Does ecilop radar have to have speed locked to issue ticket?

[bikaholic]

The legislation requires that a plate is retroreflective white, not flat white. Keep flat white for your coffees.

Just out of interest, car mounted speed cameras work on a different principle, being slant radar. Still doppler based, but not subject to cosine angle effect.

Odd that someone who doesn't speed much, intending to outlive his grandkids, would put so much effort into making his plate less reflective. I've put no effort at all into doing that, and still haven't had tickets. Simple really, no spid, no spidding tickets.

Same here, no speeding tickets ever, I put it down to the steelos rattling round inside my hubcaps. I just can't find any other reason.

[davereid]

Just out of interest, car mounted speed cameras work on a different principle, being slant radar. Still doppler based, but not subject to cosine angle effect.

All doppler radar suffers from cosine effect, especially slant radar.

[rastuscat]

All doppler radar suffers from cosine effect, especially slant radar.

Why 'especially'? The car mounted ones we started with were set at 22.5 degrees to the roadway, so the angle of incidence of vehicles as within a degree or two of that, unless they were driving at some bloody odd angle to the road. Certainly slant radar is subject to less cosine angle effect than a Hawk, Eagle, KR10, TR6, and Stalker. Even a laser is subject to cosine angle effect, and that's not doppler radar.

Anyway, it's a non-issue, as cosine angle effect always favours the motorist. That's physics.

http://www.radarguns.com/radar-and-cosine-effect.html

Ho hum.

[davereid]

Why 'especially'? The car mounted ones we started with were set at 22.5 degrees to the roadway, so the angle of incidence of vehicles as within a degree or two of that, unless they were driving at some bloody odd angle to the road. Certainly slant radar is subject to less cosine angle effect than a Hawk, Eagle, KR10, TR6, and Stalker. Even a laser is subject to cosine angle effect, and that's not doppler radar.

Anyway, it's a non-issue, as cosine angle effect always favours the motorist. That's physics.

http://www.radarguns.com/radar-and-cosine-effect.html

Ho hum.

No, its the other way around.

Imagine I am standing in the fast lane of an 8 lane highway, looking at Rastuscat riding towards me on his beemer, also in the fast lane.

He is traveling directly towards me - if I aim a laser or doppler radar at him, the speed I get is the speed he is traveling, right up until the point he runs me over.

But I don't want to get run over. So I move closer to the footpath. For each lane closer to the footpath that I get, Rastuscat will be observed more and more from an angle. So even though Rastus cat is still moving at the same speed, I will observe a slightly different speed.

In this case it is to Rastuscats favour, and as he gets closer to me it gets more in his favour, as I have to swing around to follow him.

In fact at the point he is passing me, he is still going the same speed, but he actually has no velocity toward me at all, and I will record a reading of 0.

When I stood in the middle of the lane looking at Rastuscat, my angle of incidence to him was 0 degrees.
The COS of 0 is 1. So I observed 100% of his speed.

When he was passing me I had swung around to follow his progress. He was now at 90 degrees to me. The COS of 90 degrees is 0, and I observed 0% of his speed.

This leads us to a discussion on "slant radar" as used in Camera Vans.

This is set up expecting to be at 22.5 degrees to the road way. So the manufacturer knows it will be reading around 92% of the actual vehicle speed.

So the speed recorded by the camera is obtained by observing the incident speed at this angle and increasing it by around 8% to determine the actual vehicle speed.

This is OK if the van is set up correctly, and the radar is at exactly 22.5% to the road. But if the radar is not slanted at this angle, then the speed camera will record the wrong speed.

If the camera is at an angle less than 22.5 degrees it will always exaggerate the speed of the vehicle.

Same as if a vehicle moves toward the left of the road as it passes the beam - changing lanes, or even a motorcycle being blown around in the wind.

Tell me Rastuscat - How carefully is the beam angle set up ? Are measurements made from the van to the road to ensure it is parked exactly parallel ? How is the beam angle set exactly ?

I was told that its not set. That its just been accepted that cosine effect always benefits the motorist.

[rastuscat]

No, its the other way around.

Imagine I am standing in the fast lane of an 8 lane highway, looking at Rastuscat riding towards me on his beemer, also in the fast lane.

He is traveling directly towards me - if I aim a laser or doppler radar at him, the speed I get is the speed he is traveling, right up until the point he runs me over.

But I don't want to get run over. So I move closer to the footpath. For each lane closer to the footpath that I get, Rastuscat will be observed more and more from an angle. So even though Rastus cat is still moving at the same speed, I will observe a slightly different speed.

In this case it is to Rastuscats favour, and as he gets closer to me it gets more in his favour, as I have to swing around to follow him.

In fact at the point he is passing me, he is still going the same speed, but he actually has no velocity toward me at all, and I will record a reading of 0.

When I stood in the middle of the lane looking at Rastuscat, my angle of incidence to him was 0 degrees.
The COS of 0 is 1. So I observed 100% of his speed.

When he was passing me I had swung around to follow his progress. He was now at 90 degrees to me. The COS of 90 degrees is 0, and I observed 0% of his speed.

This leads us to a discussion on "slant radar" as used in Camera Vans.

This is set up expecting to be at 22.5 degrees to the road way. So the manufacturer knows it will be reading around 92% of the actual vehicle speed.

So the speed recorded by the camera is obtained by observing the incident speed at this angle and increasing it by around 8% to determine the actual vehicle speed.

This is OK if the van is set up correctly, and the radar is at exactly 22.5% to the road. But if the radar is not slanted at this angle, then the speed camera will record the wrong speed.

If the camera is at an angle less than 22.5 degrees it will always exaggerate the speed of the vehicle.

Same as if a vehicle moves toward the left of the road as it passes the beam - changing lanes, or even a motorcycle being blown around in the wind.

Tell me Rastuscat - How carefully is the beam angle set up ? Are measurements made from the van to the road to ensure it is parked exactly parallel ? How is the beam angle set exactly ?

I was told that its not set. That its just been accepted that cosine effect always benefits the motorist.

We teach our munchkin Popos exactly what you have outlined re CAE (Cosine Angle Effect) then tell them not to worry about it, as it's always in favour or the motorist.

I did some speed camera work in 1993, when they were set up. A laser attached to the unit at a fixed, certified angle, was directed at a sight board placed the same distance from the kerbline as the camera, at least 10 metres back. Once sighted in, the camera was then at 22.5 degrees to the road, assuming that the kerbline runs parallel to the roadway. Quite a simple, basic arrangement. In fact, the camera having been set at 22.5, the electronics were programmed to allow for 23 degrees, compensating for any slight error in alignment, in favour of the driver.

Now, I haven't done it since 1993, so can't speak for how they are set up now. Please don't start jumping up and down about how todays practice is the same as back then, coz I don't know if it is.

How about we have a discussion on tracking history, not THERE is an under-rated issue.

[Bassmatt]

[QUOTE=rastuscat;1130257204

How about we have a discussion on tracking history, not THERE is an under-rated issue.[/QUOTE]

+1 not that I can contribute, but Im finding this all very interesting