Slip Factor Test

[ThE_JOkeR]

I posted this up momments ago....
Wow! Watch this on laser guns!

and I was wondering next time you all get together or if any of you could do some testing on "Slip Factor". I'm highly interested in how easy you all find it to cause these currently used in the states LIDAR Guns to get readings that are inaccurate.
Such as if the officer was standing off to the side of the road and could see the side of your car from a front angle.
Ofcourse there has to be 1 control gun that does not move & 1 that is being panned across while the vehicle is moving presumably on cruise control.

Have you guys ever thought about this and do you guys have any interest in such a test?



ThE JoKER

[jimbonzzz]

Although it is interesting, that isn't really what we do. But, I also won't say it will never happen. This is something that Suf Daddy has been gathering information on for a while, so if comes to one of the GOL tests I'm sure he would want to do some experimenting with the different guns.

[ThE_JOkeR]

Originally Posted by jimbonzzz

Although it is interesting, that isn't really what we do. But, I also won't say it will never happen. This is something that Suf Daddy has been gathering information on for a while, so if comes to one of the GOL tests I'm sure he would want to do some experimenting with the different guns.

Yeah, cool np. I understand. Perhaps an article of Suf Daddy's collective information if he wishes too extend his knowledge out to the community.

If not, I'm grateful for the test you do.
Keep up the great work!

[Suf Daddy]

The other thread seems to be OT with UK fines........

I really think somebody missed a gem buried in that thread.

So I say again:

"Youtube

The truth about LIDAR"
(all run together)

While its amature video, its the tip of the LIDAR iceberg.

-Suf

[Suf Daddy]

<jok3r>

Here it is in a quick nut shell:

You really should Search the archives & threads.

LIDAR is purely a range finder.
It "calculates" a speed reading.

The issues are:

MOST LIDAR operators have a radar background.
This school of thought is that cosine** error is in the favor of the motorist.

RE: straight line velocity, this IS true. an degree off axis of velocity direction is a mathematical calculation to how much LOWER a speed reading is.
Kinda a reference point thing.

Now carry that over to vehicles using LIDAR.

Once the operator stands off axis (median/shoulder/BDL) to clock traffic, using his/her "range finder" the view of the vehcile to the LIDAR light is now opened up to include the side of the vehicle.
This may increase or decrease the distances the return pulses carry to the LIDAR Rx for processing (least squares*) USED to calculate a speed reading.

THAT's where the influences / errors affect a speed reading.

Mathematically, every 4 feet in a linear graph, is ~2.7 MPH (for 60 MPH being 88 feet per sec)

So not only is the LIDAR beam 3" square @ 1,000 feet.

The front to back (hood to roof) and vice versa, coupled with the side pan or sweep "influences" are probable to effect the speed reading calculation.

ENHANCE this with the operator instructions (which *may* objectively, seem to attempt to combat this) to aim at one point AND FOLLOW IT during clocking. <<< this guarantees a "pan" to the aiming operation >>>
A license plate for example.

Now all this is WITHIN the "external" environment reflections, when swept by the operator, could, under certain instances lead to readings directly related to the motions of the operator aim solely.
Examples are sign posts, reflectors, objects, guardrails..........any reflective/refractive object.

The videos I reference above show this.
and ONLY because the -video- distances are shorter, is this easy to reproduce consistently.

Since distance isn't really a factor in a LIDAR gun determining a speed, because LEOs use them beyond 1,000 feet, its a real issue and nearly every reading will be influenced and possibly "calculated" wrong.

Caveat Emptor.

-Suf

* (least squares)
raw data returns graph similar to this way even though school info is COMPLETELY different than speed processing of data (pulse) returns.
-------------------------------------------------------------------------------------------------------------------------------


** Cosine error graph (poor one I'll admit, credit: http://www.jesbeard.com/figure5.gif)


MPH operator manual has the BEST cosine graph period. IMHO.

But I can never find it on the intarw3b.
-Suf

[ThE_JOkeR]

Thanks for the reply. Yeah you didn't have to write all that I would of searched, I just forgot. I'll check out that video.

[o2bad455]

I beat a Lidar ticket about 10 yrs ago in CT by arguing panning error. I actually threw out several different theories, but that was the one that the Judge found persuasive. Lidar seemed to drop out of favor in that area after that, and I never saw it used again in that spot (or on that highway, come to think of it).

[ThE_JOkeR]

I looked at those videos you mentioned & they were just panning on the ground.
According to LTI the radar detector is smart enough to know when its measuring something movable & eliminates panning errors etc within 1mph.
Which is my real area of interest. Real world scenarios because frankly our cars are not the ground.

Got a question....

When using the LIDAR gun is the person suppose to pinpoint a spot and follow it precisely or fire it @ a spot and not move it at all(as in not follow the pinpointed spot) ??

[Suf Daddy]

Lettme ask you this:

Why you want me to help you?

-Suf

Stalker claims 8 MPH error trapping software, we can see that's not exactly the result one can get.
Now you "spec" LTI for 1 MPH......

You listening to me?

Originally Posted by ThE_JOkeR

I looked at those videos you mentioned & they were just panning on the ground.
<snip>

[ThE_JOkeR]

Originally Posted by Suf Daddy

Lettme ask you this:

Why you want me to help you?

In all honesty I am just curious. I just wanted to learn.

Originally Posted by Suf Daddy

Lettme ask you this:

Stalker claims 8 MPH error trapping software, we can see that's not exactly the result one can get.
Now you "spec" LTI for 1 MPH......

You listening to me?

Yes, sir!
ok... I quoted the LTI 1mph from the British video where they were talking with someone of TeleTrafficUk. Which I believe is the UK manufacture for the LTI.

Now why I say those videos just show them shooting at the ground is because in the video they said..
"The UK Manufacture of the LTI 20-20 REJECTS the possibility of getting misleading readings FROM MOVING VEHICLES"

Then she says to the TeleTrafficUK representative "You accept can get a speed reading from a stationary vehicle"
TTUK Rep - "Oh Yes..........",
She says "but what you're saying when that vehicle is moving, the laser gun does what?"
Rep - "It Traps out Any Panning Errors." ..................
She - "We didn't get an error reading, we got a reading of 4mph"
Rep - "yes you would against a stationary target...."
She - "You're saying that could't happen against a moving target"
Rep - That's Exactly Right..."
She - "but a ready of 2mph could happen on a moving target"
Rep - " I think thats highly unlikely, 1 MPH if at all, but anyways thats well within tolerances"

Thats why I point out those videos are only panning across the ground & a non-moving target. Because the Rep stated the software works against Moving Targets, not Stationary targets.

Understand what I'm getting at?