The truth about Marksman LTI 20-20

The Opinion of an Expert Witness
based on field and lab testing of the Laser Gun

Click for more info in Hebrew
We do not condone excessive speeding, but we condemn
the methods and the manners, how the Israeli Police enforces speeding
abusing the lasergun, Marksman LTI 20-20 (L
aser Technology Inc. = LTI).

The LTI 20-20 is a small hand-held device that sends a laser beam to the targeted vehicle, registers it and calculates a speed and distance.
This is the main device utilized by the Israeli Police to issue speeding tickets, which are handed to a driver at the place of claimed offence.

However an Israeli expert witness contends that the reliability of a "measurement" using the Marksman LTI 20-20 is questionable, because it calculates the speed of the illuminated area on a selected target, instead of the actual speed of such a target.  The technical echelon of the Israeli Police does not understand this issue apparently.

The (Hebrew) Operator's Manual quite differs from the original (English) version written by LTI.  The Hebrew version claims that the software would EVER trap a faulty measurement.  However, following this superlative statement, another statement implies the truth.  The LTI 20-20 could provide an erroneous readings.  The expert has already demonstrated it's possible!
It means, an operator might not know whether a reading is faulty or whether a reading is reliable.

No one may guarantee a reliable measurement performed by an operator trained by the Israeli police.  This organization has overlooked the recommended procedure for optical alignment.

Three out of four equipment tested were found not aligned.  "Qualified" operators testified in Israeli courts, proving they had not been trained properly by the higher technical echlon.  Israeli courts had a priori believed the Police, but those days have gone apparently...  Now a few of these judges understand that The Marksman LTI 20-20 had been originally designed to measure distance and for this purpose it's quite reliable.

Israeli courts had (inter alia) based their previous opinions on the said "specifications" as written in the Hebrew Operator's Manual, which do not reflect the language and data as provided by the manufacturer.

The courts should understand that the Marksman LTI-20 may be reliably utilized only to measure the speed of a plain target the surface of which is perpendicular to the line of sight.  It should not be used to measure the speed of a three-dimensional target, the curvature of which is about the same size of the laser beam waist.

Herein two questions I have been asked frequently:

Q. "What is the degree of inaccuracy?"

A. It depends on the actual situation.
We have observed typical errors ranging from 2 to 8 MPH, but in unique cases large errors of 30MPH have been recorded!

Q. "Not being a scientist I do not understand too well why it is not accurate. I realize that there is a difference in the position of the target that is designed for.

A. The laser gun itself is a reliable piece of equipment and is quite accurate, in particular, when one attempts to measure the distance and the speed of a selected flat-surfaced target the area of which is perpendicular to the illuminating beam and the area of which is quite larger than the beam waist.

If the surface is not perpendicular to the line of sight then a "sliding effect" may occur.

Let's assume the target is stationary in reference to the laser-gun. Had the beam been swept accross the target the distance measured would be the average distance of the target and the speed calculated would be the change of this distance divided by the sampling time."

Israeli Police however deliberately ignores the above and abuses the Marksman to frame even innocent drivers. They couldn't care less!
In sum, the Israeli police abuses the Marksman LTI 20-20 for speeding enforcement.
The "aim and shot" technique (as they apply it) is improper!