Gatso vs Talivan. Evidence problem?

[deltaf]

Gatsos as we all know (and dont love) work by radar or loops in the road, allied to lines drwan on the road to give "backup" evidence that you were indeedy exceeding the trigger threshold for the scamera.

Talivans on the other hand use no such lines.
Question: How do WE know that the laser gun IS working correctly, backed up by PHOTO evidence of the distance travelled?

Answer: We dont. They "say" you were doing this speed, but guess what? Theres NO lines on the road to prove it. Also the lack of any lines goes to show that this "spot" isnt actually a blackspot at all,(cant be bothered to either sign it or mark it as such) but just a random area picked for best revenue generation.
A possible get out clause perhaps?

After all, technology IS NOT as infallible as theyd like us to believe......

[Plotloss]

Wasnt there a case somewhere where they pointed the gun at the court room wall and it recorded 2mph?

[deltaf]

Yep...in the US. Prosecution was having a field day until the defence pointed it at the back court room wall and got a 4mph reading.....case dismissed.

Its just the fact that theres NO corroborating evidence to actually backup the lasers indicated speed readings..... Must surely be suspect, as its NOT beyond reasonable doubt that you were doing that speed or that the equipment is accurate.
I dont really give a toss what "proof" they offer in the way of certs etc, it CAN still be wrong, either thru deliberate misuse (south africa), and netherlands (banned device) as they often point it at an object to get a "range" reading, but its not at all clear (from what ive read/heard/been told) what the reding represents as its open to interpretation regarding either range function or speed function.

Trust NOTHING those basts tell you.

[gh0st]

very true statement there but all it seems to take is to get the from the company directors board and get them into court.

Once they "say" its accurate, thats all it takes.

Seems that the courts, the government, and the whole judicial system is based on the bribary of speed tickets.

[206xsi]

Don't the lasers work on the doppler effect? Which basically works on the difference in wavelength returned due to the speed of the body it's reflected off.

So distance doesn't count (although it still does with handheld radars - which must wobble!?)

[gh0st]

206xsi said:

Don't the lasers work on the doppler effect? Which basically works on the difference in wavelength returned due to the speed of the body it's reflected off. So distance doesn't count (although it still does with handheld radars - which must wobble!?)

In theory if the object that the light was hitting wobbled slightly it could cause a hell of a difference in the return lightwave pattern.

So 42 could be read as 55 and because these devices work on the entirely scientific and well thought basis of "because they just do" backed up by "£££££££" - no argument will stand up in court.

[Mr2Mike]

206xsi said:

Don't the lasers work on the doppler effect? Which basically works on the difference in wavelength returned due to the speed of the body it's reflected off. So distance doesn't count (although it still does with handheld radars - which must wobble!?)

No, the radar guns used doppler effect as it's rather easy to extract the difference frequency with an RF mixer.

However, with a laser, detecting and measuring the (miniscule) wavelength shift of the returned light in a small (relatively) inexpensive device is just not practical. Instead the laser guns work out the change in transit times of very narrow pulses of light. The fact that the range of wavelengths that the device accepts is fairly wide (compared to line width of the laser) is the reason why laser jammers can made using high powered IR LED's rather than laser LED's.

[kevinday]

As regards DeltaF's original question, I think you will find the laser is backing up the operator's opinion that you were going too fast.

[cptsideways]

I recently spoke to a pair of Mobile Gatso Scamera operators at the roadside, the camera backs up their corrobative evidence. (they made a note of the reg's as they went past) If argued they'd go back to the roadside & measure any identifying marks in the photo's & provide further evidence. The offence is that you were over it, not by how much. I got the impression on this unit the threshold was higher than normal for that reason. It was 40+ in a 30.

I got some very useful info from these guys.