Thread: Highway overpass shots don't have cosine error with LTI guns

1. Highway overpass shots don't have cosine error with LTI guns

Yes, it's true. Some of the ultralytes have a special feature that get rid of the cosine effect totally, so if you think you'll be safe by having those extra miles shaved off from a high angle overpass shot you're not with LTI guns.

How does it work?

First, the officer will plug in a distance reading into the gun. For example, if he was on a highway overpass he'd shoot at the ground directly below him. He plugs this number into the software and now the gun knows he's 20 feet above the ground, making the algorythm add miles to the original cosined speed.

Pretty cool huh if you're a police officer. Bad for us.

Highway overpass shots are a real threat. Unless your jammer has a curved lens on it it's highly unlikely it'll protect you.

JTW

2. Sure these aren't combining options in the survey mode vs the speed mode?

Checking my sources right now.....

-Suf Daddy

3. The cosine effect decreases as the range to the
target vehicle increases. At the maximum range of
the instrument, the vehicle is so far away that the
angle between it and the instrument is very small
indeed, and the instrument’s perception of the
target's speed is identical to its true speed. As the
vehicle approaches, however, the angle increases
until it becomes large enough to affect the
measurement.

To minimize the cosine effect, keep the angle small
by setting up the instrument as close to the road as
possible without creating safety risks, and target
down the road at ranges sufficient to keep the
angular difference small.

The following chart shows acceptable parameters
for minimizing the cosine effect. The chart indicates
the percentage of true speed measured, given the
distance from the roadway and the distance from the
target vehicle. To find a target's measured speed,
multiply the true speed by the number in the chart.

The diagonal created by the boldface numbers
indicates the boundary between acceptable and
unacceptable parameters. Numbers above the
diagonal are acceptable margins of error; numbers
below are unacceptable.
A good rule of thumb is not to exceed 10 feet off the
road for every 100 feet shooting down range to the
targets. If you want to target vehicles 500 feet down
the road, for example, set up no more than 50 feet
off the road.
Remember that the cosine effect is always in the
motorist's favor.

USING TIME OVER DISTANCE:

If you are measuring the distance with the
UltraLyte, make sure you are directly in line with
both targets.

4. What's the big deal? Anyone who wasn't sleeping through high school geometry and some that were could figure this out.

If the gun manufacturers had any class they would just add an inclinometer to the gun and let the processor use it's reading as an input to the speed calculation. I don't know why they didn't do this in the first place since they have been available and relatively cheap for a long time.

5. Grouping Sensors on a UL200

The UltraLyte 200 takes only those sensor readings
necessary to satisfy the current option. A feature is
available to manually “group” the sensors by taking
a separate reading with each sensor. Then by
scrolling to another option the instrument will
combine those readings to calculate other related
measurements.

For example, when slope distance is measured, the
range sensor is activated but the tilt sensor is not.
However, a horizontal or vertical distance
measurement requires readings from both sensors.
The straightforward way of measuring horizontal or
vertical distance is to simply shoot when the correct
indicator is showing so the instrument calculates
everything at once.

But suppose, for example, that an obstruction
prevents you from taking a reliable reading with one
sensor. In that case, you can use the “Group”
feature and shoot a slope distance measurement,
reposition the instrument, and then take an angle
measurement. Then scroll to horizontal or vertical
distance, and you will see that the instrument has
calculated a distance from your two separate sensor
readings.

To activate the Group feature, press and hold
Select/Edit until Grp appears on the screen. Next,
press Survey/Options to select your measurement
option. To turn the Group feature off, press and hold
Select/Edit again until you hear a beep and Grp
disappears. No data is sent out the serial port in
Group mode until the feature is turned off and the
beep is heard.

When using the Group feature, you may find it
helpful to first clear the sensors that you wish to
group by quick-pressing the Select/Edit button in the
desired menu.

6. Originally Posted by ronsc1985
What's the big deal? Anyone who wasn't sleeping through high school geometry and some that were could figure this out.

If the gun manufacturers had any class they would just add an inclinometer to the gun and let the processor use it's reading as an input to the speed calculation. I don't know why they didn't do this in the first place since they have been available and relatively cheap for a long time.
LTI is the first lidar gun I've seen to have this feature. I think it's only available on the new 100 w/DBC feature. Distance between car.

JTW

7. Survey Measurements
In any survey, there are four measurements to be
taken: slope distance, inclination, horizontal
distance, and vertical distance.

The UltraLyte 100 has no way to measure angles,
and takes only slope distance measurements.

The UltraLyte 200, however, has a tilt sensor that allows
it to measure inclination as well as slope distance.
From those two measurements, horizontal and
vertical distances can be calculated.

The triangle icon in the lower left corner of the
display screen indicates the measurement you are
taking. The icons are summarized in the following
table:

8. Distance between cars is mentioned but not available yet (as of a year ago etc.........)
-Suf Daddy

They on the street NOW?

Originally Posted by JTW

LTI is the first lidar gun I've seen to have this feature. I think it's only available on the new 100 w/DBC feature. Distance between car.

JTW

9. Originally Posted by Suf Daddy
Survey Measurements
In any survey, there are four measurements to be
taken: slope distance, inclination, horizontal
distance, and vertical distance.

The UltraLyte 100 has no way to measure angles,
and takes only slope distance measurements.

The UltraLyte 200, however, has a tilt sensor that allows
it to measure inclination as well as slope distance.
From those two measurements, horizontal and
vertical distances can be calculated.

The triangle icon in the lower left corner of the
display screen indicates the measurement you are
taking. The icons are summarized in the following
table:
Okay, well with what LTI said here it looks like all 100's, not just the ones with DBC have them.

My point of this thread was just to put more emphasis on this kind of jammer testing, since we're seeing alot of it.

10. JTW: I suggest the title of this thread to include "NEW" LTI guns.

-Suf Daddy gunning for accuracy.

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