part 2
Realignment of Scope
Remove the elevation and wind age caps. Put the laser speed detector in target
mode.
With the laser rested on a solid support, sight a small target at least 700 feet
(230 Meters) away, by scanning the laser unit until you hear the “On Target”
(High Pitched Tone) both horizontally and vertically.
Sight through the scope and use the elevation and wind age adjustment screws
to move the red aiming dot to the same target.
~ To move the point of impact up, turn the elevation adjustment screw up and
down to adjust as needed.
~ To move the point of impact to the left, turn the wind age adjustment screw
left and right as needed.
Use the laser speed detector’s test mode to double check the new alignment.
Replace the elevation and wind age caps.
Scope Filter
The scope filter is the ring located on the front of the scope. By turning the filter
clockwise you can adjust the brightness and contrast for changes in lighting
conditions. The scope can be darkened for extremely bright conditions and
should be adjusted to allow maximum light when light conditions are poor.
During darkness, to eliminate the annoyance of light glare, the filter should be
adjusted to soften the view through the scope.
This gives the operator maximum versatility during extreme light conditions. Please note: The laser should never be aimed directly into the sun. Aiming the laser into the sun could melt the laser diode and could injure the operator’s site.
When adjusting the adjustment screw up, does this move the dot up or does it move the target up?
Brightness Contrast
The red dot used for sighting can be adjusted for intensity and size by adjusting the display control knob. By adjusting the red dot intensity and the scope filter, the optimal setting can be achieved to fulfill a variety of lighting requirements for speed and distance measurements, day or night. The operator will also notice that when the display intensity is reduced to lower levels, the display disappears before the scope’s red dot does.
~ Have the instructor/student adjust the red dot for size and intensity.
~ Choose your needs through individual adjustments.
~ When display intensity is reduced, remember your display will disappear before
the red dot.
V. Tests and Checks
The LTI 20-20 has been programmed to give the user the ability to test and check each aspect of the instrument that would have an effect on the accuracy and or the proper and efficient use of the instrument.
Test Incorporation
~ Self test
~ Display test
~ Scope alignment test
~ Calibration test
Self Test
When the instrument is initialized it puts itself through a self check. The instruments microcontroller interrogates each circuit board. If every thing tests positive the instruments display will form “8.8.8.8” to a blank display. If the instrument does not test positive, error 50-55 will be displayed. Double check your power source, if the power source is not the problem, contact a LTI 20-20 service center for assistance.
Display Test
To test that all segments of the display are functioning properly, press the “Test” button and keep it pressed. When this button is pressed, all segments of the display will light up with “8.8.8.8”. If any segments of the display are not functioning properly, a flaw will be evident in one of the numbers displayed. If there is a problem, the display will have to be replaced.
Scope Alignment Test
This test is designed to insure that the light beam of the laser is directed precisely where the red dot of the scope indicates. If the scope is out of alignment, the light beam will not hit the target vehicle and the patrolman will get an error message when trying to target any other vehicles. This test should be performed before each shift begins to insure proper and efficient use of the instrument. A detailed description of this test is provided in section IV. 1.
Calibration Test
Since the laser is not a radio frequency there is nothing in the instrument that can drift out of frequency. The speed calculations are referred to a crystal control time base which is guaranteed to have less than 100 parts per million (PPM) errors over the full operation temperature of the instrument. Yet, because it is necessary to verify, calibration has been incorporated into the instrument. It is suggested that the patrolman verify the calibration before starting a shift. There are several methods to accomplish this, three are listed below:
Fixed distance zero velocity check. In a convenient location establish a permanent known distance between two stationary points. For uniformity, the distance used should be 175 feet. If space is not available this distance is not an absolute requirement. To ensure the accuracy of the fixed distance, use a mental tape. The target should be a sign, pole, wall, or other permanent structure. On the target paint a bull’s eye or a mark to aim at. Measure 175 feet from the target and mark the designated point with an X painted on the pavement. This painted X is where the laser operator will always stand to test for verification of calibration. The orientation of the target surface should be perpendicular to the laser beam. To verify calibration a horizontal distance should be used. A slope distance, depending on the angle, will travel a longer distance. A distance measured to the base of a 30 foot light pole, of 175 feet is a measurement. The distance measured from the same point to the top of a 70 foot light pole, is a slope measurement, and would be 2.5 feet longer than a ground or horizontal measurement. Check laser accuracy by having the operator stand on the painted X and aim at the target. Pull the trigger and acquire the target. A 0 miles per hour speed measurement should be displayed. Pressing the speed 1 range button will switch to the range mode and will display the current distance, plus or minus one foot. There are two causes of the plus or minus one foot result. Holding the instrument at different locations, either in front of, or behind, the painted X and by the rounding of displayed ranges. A precise measurement is needed, carefully position the instrument over the painted X. By verifying the ranging and timing accuracy of the instrument with the above tests, the true elements used to measure velocity are checked. A 0 miles per hour speed measurement shows verification of the instrument timing accuracy. A 0 miles per hour reading of a stationary target is identical in nature to obtain accurate speed reading of a moving vehicle at all speeds. Therefore, calibration verification is complete.
Delta Distance Velocity Check
In a convenient location, establish permanent known. Distances between three points that form a line. For uniformity, and distances used should be 150 feet and 175 feet. If space is not available these distances are not absolute requirements.
Each time an LTI 20-20 us out of duty, they will go through the following test procedure:
A –
B – 8.8.8.8
C –
D – “t d 2”
E – 174 175 o 176
F – 1 MPH for every 6 inches
This test includes checks on the instrument ranging accuracy and on its timing accuracy which are the 2 elements that calculate velocity.
We know if distance and time clocks in the instrument are functioning properly then it will accurately measure velocity.
Confidence Check
10 degree round angle. Adjust red dot for size and intensity. Choose your own lighting requirements for your needs through individual adjustments.
When display intensity is reduced, your display will disappear before the red dot.
If something is wrong with the display, what procedures are required?
Main test suggested for verification of calibration.
Explain the methods of calibration that can be done in a moving vehicle.
Set Up Preparations
Clear line.
Setting up to minimize angular or cosine effect.
Set up so that the instrument is shooting out of or through a side window other than a wind shield.
Line of Sight
0.3 seconds.
Angular – Cosine Coincide
Name three items that should always be considered in setting up for use of the LTI 20-20.
Why should you avoid using laser through a wind shield?
If shooting through a window, what procedure is suggested?
Is the angular effect on a laser the same or different from radar?
Setup so the laser is as close to the road as possible.
How do you know when the instrument has acquired a reading?
How can multiple readings be acquired?
What hard ware and soft ware has been incorporated into the instrument that makes it very difficult to produce an error free reading?
E 1
E 2
E 3
E4
E 50-55
If vehicle is out of range, it makes a buzzing noise.
Keep trigger pulled.
As soon as the vehicle comes into range the LTI 20-20 will produce a reading.
For the laser to measure distance, it is necessary that the section of read between the two reference points to be straight.
Operational Sequence – Method One
Press the timing mode button.
Sight the laser.
Press the timing mode button.
Press it again.
Method Two
This form of speed, takes an average speed of the vehicle over a distance, not the peak speed.
The larger the object, the longer the range.
Ranging Differences
Brightness of color
Finish – Shiny vs. Dull
Mass
Shape
Angle orientation
What are the characteristics of a target that will affect the maximum range of the LTI 20-20?
Why is the car further away?
What is the range accuracy of the LTI 20-20?
Maintenance
What is the proper procedure to take, if the LTI 20-20 gets wet?
Is it necessary to clean the unit before it is stored?
How should you clean the front lens? (Carefully)
