Stopping two cars

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Bookm
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Unread post by Bookm on

I'm willing to bet the officer just assumed you were traveling at the same speed as the lead car.

I wouldn't put a lot of thought in to a defense until you read the Disclosure. The type of equipment the officer used will make all the difference in how you handle your questioning.

I suspect the Crown will be anxious to offer a plea to a lesser charge, but I would hold off on accepting that until you carefully go over the officers notes. Bear might be correct in that his equipment is 100% foolproof, but how it is used is definitely up for argument.


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hwybear
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Unread post by hwybear on

Bookm wrote:Bear might be correct in that his equipment is 100% foolproof, but how it is used is definitely up for argument.
My offer of you coming to visit when I'm working and showing you the tools is still there!!

Once you see it and use the equipment, you will then understand the equipment better AND know why it is accurate! AS compared to the videos show on various sites and that they are not used properly.
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Reflections
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Unread post by Reflections on

hwybear wrote:
Bookm wrote:Bear might be correct in that his equipment is 100% foolproof, but how it is used is definitely up for argument.
My offer of you coming to visit when I'm working and showing you the tools is still there!!

Once you see it and use the equipment, you will then understand the equipment better AND know why it is accurate! AS compared to the videos show on various sites and that they are not used properly.
Those video's still show the gun is not fool proof. You could be using it properly and still have unseen influences. Until you can see the beam while in flight questions remain. The amount of "noise" filtering going on is unbelievable.

Don't worry there Imax, I can see the limitations of the guns.
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Bookm
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Unread post by Bookm on

Last month I received data that showed a survey bar in the middle of the street. When I asked my party-chief, "What the heck?", he came to the realization that the laser reflected off the taillight of a passing car instead of his prism.

This may not happen with police systems, but a JP might entertain the possibility :P

Will let you know when I get my next tick' ;)

Now,... when I come I want you to show me how you can ID speeds of two cars in a line using RADAR, hehehe


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hwybear
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Unread post by hwybear on

Reflections wrote: You could be using it properly and still have unseen influences.
Absoletely not!

If you have a video that I can see to the contrary PM me the link. And not the england guy who stands 50 seats away from the edge of the road.
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Imax
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Unread post by Imax on

I’m a nerd by nature, :oops:, and last night I did a few computations. The officer was standing at approx. 10m off the road. Minimum stooping distance for a car going 130kph is just over 80m, screech, screech, panic brake. Controlled stopping distance for a car going 130Kph is about 200m to 400m. I was about 100 to 200 feet behind the lead car, min 30m to max 100m. The officer could have measured lead car speed at 300m, 400m, or 500m. If I remember my trig ok, best case scenario is that when the officer moved his laser from the lead car to my car (following the speeder), the laser would need to be moved by less than ½ of a degree. Most probable scenario is 0.1 to 0.2 degrees. He must be s sharp shooter. 8)


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hwybear
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Unread post by hwybear on

Imax wrote: He must be s sharp shooter. 8)
It helps that the lidar has a scope that is magnified 8 times.
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ticketcombat
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Unread post by ticketcombat on

Bear, first I want to state that I've never held or used a lidar gun so all of my knowledge is only from what I've read. With that in mind, here are some questions for you:
  • The scope is offset from where the laser pulse is emitted. How is it aligned for different distances? I'm thinking of every sniper movie I've ever seen, even Day of the Jackal (the original) where he's shooting the pumpkin from a distance. He has to keep modifying the scope settings to get the aim right. How do you align the scope when your road targets can be at 50m or 250m?
  • The fixed distance test - is there an alignment mark on the unit so that it measures precisely where the pulse is emitted from. If the tester has his foot on the line, he could be leaning forward or back (not perfectly vertical). How do you compensate for this? Is the unit placed on a fixed stand?
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Reflections
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Unread post by Reflections on

hwybear wrote:
Reflections wrote: You could be using it properly and still have unseen influences.
Absoletely not!

If you have a video that I can see to the contrary PM me the link. And not the england guy who stands 50 seats away from the edge of the road.
I will hunt...... The nature of lidar is such that it will bounce off of everything and anything. All the manufacturer's claim 1/3 third of a second readings, yet none will say exactly how they are filtering the noise. There is too much left out to conclusively say they are perfect.
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Unread post by Proper1 on

ticketcombat wrote:The scope is offset from where the laser pulse is emitted. How is it aligned for different distances?
I'm no great fan of having laser beams pointed at me while I'm driving, but I don't think parallax is an issue. The laser beam is not significantly affected by gravity and has no wind resistance, so the "error" between the sightline of the scope and the centre of the beam would be a constant 2.5cm (or whatever is the distance between the two at the unit) and easily compensated out in the course of signal processing. It is only if Officer Friendly were trying to shoot me in the head with his long-range rifle as I drove on my unconcerned way down the 401 that he would have to consider bullet rise and drop over time and distance, wind effects, possible legal complications, and the effects of parallax error with changing distance to target.

Whether or not they're accurate in measuring speeds, the use of lasers around highways bugs me. Unfriendly folks are using them to disrupt big-time soccer games by shining them at players to momentarily blind them, and the same delightful hobby is showing up around airports, with pilots on short finals being the target. How is the highway situation different?


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Bookm
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Unread post by Bookm on

Hmmm... I've been thinking about getting a laser parking system to assist with those tricky parking situations. Gee, I hope the Laser Pro Park system won't negatively affect the police lasers ;)


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Unread post by BelSlySTi on

Bookm wrote:Hmmm... I've been thinking about getting a laser parking system to assist with those tricky parking situations. Gee, I hope the Laser Pro Park system won't negatively affect the police lasers ;)
Is that what they're calling them now :o
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Reflections
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Unread post by Reflections on

Proper1 wrote:
ticketcombat wrote:The scope is offset from where the laser pulse is emitted. How is it aligned for different distances?
I'm no great fan of having laser beams pointed at me while I'm driving, but I don't think parallax is an issue. The laser beam is not significantly affected by gravity and has no wind resistance, so the "error" between the sightline of the scope and the centre of the beam would be a constant 2.5cm (or whatever is the distance between the two at the unit) and easily compensated out in the course of signal processing. It is only if Officer Friendly were trying to shoot me in the head with his long-range rifle as I drove on my unconcerned way down the 401 that he would have to consider bullet rise and drop over time and distance, wind effects, possible legal complications, and the effects of parallax error with changing distance to target.

Whether or not they're accurate in measuring speeds, the use of lasers around highways bugs me. Unfriendly folks are using them to disrupt big-time soccer games by shining them at players to momentarily blind them, and the same delightful hobby is showing up around airports, with pilots on short finals being the target. How is the highway situation different?
Lidar used by officers is invisible to the naked eye. You can however use nightvision to see them. I wonder why officers are not using nightvision to align the scopes???

Paralax become an issue when you aim out at say 500m or so when the beam will be higher then the target, i.e lisence plate. If an officer wants to use the gun past that distance then all the power to him and easier for me to beat in court.

One thing though. I know that light travels at a constant speed in a vacuum. The atmosphere is not a vacuum. Dirt, smog.....all those airbourne particles can effect light. How would this be compensated for....? I know you're coming back to this 'bear so..... The further away a target is from the gun the more the "light" is going to slow down, simple physics. Is there a setting you have for "smoggy" days??? I know there are foul weather modes on different models. You cannot compensate for the unknown.
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Radar Identified
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Unread post by Radar Identified on

Hopefully they've tested the lidar units to ensure that they won't blind a driver who's being clocked.

Officer: "Why didn't you stop when I waved you over?"
Driver: "I was driving along and suddenly I couldn't see!!"

:shock:

The hand-held laser pointers, the type that've been directed at aircraft, can do a lot of damage. Last winter we were landing in Detroit and some moron was shining them at inbound aircraft. We asked for a different runway, whose approach course was over a mile from where this idiot was. So did everyone else after the first plane reported being illuminated by a laser. Knowing the potential consequences of having a laser beam directed at your eyes, you'd really hope that the types in the lidar units are almost certain not to do the same sort of thing.


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Unread post by hwybear on

ticketcombat wrote:[*]The fixed distance test - is there an alignment mark on the unit so that it measures precisely where the pulse is emitted from. If the tester has his foot on the line, he could be leaning forward or back (not perfectly vertical). How do you compensate for this? Is the unit placed on a fixed stand?[/list]
Our fixed distance is done at the corner of the wall. The lidar is held flush with the wall or on a tripod flush with the wall. The known target distance was measured out by tape to where posts were placed in the ground.




Above is merely a suggestion/thought and in no way constitutes legal advice or views of my employer. www.OHTA.ca


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