PePiPoo Helping the motorist get justice

Welcome Guest ( Log In | Register )

A Review Of Laser Speed Meters, A critical look at Laser Speed Meters
Paul D. Lee
post Thu, 10 Jul 2008 - 21:25
Post #1


Member


Group: Members
Posts: 57
Joined: 14 May 2008
Member No.: 19,550



For ease of reference, here is the latest copy of my Laser Speed Meters Report.

Attached File  report_v1_2_rqp.pdf ( 2.18MB ) Number of downloads: 3094


Attached File  beam_spread_wrong_clip_1_small.mpg ( 3.48MB ) Number of downloads: 2434

Attached File  beam_spread_wrong_clip_2_small.mpg ( 3.43MB ) Number of downloads: 1527

Attached File  beam_spread_correct_clip_1_small.mpg ( 2.91MB ) Number of downloads: 1562


(Edited 15 July 2008, with latest version of report, and example "Beam Spread" Clips)

This post has been edited by Paul D. Lee: Wed, 30 Jul 2008 - 22:06
Go to the top of the page
 
+Quote Post
5 Pages V  « < 2 3 4 5 >  
Start new topic
Replies (60 - 79)
Advertisement
post Thu, 10 Jul 2008 - 21:25
Post #


Advertise here!









Go to the top of the page
 
Quote Post
Yvan Dutil
post Fri, 22 Jan 2016 - 16:48
Post #61


New Member


Group: Members
Posts: 8
Joined: 17 Jan 2016
From: Québec
Member No.: 81,812



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.

This post has been edited by Yvan Dutil: Fri, 22 Jan 2016 - 17:00
Go to the top of the page
 
+Quote Post
bama
post Fri, 22 Jan 2016 - 17:53
Post #62


Member


Group: Members
Posts: 28,926
Joined: 29 Nov 2005
Member No.: 4,323



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)


--------------------
Which facts in any situation or problem are “essential” and what makes them “essential”? If the “essential” facts are said to depend on the principles involved, then the whole business, all too obviously, goes right around in a circle. In the light of one principle or set of principles, one bunch of facts will be the “essential” ones; in the light of another principle or set of principles, a different bunch of facts will be “essential.” In order to settle on the right facts you first have to pick your principles, although the whole point of finding the facts was to indicate which principles apply.

Note that I am not legally qualified and any and all statements made are "Reserved". Liability for application lies with the reader.
Go to the top of the page
 
+Quote Post
CL22
post Fri, 22 Jan 2016 - 19:14
Post #63


New Member


Group: Members
Posts: 7
Joined: 22 Jan 2016
Member No.: 81,944



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.
Go to the top of the page
 
+Quote Post
southpaw82
post Fri, 22 Jan 2016 - 19:23
Post #64


Member


Group: Members
Posts: 31,001
Joined: 2 Apr 2008
From: Not in the UK
Member No.: 18,483



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.


--------------------
Moderator

Any comments made do not constitute legal advice and should not be relied upon. No lawyer/client relationship should be assumed nor should any duty of care be owed.
Go to the top of the page
 
+Quote Post
Yvan Dutil
post Wed, 27 Jan 2016 - 22:10
Post #65


New Member


Group: Members
Posts: 8
Joined: 17 Jan 2016
From: Québec
Member No.: 81,812



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.
Go to the top of the page
 
+Quote Post
notmeatloaf
post Tue, 16 May 2017 - 02:08
Post #66


Member


Group: Members
Posts: 1,912
Joined: 4 Mar 2017
Member No.: 90,659



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.

This post has been edited by notmeatloaf: Tue, 16 May 2017 - 02:12


--------------------
No longer posting - please do not PM for advice.
Go to the top of the page
 
+Quote Post
justforthepictur...
post Wed, 17 May 2017 - 09:33
Post #67


Member


Group: Members
Posts: 893
Joined: 23 Aug 2010
From: Louis Walsh's bathroom
Member No.: 40,004



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?


--------------------
'Speed Kills' simply means, hit something or someone fast enough and it will result in a fatality.
Go to the top of the page
 
+Quote Post
Mad Mick V
post Wed, 17 May 2017 - 09:59
Post #68


Member


Group: Members
Posts: 8,500
Joined: 28 Mar 2007
Member No.: 11,355



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
Go to the top of the page
 
+Quote Post
justforthepictur...
post Wed, 17 May 2017 - 12:15
Post #69


Member


Group: Members
Posts: 893
Joined: 23 Aug 2010
From: Louis Walsh's bathroom
Member No.: 40,004



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.

This post has been edited by justforthepictures: Wed, 17 May 2017 - 12:33


--------------------
'Speed Kills' simply means, hit something or someone fast enough and it will result in a fatality.
Go to the top of the page
 
+Quote Post
Mad Mick V
post Wed, 17 May 2017 - 13:20
Post #70


Member


Group: Members
Posts: 8,500
Joined: 28 Mar 2007
Member No.: 11,355



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
Go to the top of the page
 
+Quote Post
notmeatloaf
post Thu, 18 May 2017 - 04:53
Post #71


Member


Group: Members
Posts: 1,912
Joined: 4 Mar 2017
Member No.: 90,659



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.


--------------------
No longer posting - please do not PM for advice.
Go to the top of the page
 
+Quote Post
justforthepictur...
post Thu, 18 May 2017 - 13:56
Post #72


Member


Group: Members
Posts: 893
Joined: 23 Aug 2010
From: Louis Walsh's bathroom
Member No.: 40,004



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?


--------------------
'Speed Kills' simply means, hit something or someone fast enough and it will result in a fatality.
Go to the top of the page
 
+Quote Post
notmeatloaf
post Fri, 19 May 2017 - 00:20
Post #73


Member


Group: Members
Posts: 1,912
Joined: 4 Mar 2017
Member No.: 90,659



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.


--------------------
No longer posting - please do not PM for advice.
Go to the top of the page
 
+Quote Post
justforthepictur...
post Sun, 21 May 2017 - 17:40
Post #74


Member


Group: Members
Posts: 893
Joined: 23 Aug 2010
From: Louis Walsh's bathroom
Member No.: 40,004



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?

This post has been edited by justforthepictures: Mon, 22 May 2017 - 13:37


--------------------
'Speed Kills' simply means, hit something or someone fast enough and it will result in a fatality.
Go to the top of the page
 
+Quote Post
notmeatloaf
post Mon, 22 May 2017 - 13:51
Post #75


Member


Group: Members
Posts: 1,912
Joined: 4 Mar 2017
Member No.: 90,659



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?

This post has been edited by notmeatloaf: Mon, 22 May 2017 - 13:51


--------------------
No longer posting - please do not PM for advice.
Go to the top of the page
 
+Quote Post
madeirawine
post Mon, 22 May 2017 - 14:54
Post #76


Member


Group: Members
Posts: 29
Joined: 22 May 2017
Member No.: 92,120



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.
Go to the top of the page
 
+Quote Post
notmeatloaf
post Mon, 22 May 2017 - 16:26
Post #77


Member


Group: Members
Posts: 1,912
Joined: 4 Mar 2017
Member No.: 90,659



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)


--------------------
No longer posting - please do not PM for advice.
Go to the top of the page
 
+Quote Post
southpaw82
post Mon, 22 May 2017 - 19:10
Post #78


Member


Group: Members
Posts: 31,001
Joined: 2 Apr 2008
From: Not in the UK
Member No.: 18,483



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...


--------------------
Moderator

Any comments made do not constitute legal advice and should not be relied upon. No lawyer/client relationship should be assumed nor should any duty of care be owed.
Go to the top of the page
 
+Quote Post
notmeatloaf
post Tue, 23 May 2017 - 03:04
Post #79


Member


Group: Members
Posts: 1,912
Joined: 4 Mar 2017
Member No.: 90,659



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.

This post has been edited by notmeatloaf: Tue, 23 May 2017 - 03:04


--------------------
No longer posting - please do not PM for advice.
Go to the top of the page
 
+Quote Post
southpaw82
post Tue, 23 May 2017 - 07:06
Post #80


Member


Group: Members
Posts: 31,001
Joined: 2 Apr 2008
From: Not in the UK
Member No.: 18,483



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.


--------------------
Moderator

Any comments made do not constitute legal advice and should not be relied upon. No lawyer/client relationship should be assumed nor should any duty of care be owed.
Go to the top of the page
 
+Quote Post

5 Pages V  « < 2 3 4 5 >
Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



Advertisement

Advertise here!

RSS Lo-Fi Version Time is now: Thursday, 28th May 2020 - 14:31
Pepipoo uses cookies. You can find details of the cookies we use here along with links to information on how to manage them.
Please click the button to accept our cookies and hide this message. We’ll also assume that you’re happy to accept them if you continue to use the site.