“Going 50 Over The Limit”

Bookm, I read that five times and still can't figure it out. I get it up to 62.72 MPH but couldn't figure out the 7 foot bumper to hood line calculation:

88 X = (60 * 95) 5700

The entire thread can be seen here:

But ever mind that... Here's something better!

I have a pdf copy of the ProLaser III Manual. It clearly indicates a speed reading tolerance of +/- 2 kph. It's quite possible this guy should not have been impounded. Of course, we don't know what the officer was using, but if a high-tech device like the ProLaser III can be off 2kph (under perfect test conditions), I'd imagine rolling radar would be even worse.

SWEEP = BS.

I have seen that *EDIT* on the english dudes video.....of course you can get something weird like he does.......100-150ft to the side of the track/road....when not being used properly.

After watching this video and deliberately trying to get "sweep" it is *beeping* impossible while using the equipment properly. I tried it for hours both daylight and night, still nothing. I have tried hitting the side, joint hood and front windshield, still no reading just error msgs.

Easily explained, the lidar requires conditions of sum of least squares to be met, if it falls outside that zone, no reading will be obtained, hence an error message....such as if you hit a vehicle at 180.2metres on the front plate, at the same time it is striking the windshield at 181.2m, the lidar will reject the reading..such as above in "no reading". The different distances will not compute. Similiar to another vehicle travelling directly beside another, the distance of the vehicle changing position will also not fall in the sum of least squares and no reading will be obtained and an error message shown.

There is also the video of the cross hairs moving on the vehicle and the speed being different......no *EDIT* sherlock. I am over 100% confident in that video that the driver did not maintain a constant foot pressure on the gas, the slope (up or down) of the road also makes a slight difference. Oops did the person forget to mention those things in the video

I believe that there is also settings, not available to the officer, to fine tune the sum of least squares data set. Basically a "noise threshold". This is probably set in the factory and could be adjusted by a tech. I think what is funny though, Bear this is for you, is that when you do your alignment check, it is done at 50 and 70 meters. All of the lidar guns in Ontario have a sight that is mounted above the transmitter lens. The alignment check you have performed validates 50 and 70 meters but definitely excludes anything over that distance. Short story long, if you use the gun over 70 meters more of the beam winds up aimed at the windsheild and roof of the car, also over it for that matter. I'll doodle up a diagram if you don't get what I mean.

I understand what you mean.

To sit back and arm chair quarterback what others say and based on this and that, without using the device is not practicable. Or some that think b/c they use it on a track from 100ft away is also not practicable.

I had to take a course, I have used it almost every shift for the past 7yrs, I stand by the equipment, it does not make errors. I have experimented with "those that think they know" perceptions errors etc, with no validity to them.

It is about time some people just looked at something they have purchased.....called a speedometer......then look along the side of the road for another thing.......the posted speed limit....and not just the speed limit, but the word under it.......which says MAXIMUM ...not minimum

I think that it still comes down to the fact that a black law is enforced in a gray, or grey, way.

Grey/gray....you are talking about speed limit enforcement. I'm guessing you mean that everyone 1km over should be getting a ticket? Some days I can not keep up as it is...starting at 20 overs on secondary hwys.

Bring back photo radar then and set the camera to the limit. It would then pick off everyone and no one would have to worry about demerit points......further, think it's a tax grab.....each driver/owner has their own choice to drive below the speed limit and avoid it altogether.

Tager's boyfriend had his car impounded because the officers speed equipment displayed 51kph over the limit. I doubt ANY manufacturers manual will claim to be more accurate than 2kph (as per the Pro Laser III manual) so it's quite possible he was doing 49kph over the limit. So, sure, he should have received a hefty fine, but not the extreme penalties associated with a "racing" charge.

So there's only two possible conclusions to be made here:

1) The officer isn't trained well enough to know the specifications of his own equipment.

2) He really doesn't give a rats ass and just wants to brag to the boys about how he nailed another one today.

Either one is unacceptable and should result in disciplinary action. He should also be compelled to provide financial restitution for the towing, impoundment, and other fees associated with his error. The police may think they can just paint everyone with a broad brush and enforce law as they see fit. There are different penalties for different speeds. They have to be applied appropriately.

Bookm wrote:Tager's boyfriend had his car impounded because the officers speed equipment displayed 51kph over the limit. I doubt ANY manufacturers manual will claim to be more accurate than 2kph (as per the Pro Laser III manual) so it's quite possible he was doing 49kph over the limit. So, sure, he should have received a hefty fine, but not the extreme penalties associated with a "racing" charge.

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With my handy dandy cosine calculator with about 5-10% angle (as one can not be directly in the path of the vehicle and have the lidar 3ft off the ground) the reduction via cosine is 1.2mph = 2km/hr. So even if the lidar is 2km faster, still comes out to the true speed.

It should be stressed again that with the LIDAR, the angular or cosine effect is always in the motorist's favor.

And it was NOT racing he was charged with!!

With all the alledged bad things about 172.......surely everyone knows that they should not even be so close to 50 over.

One motorist was luckier than *EDIT* the other night. Clocked at 164km/hr, just caught a glimpse of me and started braking, I was delayed on getting out behind due to a transport starting to pass. I called ahead to 2 units. Lost site due to a curve in the road. Co-worker stopped the vehicle just past the curve now at 129km/hr.

According to my handy dandy calculator, in order for you to achieve a 5 degree angle at 400 meters to target you would need to be 35 meters from the road.

Tan (angle)= opposite/adjacent.

So, we multiply both sides by 400 (just an example number) and we get 400 times Tan 5 degrees=34.99 blah,blah. I think you would be hard pressed to catch a lot of action 35 meters from the road bear. The charge should be 2 KMH less then the gun reading. I have yet to see officers using their lidars in the bushes.......... Sidewalks yes, bushes mmmmmmm no.

Yes, engineering background. You can even punch the number through your windows calculator.

Reflections wrote:According to my handy dandy calculator, in order for you to achieve a 5 degree angle at 400 meters to target you would need to be 35 meters from the road. .

SO what your saying is stop using things I find on the internet...go to my office and get my training stuff.....copy

Common geographical features such as a crown in the road or a bend in the road could quite easily exclude the cosine factor from the equation. Of course we have no idea of the topography in this case, but I doubt the officer will remember it either, 6 months down the road

The benefit of the doubt should always favor the defendant.

hwybear wrote:

Reflections wrote:According to my handy dandy calculator, in order for you to achieve a 5 degree angle at 400 meters to target you would need to be 35 meters from the road. .

SO what your saying is stop using things I find on the internet...go to my office and get my training stuff.....copy

Just putting everything into perspective. The angles you are refering to are seldom, if ever present in lidar speed "traps".

Bookm wrote:Common geographical features such as a crown in the road or a bend in the road could quite easily exclude the cosine factor from the equation. Of course we have no idea of the topography in this case, but I doubt the officer will remember it either, 6 months down the road ]

A hill will not eliminate cosine. A curve will only eliminate cosine in stationary mode IF the unit is set up at identical height to the vehicle, obtains a straight head on shot, prior to the vehicle entering the curve.....so ideally is the pop up cop holes (person holes in centre of road)