Bear will know more about the specific model of the radar. Lidar makes a fairly small cone of light. Bear writes here:
hwybear wrote:I start observing vehicles about 1km away (through scope) monitor, then hit the vehicle with lidar around 700m. Then again around 550m. Then my final hit is around 500m-100m. This allows a visual observation, confirmed targetting history. The lidar beam is very concentrated being this close and any smog would be less than minimal affect.
The addition of moisture in the air reduces the effective range of the lidar. ie light rain might reduce my first reading from 700m down to 500m. Snow is just horrible and a waste of my time using a lidar. It is not affecting the accuracy of the readings, just how far away a vehicle can be targetted.
..........
At 100m
Lidar = 30cm beam width
Radar = 20 metres
There is absolutely never any doubt with lidar which vehicle is travelling what speed.
And, from wiki:
The use of many reflections and an averaging technique in the speed measurement process increase the integrity of the speed reading. Vehicles are usually equipped with a vertical registration plate that, when illuminated, causes a high integrity reflection to be returned to the LIDAR - despite the shape of the vehicle. In locations that do not require that a front or rear registration plate is fitted, headlamps and rear-reflectors provide almost ideal retro-reflective surfaces overcoming the reflections from uneven or non-compliant reflective surfaces thereby eliminating "sweep" error. It is these mechanisms which cause concern that LIDAR is somehow unreliable.
Most traffic LIDAR systems send out a stream of approximately 100 pulses over the span of three-tenths of a second. A "black box" proprietary statistical algorithm picks and chooses which progressively shorter reflections to retain from the pulses over the short fraction of a second.
Again, in your disclosure request you should ask for the manual, outlining the specifics of the unit, whether or not it was tested properly or not prior and after the shift, and you should also ask for the page(s) which lists technical limitation of the lidar.
In LEO's notes you should look for where the reading was taken, whether or not it is within the range of device, and whether or not he targeted your plate specifically. He might have confirmed your reading at a closer distance.
144 km/hr is 40 m/s, 135 is 37.5 m/s, 120 is 33.333 m/s, and 108 km/hr is 30 m/s. Speed limit is 100 where you were, right?
What were you really doing there, and what did you do next? Were you targeted at, say, 110 in 100, then speed limit drops to 70, and the cop wrote "110 in 70"?
For 600 m it would be 15 seconds at 144. Enough time for you to slow down.
Speeding tickets are some of the hardest to win. You need to exploit every technicality. What is the exact speed listed, and the exact fine?