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-   -   Laser distance, angle & operation (https://www.speedtraphunter.net/police-laser-lidar-enforcement/1809-laser-distance-angle-operation.html)

esprit888 2009-09-16 12:00

HI Michael,
I received a phone call from the relevant PD and was informed that the type of laser used was the Ultralite LRV (sounded like a V but could have been a B as it was a voice message)

Veil Guy 2009-09-16 13:34

That would be LRB.

VG

esprit888 2009-09-16 18:08

Correct, it was a ULtralyte LR B The specs for this model indicate a Maximum target distance of 1000m so strictly speaking it is within the capabilities of the unit however, i have found case law that limits the distance to 500 FEET Additionally all reccomendations i have sourced thus far recommend use of a tripod or pole for distances over 500 so i will attempt to obtain the training manual or opeartors guide for the ULtralyte LR B to see what it says (unless anyone on here has a copy ?)

Veil Guy 2009-09-16 18:37

Mike and I spoke today on the phone about your particular circumstance and I believe we are of like mind as to what potentially happened, although I won't attempt to speak for him.

It has been my experience with LTI that of all of the police lidar manufacturers (I believe they were the first) that their units possess the highest or most stringent error checking and QoS of any manufacturer.

LTI was the company, I believe, most exposed to the judicial notice process and successfully overcame challenges to their technology many years ago.

As a consequence, I believe the likelihood of an erroneous speed reading is nil.

What Mike and I both believe is a greater possibility is the following:

You pass another vehicle (or two) as you approach an incline and continue to rise in altitude making your vehicle directly visible to the targeting officer (where normally he would not have had a direct line of sight).

The vehicle or vehicles you passed "sped" up to follow up (perhaps at a higher or much higher speed that you were traveling yourself).

The officer (having a line of sight to your vehicle) targets or attempts to target you at this great distance with a lidar beam divergence of nearly 3 metres at that distance.

Your vehicle has a lower lidar cross section than the other vehicle behind you.

A significant amount of the lower portion of the spherical beam strikes one of these other vehicles and a speed reading is obtained off of that vehicle.

Having watched you pass these vehicles, the officer makes the assumption that your vehicle was responsible for the speed reading.

And you are subsequently cited for the violation.

If this sounds plausible to you, as well, I would be inclined to argue the case of these technical points (about the quality of the speed measurement made by the officer).

Given the proximity of the other vehicles and the fact that they may have been extremely close together from the vantage point of the officer, it sounds like a poor targeting scenario with enough question as to whether it should have been even made.

I am pleased that you have found a 500 meter guideline which your officer far exceeded. I am even inclined to reach out to a contact of mine at LTI and get their take on this event as it is not a poor reflection of the the LTI 100LRB (it did its job), but more about how it may have been used in error by the officer.

What do you think?

esprit888 2009-09-16 19:08

It sounds like a plausable explanation, in particular as there are two points i have left out, which having researched the subject may be relevant? The vehicle i was driving has a very very low profile, is a two seat convertible (the roof was down at the time) is made of fiberglass and has a diffuser type tinted licence plate cover. The two vehicles i passed were both significantly larger,one being a pick up truck with a canopy.

One other question was raised on another forum so today i parked a vehicle in the exact spot the PC was. It was hidden between two bushes and the officer was shooting between two sections with long foliage. Is it possible that wind movement of the foliage across the face of the beam could have caused an error? ( i will post pictures once it stops raining!) A letter from LTI would be the best case scenario for me as all along i felt it was the distance, coupled with the three vehicles, that resulted in the erroneous reading being recorded. I have researched several laser specification manuals and approx half do state that at distances over half of the max range a tripod or pole type support 'would be helpful'. What do you think the chances are of getting a letter or email from the manufacturer saying something along the lines of when a tripod should be used and what distances should not be exceeded when taking speed reading (i imagine it would be part of the training ? other LTI manuals do state the distances to use)


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