Tempest 0 Posted September 10, 2005 The German AA, ADAC, have just published their findings after having tested several of these devices and what can go wrong in their use in this month's club magazine. These guns, as you know, work on the principle of firing a light beam towards a car (best results only when aiming at the license plate), which then is reflected off a reflective area on the car, such as the license plate, and the returning light beam is picked up by the gun, from which it can then calculate the speed of said car. Just a few of the findings: If the gun isn't accurately aimed at the license plate of a car, behind which there is another vehicle, but a bit higher, chances are high that the gun will actually measure the speed of the 2nd car! This happens particularly when the person using such a gun aims at the A-pillar or a headlight. If the gun is aimed at the windscreen instead of at the license plate, the laser beam would travel straight through the car and would hit any vehicle immediately behind it with a suffiently large reflection area! In the past it's happened that the wrong recorded speeds were associated to the wrong car, and the wrong car could receive the penalty! The laser gun would even work on a vehicle where the entire front end had been treated with non-reflective material, the laser would simply bounce off another vehicle behind the first, no matter how small a reflective area the 2nd vehicle would have!. Bear in mind that these laser guns are aimed at cars anywhere up to 1 km away! Even well-trained sharp shooters without tripods will find this a challenge, let alone a copper or some OAP, none of whom use tripods. The ADAC had also asked a calibration institute how many of these devices were out of calibration. The finding was rather shocking: In 2004 alone, having tested 1687 guns 1.8%, i.e. 30 guns, had to be repaired before they had the required accuracy again. Especially the accuracy of the aiming mechanism was noteworthy: 7% of the guns were found to have inaccurate aiming mechanisms. The plod were still using these guns! The German ADAC is therefore demanding photo evidence to accompany every laser gunned car that's been found to be speeding. If the plod cannot provide photo evidence, the ADAC at least demand the use of tripods to minimise aiming errors. Ideally these guns should only be used whenever the car it is aimed at has no other vehicles around it. Well let's see whether they can lobby this one through, I can't see it happening, as like overher, the German pold and government simply need the revenue from allegedly speeding vehicles, never mind whether the car was actually speeding. Tempest Quote Share this post Link to post Share on other sites
polog40racer 0 Posted September 10, 2005 Thats very interesting reading. My mate got out of his ticket by going to court. A copper jumped out on him and 'got him' with a radar gun, he blagged it though due to explaining the 'doppler phenomenon' principles to the judge and got the case got dismissed. basically the copper fired first then moved position, so due to the doppler effect, the return signal is now shorter therefore idicating a higher speed. Although he works (with me) on aircraft radar systems for a living, which is why it got thrown out. Like Tempest says, it needs to be on a tripod or a stable platform, if it is not then it'll cause irregular readings. Quote Share this post Link to post Share on other sites
chubbybrown 0 Posted September 11, 2005 This is why many bikers drive with main beam on as the laser supposedly cant get a fix on the bike being so narrow ? what do you minds think of this ? Quote Share this post Link to post Share on other sites
