest reading from a mixed field, so even when the gun moves across a target it should still select the reading from the front of the vehicle. Slip readings are only likely to occur with small or very close targets, or if the gun is used at a notable angle to the target vehicle.

However, the only way to confirm would be to get a gun and read the firmware, and even then it is highly likely the firmware is updated as time goes on.
justforthepictures
QUOTE (notmeatloaf @ Tue, 16 May 2017 - 02:08) *
The crosshairs on the video suggest a sniper-like accuracy which almost never exists.

Almost never? When does it exist?
Mad Mick V
Way too late on this one, but I did some background research on LIDAR years ago. One of the most fruitful sources of data was the U.S. Army websites because their gunners were using LIDAR for range finding and IIRC aiming at tanks produced a slip effect. I would check those sites for a published algorithm.

Mick
justforthepictures
QUOTE (Mad Mick V @ Wed, 17 May 2017 - 09:59) *
Way too late on this one, but I did some background research on LIDAR years ago. One of the most fruitful sources of data was the U.S. Army websites because their gunners were using LIDAR for range finding and IIRC aiming at tanks produced a slip effect. I would check those sites for a published algorithm.

Mick

Aren't tanks specifically designed not to be a retro-reflective target? They even have hull and turret shaping designs not to return a signal, plus being coated in anti-radar paint, unlike Mrs Miggin's Zafira which has nice flat surfaces that include a highly reflective VRM back and front.
Mad Mick V
Tell me more about this anti-radar paint and how much I need to spray on my Range Rover (it's really a tank --honest!).

Mick
notmeatloaf
QUOTE (justforthepictures @ Wed, 17 May 2017 - 10:33) *
QUOTE (notmeatloaf @ Tue, 16 May 2017 - 02:08) *
The crosshairs on the video suggest a sniper-like accuracy which almost never exists.

Almost never? When does it exist?

When the return received is entirely the target vehicle rather than a software filtered version.
justforthepictures
QUOTE (notmeatloaf @ Thu, 18 May 2017 - 04:53) *
QUOTE (justforthepictures @ Wed, 17 May 2017 - 10:33) *
QUOTE (notmeatloaf @ Tue, 16 May 2017 - 02:08) *
The crosshairs on the video suggest a sniper-like accuracy which almost never exists.

Almost never? When does it exist?

When the return received is entirely the target vehicle rather than a software filtered version.

There are return signals that aren't dealt with by the software?
notmeatloaf
QUOTE (justforthepictures @ Thu, 18 May 2017 - 14:56) *
QUOTE (notmeatloaf @ Thu, 18 May 2017 - 04:53) *
QUOTE (justforthepictures @ Wed, 17 May 2017 - 10:33) *
QUOTE (notmeatloaf @ Tue, 16 May 2017 - 02:08) *
The crosshairs on the video suggest a sniper-like accuracy which almost never exists.

Almost never? When does it exist?

When the return received is entirely the target vehicle rather than a software filtered version.

There are return signals that aren't dealt with by the software?

Software filtered.

If there is nothing to filter then the no filtering takes place.
justforthepictures
QUOTE (notmeatloaf @ Fri, 19 May 2017 - 00:20) *
QUOTE (justforthepictures @ Thu, 18 May 2017 - 14:56) *
QUOTE (notmeatloaf @ Thu, 18 May 2017 - 04:53) *
QUOTE (justforthepictures @ Wed, 17 May 2017 - 10:33) *
QUOTE (notmeatloaf @ Tue, 16 May 2017 - 02:08) *
The crosshairs on the video suggest a sniper-like accuracy which almost never exists.

Almost never? When does it exist?

When the return received is entirely the target vehicle rather than a software filtered version.

There are return signals that aren't dealt with by the software?

Software filtered.

If there is nothing to filter then the no filtering takes place.

Can you explain what a software filtered version is, compared with one where the software decides that the returned signal is entirely from the target vehicle and doesn't need to intervene?
notmeatloaf
QUOTE (justforthepictures @ Sun, 21 May 2017 - 18:40) *
Can you explain what a software filtered version is, compared with one where the software decides that the returned signal is entirely from the target vehicle and doesn't need to intervene?

If you don't understand how something can pass through a filter but the results is not filtered because nothing has been filtered out then I suggest you ask the nearest person with a grasp of the English language.

For instance, this web page will have gone through at least one filter before you read it but has the page been filtered?
madeirawine
QUOTE (notmeatloaf @ Mon, 22 May 2017 - 14:51) *
QUOTE (justforthepictures @ Sun, 21 May 2017 - 18:40) *
Can you explain what a software filtered version is, compared with one where the software decides that the returned signal is entirely from the target vehicle and doesn't need to intervene?

If you don't understand how something can pass through a filter but the results is not filtered because nothing has been filtered out then I suggest you ask the nearest person with a grasp of the English language.

For instance, this web page will have gone through at least one filter before you read it but has the page been filtered?

Dear notmeatloaf

I think that you are labouring under the impression you are aware of filter technology and terminology; sadly not the case I am afraid.

Filters either pass information through or they prevent information passing through. If information is found at the output of a filter then it has been filtered by that filter.

When information successfully passes through the filter it has still been filtered; it just so happens that the information is what is wanted at the filter output, just because it hasn't been changed doesn't mean it hasn't been subject to filtering action.

If you don't understand how something can pass through a filter but the results is not filtered because even though nothing has been filtered out then I suggest you ask the nearest person with a grasp of the English language...or of course someone who understands filter technology and the terminology thereof.

Back to your discussion on laser technology, even though it bears no resemblance to knowledge of such devices.
notmeatloaf
Aaw, it's nice you registered another account to back yourself up. Or a new member signed up just to immediately post in here.

You know, I think I would agree with you if a third new member signed up to agree with you as well. (hint hint)
southpaw82
QUOTE (notmeatloaf @ Mon, 22 May 2017 - 17:26) *
Aaw, it's nice you registered another account to back yourself up. Or a new member signed up just to immediately post in here.

You know, I think I would agree with you if a third new member signed up to agree with you as well. (hint hint)

If only there was some sort of admin type who could check IP addresses...
notmeatloaf
QUOTE (southpaw82 @ Mon, 22 May 2017 - 20:10) *
If only there was some sort of admin type who could check IP addresses...

IP addresses are attached to a location rather than a person. Everyone with a computer on their desk at work will have at least two IP addresses to use.
southpaw82
QUOTE (notmeatloaf @ Tue, 23 May 2017 - 04:04) *
QUOTE (southpaw82 @ Mon, 22 May 2017 - 20:10) *
If only there was some sort of admin type who could check IP addresses...

IP addresses are attached to a location rather than a person. Everyone with a computer on their desk at work will have at least two IP addresses to use.

Hello Captain Obvious.
notmeatloaf
QUOTE (southpaw82 @ Tue, 23 May 2017 - 08:06) *
Hello Captain Obvious.

I thought you said I was Tea Boy Obvious.
Fredd
QUOTE (notmeatloaf @ Tue, 23 May 2017 - 04:04) *
QUOTE (southpaw82 @ Mon, 22 May 2017 - 20:10) *
If only there was some sort of admin type who could check IP addresses...

IP addresses are attached to a location rather than a person. Everyone with a computer on their desk at work will have at least two IP addresses to use.

They're attached to a computer or other network device rather than a location, unless you're using a rather technical interpretation of location - which your posts in this thread suggests you won't be. Not sure where the "at least two" addresses comes from?
notmeatloaf
QUOTE (Fredd @ Tue, 23 May 2017 - 09:27) *
They're attached to a computer or other network device rather than a location, unless you're using a rather technical interpretation of location - which your posts in this thread suggests you won't be. Not sure where the "at least two" addresses comes from?

Almost every IP address will have multiple computers and devices attached to it, unless they are in physically different locations (or at least different access points).
Fredd
That's the opposite way around from what you said. NAT allows more than one device to use the same external IP address, but not one device to have more than one IP address.
This is a "lo-fi" version of our main content. To view the full version with more information, formatting and images, please click here.
Invision Power Board © 2001-2020 Invision Power Services, Inc.