Speed Trap Hunter Forum: Best Radar Detectors, Laser Jammers, Laser Detectors, Speed Cameras Forum

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

Michael B 2009-09-17 12:51

I doubt that you will receive anything in writing from an LTI or any other Laser company representative as no one is going to go on record with a statement to anyone other than a law enforcement department especially if it contradicts what may have been spelled out in the operators manual, however if there is something in the operators manual, I would suspect that should give you the information you need.

Good luck and keep us posted.

esprit888 2009-09-17 13:18

Thanks again Michael, I must confess that this has become something of an obsession now, as an engineer I want to make sense of what I believe was an error. If I am overposting I apologise but I would like to locate the optimum distance (in this I also apologise to Craig, as perhaps I am searching for the answer I want :)) I understand a letter is not realistic but my request would have been along the lines of the factory training guidlines, which may include such information as : 'Do not exceed XXX meters without a tripod or do not exceed XXX with other vehicles within XXX proximity'

I was able to obtain the users manual for the LTI UL LRB (2nd edition 2002) unfortunately it only gives the specifications for min & Max range(Even then its a little vague as it states an 'absolute maximum of ABOUT 1000 meters and can vary dependant upon various factors such as target') and does not indicate an optimal distance or a distance that should not be exceeded hand held (such as can be found in the 20/20 or 100 manuals) I should have saved myself a bunch of time by simply going to the bottom of this page and clicked on similar postings as there is a very informative blog copy from the NMA (sections pasted below)

‘While it’s possible to clock a target that is 2000 to 3000 feet away the speed reading is of dubious accuracy and highly prone to error. On a clear day with no other traffic in sight a good laser operator can obtain reasonably accurate readings out to 1200, perhaps 1500 feet. However, if there are other vehicles present those distances should be halved.’

‘Remember, at distances in excess of 700-800 feet the laser beam is easily large enough to not only be reflecting off of different parts of the target vehicle (which are simultaneously different distances from the laser gun), but also off of other vehicles, some traveling at different speeds. At distances in excess of 800 feet, the laser operator has no way of knowing what vehicle surfaces or entire vehicles are responsible for the laser speed readings, especially if other vehicles fall within the scope of the laser beam.’

‘A vehicle without a front license plate and a low sloping hood, think Corvette, has to be much closer before a good laser reading can be made. However, at distances in excess of 800-900 feet the license plate is indistinguishable from the car as a whole and the laser beam is washing over the entire vehicle.’

‘In an honest courtroom, any laser reading in excess of 800 feet would not be accepted for evidentiary purposes. The State of New Jersey has set the limit at 1000 feet, which is a step in the right direction. The rest of the country is oblivious to the limitations of this technology, with judges and legislators believing the propaganda, instead of exercising the caution and judgment we have entrusted them to exercise on our behalf.’

esprit888 2010-10-17 17:36

Day in court
 
Well the wheels of justice do indeed turn slowly, but after just over a year of originally posting I had my day in court. I would like to say that everything in this post is solely my 'personal opinion' based on my experience with this particular ticket. I researched everything I could find in the year I had to wait and my opinion is that the entire lidar/laser system of ticketing motorists in my province is seriously flawed. Many books on the systems employed are very useful but the bottom line is that Lidar has its limitations and the primary, but not sole, cause of errors is in its incorrect use. I managed to go on a ride along and observed whilst numerous erroneous tickets were issued (980 meters whilst sweeping from left to right through trees, come on!) we played around and managed to get the usual rock traveling at 60 and sweep error is so easy to obtain without error readings I am surprised that anything over 1000 feet is even considered. The New Jersey case law (Judge Stanton ruling) is actually highlighted and forms a part of the powerpoint presentation for the officers training yet its routine to ticket over 2000 feet. Now those with interests in the devices will no doubt heap scorn on the operators however the manufacturers themselves are deliberately vague regarding distance limitations for hand held readings (obviously one persons steady aim is not the same as the guy who has had his 4 double espressos that morning) A look at the UL LRB manual shows little to no mention of beam divergence and I attended over 12 traffic court sessions prior to mine where each and every officer testified (reading from a prepared traffic court checklist) that the device is ‘vehicle specific with a beam width of 0.5 of a meter at 1km’, which is totally false at 3 milliradians. I beat my ticket without too much of a problem because I educated myself about the devices, and whilst I am obviously pleased with the outcome I came away feeling as though I have more questions than answers. Where I live has just introduced the toughest speeding laws in the country, If you are caught travelling at more than 40 KPH over the posted speed limit your vehicle is immediately seized and impounded for one week, and the fine is a minimum of $500. Factor in the towing and impound charges, your taxi home, loss of income, fine and increased insurance and you are looking at a 5 thousand dollar bill. Some would say it’s deserved if you were indeed exceeding the limit by 40 or more, but the way the readings are taken many are not. The law in my province is very clear with regards to the start/end of shift testing accompanied by a test before and after a ticket is issued but in reality this is seldom practiced (even though it is supported by case law) It would appear, in my opinion, that the police and courts are aware that the use of lidar results in a far from flawless reading but that as long as it results in far more convictions than not guilty verdicts then it remains both a deterrent and a revenue generator.

SpeedTrapper 2011-12-08 23:39

Careful...

1. Not every State requires officers to be scientific experts on the operation of the Lidar, only the practical operation.

2. You would be hard pressed to find even the cheapest current model lidar painting more than a 3' target at 1000'.

3. A good officer is taking more than one reading and/or tracking the violator vehichle for a long enough to establish a speed.

4. Can't speak for others...but fishing for speeders is good enough that I don't bother with any violators that I'm not 100% on.

5. Not every State cares about distance. Depending on traffic, weather, and road layout, and equipment being used...it is super easy to get people at 1,500-2,000 feet...and easy to get people at 2,500-3,000 feet if you have a magnified scope and steady (rest) the lidar on the edge of your window. That said, I prefer 1,000-1,200 feet for my final reading...but it is nothing to identify people at 2,000 feet, hit them again around 1,500, and then take final readings around the 1,000-1,200 foot mark. It you were speeding at 2,000...speeding at 1,500...and still speeding at 1,200...it is a pretty safe bet that you are speeding :-)


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