Range on camera vans

[jith]

agtlaw said:

surveyor_101 said:

depends slightly on the device in use. the LTI 20/20 is a common one and they work at 600m easy, I believe some work at half a mile.

Depends on the vehicle type van/car and speed over.

Slightly?

LTI 20/20 TS/M Speedscope - 999.9 metres.
LTI 20/20 Ultralyte 100 - 610 metres
LTI 20/20 Ultralyte 1000 - 1000 metres
LTI 20/20 TruSpeed DC Laser - 750 metres
LTI 20/20 TruCAM - 1200 meters

I think it might be an idea agt, to state that these are the manufacturers claims; and that's if they are actually functioning properly. (Cue kinkybootreeltoreel any second now!)

J

[jm doc]

jith said:

agtlaw said:

surveyor_101 said:

depends slightly on the device in use. the LTI 20/20 is a common one and they work at 600m easy, I believe some work at half a mile.

Depends on the vehicle type van/car and speed over.

Slightly?

LTI 20/20 TS/M Speedscope - 999.9 metres.
LTI 20/20 Ultralyte 100 - 610 metres
LTI 20/20 Ultralyte 1000 - 1000 metres
LTI 20/20 TruSpeed DC Laser - 750 metres
LTI 20/20 TruCAM - 1200 meters

I think it might be an idea agt, to state that these are the manufacturers claims; and that's if they are actually functioning properly. (Cue kinkybootreeltoreel any second now!)

J

And to claim that there is no significant "slip" or movement of the beam across a vehicle at these ranges is complete nonsense

[HantsRat]

jm doc said:

And to claim that there is no significant "slip" or movement of the beam across a vehicle at these ranges is complete nonsense

I can get slip reading from a flat wall which states its travelling at 1 mph. I however need to move the laser quite dramatically to get this result and covers a large proportion of the wall. When head on facing a car you can't move the distance necessary to get a slip reading. Even if you did it would be about 1mph.

Don't reply with that video on Youtube showing slip errors. They were targeting vehicles side on which we simply don't do.

[covboy]

HantsRat said:

I can get slip reading from a flat wall which states its travelling at 1 mph. I however need to move the laser quite dramatically to get this result and covers a large proportion of the wall. When head on facing a car you can't move the distance necessary to get a slip reading. Even if you did it would be about 1mph.

Don't reply with that video on Youtube showing slip errors. They were targeting vehicles side on which we simply don't do.

How do you hold a gun steady enough to get a reading at 600+ Metres. The angle must be minute to pick up (say) a number plate at about 450mm wide ?

[FurtiveFreddy]

covboy said:

How do you hold a gun steady enough to get a reading at 600+ Metres. The angle must be minute to pick up (say) a number plate at about 450mm wide ?

Haven't you read my post above? The beam is about 2m wide when it reaches the number plate. They're not trying to get a 2mm spot on it.

As long as the red dot in the scope is somewhere on the front of the vehicle it's good enough to get a reflection from the plate or headlights.

[covboy]

FurtiveFreddy said:

Haven't you read my post above? The beam is about 2m wide when it reaches the number plate. They're not trying to get a 2mm spot on it.

As long as the red dot in the scope is somewhere on the front of the vehicle it's good enough to get a reflection from the plate or headlights.

OK - Simple triganometry. Distance 600 metres Beam width (generous) 4 metres Whats the included angle ?

[Sheepshanks]

agtlaw said:

LTI 20/20 TS/M Speedscope - 999.9 metres.
LTI 20/20 Ultralyte 100 - 610 metres
LTI 20/20 Ultralyte 1000 - 1000 metres
LTI 20/20 TruSpeed DC Laser - 750 metres
LTI 20/20 TruCAM - 1200 meters

Interesting. I don't know what all the different models are but I was done by a tripod mounted unit on a bridge over motorway standard A road. Some enquiries revealed they could speed check at 1000 metres.

I did see on of the Police programmes they were using the same set-up at a very long distance to check speed but they couldn't get the reg that far out, so they were following the car and taking another pic with the reg more visible.

[GC8]

thescamper said:

Not sure that gravity or wind will affect a laser.

Einstein has an opinion about the former. Wind, not so much...

[Bigyoke]

Marvtec said:

I'd like to know where there's a 4 mile straight...

Dropped pin
near 266 Seven Mile Straight, Crumlin BT29 4YT
https://goo.gl/maps/GiJ1tYdPPxP2

[FurtiveFreddy]

covboy said:

OK - Simple triganometry. Distance 600 metres Beam width (generous) 4 metres Whats the included angle ?

You're over-complicating it.

Imagine you're trying to get a photo of a car 700m away with a camera fitted with a telephoto lens. It's no harder than that.

[Silverage]

Just to close this one out, today is the 14th day after I spotted the camera van. I have not received anything in the post from the camera partnership, so if I did happen to be exceeding the limit, I must have been out of range.

[karona]

I requested to see the video when I was tagged at 65 mph on the Standing Stane Road near Kirkcaldy, (in a van) They showed me a vague orange blob in the distance, several hundred metres away, with a digital screen readout in the same frame showing range and speed. It also showed another car between me and the camera.
They played the video forward until I was 50 or so metres away, with a clearly readable number plate. The digital readout at that time showed a lower speed. The images supplied to me with the NIP showed the close image, (yes, I was driving) with the far image's digital readout edited into the frame.
I kicked up a fuss there and then about 'photoshopped' evidence, and the possible interference with the other car, and got a letter a week later saying "No further action".

[Silverage]

karona said:

I requested to see the video when I was tagged at 65 mph on the Standing Stane Road near Kirkcaldy, (in a van) They showed me a vague orange blob in the distance, several hundred metres away, with a digital screen readout in the same frame showing range and speed. It also showed another car between me and the camera.
They played the video forward until I was 50 or so metres away, with a clearly readable number plate. The digital readout at that time showed a lower speed. The images supplied to me with the NIP showed the close image, (yes, I was driving) with the far image's digital readout edited into the frame.
I kicked up a fuss there and then about 'photoshopped' evidence, and the possible interference with the other car, and got a letter a week later saying "No further action".

Interesting. Do you remember what range was shown when you were just a blob?

[V8Matthew]

DELETED: Comment made by a member who's account has been deleted.

Camera vans are manned by volunteers, at least where I live. The police don't need cuts, they need a massive paperwork cull. AFAIK making an arrest can take up the better part of a shift due to excessive paperwork/procedure. It has been known for some stations to end up with one officer left on response.

[covboy]

V8Matthew said:

Camera vans are manned by volunteers, at least where I live.

Really ? Wheres that ?

[karona]

Silverage said:

Interesting. Do you remember what range was shown when you were just a blob?

[spud989]

caelite said:

Marvtec said:

I'd like to know where there's a 4 mile straight...

There are a couple of really long stretches around Stirling on the A811. They must be close to 4 miles, there is almost always a camera van skulking about on them too. Had some close calls sighting vans after multi-car overtakes when I used to commute through that way. Straight, flat road as far as the eye can see and there are still folks doing 45

It's not absolutely dead straight, but for all intents and purposes it is:

https://www.google.co.uk/maps/dir/53.5778805,-0.93...

5 miles, part of my journey to work. Very quiet at night . Never a camera on that part of the M180. There are camera spots closer to Shorpe, though.

[spookly]

FurtiveFreddy said:

covboy said:

OK - Simple triganometry. Distance 600 metres Beam width (generous) 4 metres Whats the included angle ?

You're over-complicating it.

Imagine you're trying to get a photo of a car 700m away with a camera fitted with a telephoto lens. It's no harder than that.

It isn't really overcomplicating it at all.

At that distance the beam width, is greater than the width of the car and risks picking up returns from something other than the car being targeted. If you assume the beam width is less than the width of the car, then they'd need to maintain the angle +/- 0.5 degree to have any confidence it hasn't slipped onto something else. That's before you take into account potentially reflective things below the vehicle which could also produce a return, such as metallic road debris or reflective markings on the road.

What is most troublesome about these cameras though is that the 'evidence' they produce does not do anything other than show a measurement. The frames and video they produce do not prove that the beam and targeting are aligned, only what the operator thinks the beam is pointing at. Even if they are correctly aligned, it does not show the beam spread or pattern and what it might have hit and when.

[FurtiveFreddy]

spookly said:

It isn't really overcomplicating it at all.

At that distance the beam width, is greater than the width of the car and risks picking up returns from something other than the car being targeted. If you assume the beam width is less than the width of the car, then they'd need to maintain the angle +/- 0.5 degree to have any confidence it hasn't slipped onto something else. That's before you take into account potentially reflective things below the vehicle which could also produce a return, such as metallic road debris or reflective markings on the road.

What is most troublesome about these cameras though is that the 'evidence' they produce does not do anything other than show a measurement. The frames and video they produce do not prove that the beam and targeting are aligned, only what the operator thinks the beam is pointing at. Even if they are correctly aligned, it does not show the beam spread or pattern and what it might have hit and when.

Hence why you should request photographic evidence as someone did a few posts back and challenge it if there's any doubt. Don't get me wrong, I'm not exactly a fan of this technology, but in good conditions when there's only one vehicle in the operator's field of view, it's not difficult to get an accurate reading contrary to what some others here seem to think.

Only the driver knows whether the reading is accurate or not, as they can see their own speedometer. If you are the driver and you know what speed you are doing when pinged and it's a long way from the number on the NIP , then you should challenge it.

[Davidonly]

spookly said:

FurtiveFreddy said:

covboy said:

OK - Simple triganometry. Distance 600 metres Beam width (generous) 4 metres Whats the included angle ?

You're over-complicating it.

Imagine you're trying to get a photo of a car 700m away with a camera fitted with a telephoto lens. It's no harder than that.

It isn't really overcomplicating it at all.

At that distance the beam width, is greater than the width of the car and risks picking up returns from something other than the car being targeted. If you assume the beam width is less than the width of the car, then they'd need to maintain the angle +/- 0.5 degree to have any confidence it hasn't slipped onto something else. That's before you take into account potentially reflective things below the vehicle which could also produce a return, such as metallic road debris or reflective markings on the road.

What is most troublesome about these cameras though is that the 'evidence' they produce does not do anything other than show a measurement. The frames and video they produce do not prove that the beam and targeting are aligned, only what the operator thinks the beam is pointing at. Even if they are correctly aligned, it does not show the beam spread or pattern and what it might have hit and when.

Totally this as above! These things are riddled with potential sources of error. So error codes must be triggered all the time (meaning intelligent use of a garage door opener ought to be low-risk). However all the software compensation built in to address these (known and serious) weaknesses is far from infallible even operating in perfect conditions.

They certainly should not be used more than 250 meters away and the fact they can produce 'evidence' at all is a scandal. The beam spread is massive, the potential for reflections off other objects (spokes of a wheel, a road sign?) or misalignment and hitting another car is huge. The alignment check and a recent post about doctored photographic evidence makes these very flaky in my view.