Well if the camera is calibrated for a van' date=' such that it is a height of 1m off the ground then moves into a new van such that it is 1.2m off the ground then the things error correction algoriths would need recalibrating.

If you want to claim evidence is accurate then you have to make sure it is 100% beyond all reasonable doubt.

[/quote']

The difference in speed reading from a 20cm height difference would be so minute as to be irrellevant and would not constitute "reasonable doubt".

The highest speed reading will be when the vehicle is heading directly towards the camera. If the vehicle is travelling at a slight angle at , for example 45mph , then the reading will be slightly lower like 44. The greater the angle the lower the speed reading. The ideal is to be on a straight road and standing in the midlle of the lane but thats clealy not going to happen.

Moving the camera up or down by a foot is exactly the same effect as being a foot closer or further away to the edge of the road and this can only benefit the driver as no matter where they stand they can't produce a reading thats higher than your actual speed.

It is not irrelevant though as the gun is in a not calibrated state.

If the police want to use a camera in a certain van they should have to calibrate it.

I'm sorry but you could be removing a persons livelyhood, and having done a very large amount of physics due to a chem degree, I can say that 1mph difference could be caused by the weather conditions or the operator tracking a car, or a height difference, or reflectiveness from surface targeted, or even from an external object.

I'm affraid that the laser guns can produce a reading that is higher than that of the vehicle, just by the principle of the dopler effect which is used to calculate speed. I know our local force target vehicles moving away from them as well as towards and often on slopes. They have an algorith that is 'secret' in the guns to correct errors, but how can you trust the algorithm if you don't know what it is. Additionally when the expert witness employed by the prosicution has been the importer for the goods, with no physics background, on a few occasions that i have read up on , you do have to feel there may be a conflict of interests there.

The 20cm was only theoretical amount, and if I was on a jury, should a matter have ever gone that far I would not accept the 'oh it makes almost no difference' line as making the data accurate. Moving a camera up will have the opposite effect of moving it down, so they can't both benifit the driver.

I can see we are going to have to agree to disagree on this one.

Oh and sorry for the long post.

Who said the camera was actually mounted inside a van? It could've been on the kerb for all we know.

I was making a random point that they need to correctly calibrate it for the environment it is being used as well as the prevailing conditions. It wasn't specific to any case.

And wrong.

A police officer can report you for a speeding offence using the wording I mentioned in my post above ' date=' a verbal NIP.

The usual procedure is to report you for the speeding offence and also issue a producer for your documents but these are two separate issues that can be dealt with separately.

If for example a police officer doesn't have the right forms with them that does *not* prevent them from dealing with you for motoring offences , it just means that they can't issue a fixed penalty notice on the spot. They can report you and submit the paperwork required when they return to the station.

In this case it is *likely* that no further action will be taken but by no means certain.[/quote']When I was very young, I got a TS20 for crossing a double white line. I got a verbal NIP exactly as described, and most certainly didn't understand what he meant when he said "you will be reported for ..." until I got the court paperwork and subsequently got done.

Fortunately only 3 points and