so that is a good thing then lol If im going faster and hes at a sharpe angel thats his fault if the gun reads slower
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so that is a good thing then lol If im going faster and hes at a sharpe angel thats his fault if the gun reads slower
<scratching head>
These "tables" show a mathematical deviation from a "true" speed or velocity.
The difference in the recorded speed with an instrument at an angle is shown on these type of tables.
If you visualize an X and Y axis, you'll see that 90 degrees is no movement in one axis vs the other. In otherwords: the object never gets any closer to the instrument (towards it - or away) so the reading is "0" ALWAYS.
Its math.
The ISSUE with LIDAR goes a bit further than just cosine effect.
radar doesn't care about distance. Its all about the frequency shift, as witnessed by the Doppler effect.
LIDAR measures DISTANCES only. Its these distances where the measuring of speed on a moving object from the side of the road with LIDAR does the issue arise.
The above scenario of measuring a vehicle with LIDAR, from the side of the road (cosine influence like....) brings more than the probability of cosine influence (lowering the speed) but ADDS panning and sweep influence which can add to, or subtract from the calculated speed reading.
So after a radar operator is trained to run radar and dismiss cosine, because its in favor of the motorist, this LEO now runs LIDAR which because it measures distances, is now used in a situation (cosine: being off the side of the road several degrees) where the total influence on a LIDAR speed calculation can now NOT be in the motorist favor.
Yes, in certain circumstances, the readings can add to the calculated speed reading of a LIDAR gun.
all this from just the simple set up of traffic enforcement off the side of the road, (at an angle) to the direction of traffic.
CLASSIC. & no need to further complicate this by arguing refraction / bounce issues either.............
-Suf Daddy
Isn't that what the table tells us that when a vehicle traveling at 70mph will have "0" reading at 90 degrees? I may have misunderstood you. Here's a copy from the NHTSA manual. I presume they would not include this in the manual if it is not correct.Originally Posted by Suf Daddy
We're saying the same thing.
What I was trying to have people visualize is that mathematically any movement parallel to your aim yields a "0" reading because its 90 degrees.
Traffic coming directly towards you would be on your plane (X axis for example) and therefore 0 degrees.
The car will hit you unless you move just off its travel direction axis.
Two ways to visualize:
Graph paper [ GRID] or a linoleum floor with square "tiles"
Use the lines across and up and down (behind your stance) to figure this out.
Or
Pretend you are in an analog clock. You are standing in the center where the clock arms start.
Traffic coming towards you from 12 o'clock is on your "X axis" and if traffic was going across your point from 9 to 3 o'clock, there would be no speed in the X axis, just the traveling velocity in the Y axis (from 9 -3)
......or for the perfectionist would says you'll get run over with 9-3, make it 10 - 2
or
You stand at 5 th ave looking up some street towards 6th ave and you see a car going parallel to 5th ave along 6th.
You see it pass by you (on the unnamed bisecting street) and you look at the doors as the vehicle passes your plane / axis "X" or unnamed street, as it travels and a speed along 6th ave.
Because the 6th ave axis is a "Y" plane to your position, you see the doors pass by and then realize the car made NO speed towards you directly as it passed an intersection away. Hence the "0" speed to you and the LIDAR gun aimed up the no named street towards 6th ave.
On those charts / graphs parallel to your "y" axis is 90 degrees.
"0 degrees" is coming directly at you (as if you stood in the center on the street on the yellow line) and is the best "TRUE" way to determine speed, but you'll get run over..........
If you understand friction circles and the quadrants:
Left / Right
Accel / Decelerate
then you may get the idea too..........
Just different ways to look at this concept.
-Suf Daddy
Isn't that what the table tells us that when a vehicle traveling at 70mph will have "0" reading at 90 degrees? I may have misunderstood you. Here's a copy from the NHTSA manual. I presume they would not include this in the manual if it is not correct.
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