Radar & Laser / Lidar information Pages
More testing of the LTI Marksman 20/20
This week we go street sign hunting with the LTI
Basically, you can point this out the windshield and figure
your speed from highly reflective, large street signs.
While you could target cars around 1,000 feet, you'd have to be stopped
and resting the unit on the steering wheel or other stablizing method.
The hugest GREEN reflective sign I could find was 12 feet wide or more and maybe 10 feet tall.
On the downhill towards Exit 10 on I-93 N, I zapped the overhead sign
for 93/293 split and got its distance at 3696 feet.
Through the windshield (moving) I could get this for a distance / range reading.
Depressing the range / speed button would alternately give me the speed of my car.
I got out further North on 93 and lit up this sign at 9496 feet.
The sign moves.... LOL
This weekend I polluted
the interstate and local roads with Laser light from the LTI Marksman 20/20.
Since I'm getting used to this instrument I'm testing it the way your NOT
supposed to.
Large reflective signs
are not the targets police use to lidar you.
From INSIDE the car shooting through the windshield, ( a mentioned no no)
I targeted about 40 vehicles and could only get readings on about 7 of them at
around 700 feet plus.............
Again from INSIDE the car shooting through the windshield,
I shot countless road signs from the size of stop signs to the largest
Interstate Direction Signs they make.
The hugest sign I could find was 12 feet wide or more and maybe 10 feet tall.
REFLECTIVE green sign.
On the downhill towards Exit 10 on I-93 N, I zapped the overhead sign
for 93/293 split and got
its distance at 3696 feet.
Not bad for a 2500 feet rated lidar unit.
(I know its the specification for a car, and the NASA types have produced
25,000 feet returns off
really reflective targets.)
Backs of 18 wheeler trucks (white) like the Shaws Markets:
1364 and 1637 feet @ ~ 68 MPH
Chrome bumper Lincoln from behind, 1196 feet. 70 MPH.
Vehicle from behind thru windshield glass 1145 feet.
Trucks ~1300 feet
Cars ~1152 feet.......to ~800 feet on mostly level terrain.
Some large white vans and bucket trucks (aiming at the white bucket) yielded NO
readings.
I suspect beam scatter.
Curved shapes.
This interstate has these Mile Marker signs:
Click on the image to view it at
its original size
I was able to get a distance reading off these while driving, aiming through the
front windshield.
883 feet
855 feet
Doing this and pressing the range button will give me MY speed with some cosine
error.
Of course I never exceeded 65 MPH.
LAST test. During the dark of the evening 9: PM.
I pulled off the road, onto the shoulder to shoot some signs and the next few
Mile Marker (MM) signs.
The EXACT distances were
never measured.
Two returns (on the same presumed sign) were:
1882 feet with a speed of -1 MPH
and
1882 feet with a speed of -2 MPH.
The second measurement is
out the the specifications in the operator's manual.
Now these signs & fixed targets usually come back at 0 MPH.
However, two others, out of the 50 or so I shot, came back @ 1 MPH.
One large sign behind
the MM signs was shot and a distance of:
2,438 feet at 0 MPH came back
then at
2,440 feet at 0 MPH.
After driving to see if there were two signs within 2 feet of each other near
the 1/2 mile mark, I found none.
At about 3/4 mile I found a large street sign and a small 3" x 3" reflector next to it.
(IT should be noted that the 3" x 3" reflectors give readings at 300 feet with
the LTI and a similar
distance with the Osprey LIDAR range finder w/speed.)
So the conclusion is you can acquire targets through the windshield. cars at
about 800 - 1000 feet.
NO WAY Can they accurately follow the license plate ONLY.
FORGET IT.
Any officer who claims to be able to single out the plate only beyond 5-600 feet
is fooling themselves.
In a parked car, in day light, resting on the steering wheel I could at best
STRUGGLE
to keep the SMALL dot on
the back of the vehicle, let alone JUST the plate.
Sure I can; in my jiggling aim, cross the plate, time my trigger to zap the
plate for an instant,
but doing this on even a straight section of interstate requires a one off or my aim to be corrected
which further jiggles
the dot around the back of the vehicle, panning on and off the target several
times.
There's a reason these LTI units come with a shoulder stock.
There's a reason why Pro Laser III and the Stalker have them as "OPTIONS".
Make no doubt that with some effort and while outside the vehicle
the 200-300 foot range
is the best area to target an individual point on a vehicle.
The LTI Marksman will give you a "good" speed "locked" beep when they can't
acquire a speed reading or distance.
There will be an E -01,
E - 02 or E-03 displayed instead of a reading. No range or speed can be
displayed.
These readings either take some time or can be "one offed" to less than 1
second. There is no apparent reason why this happens.
However, several targets can be zapped one right after the other (bang, bang,
bang) but make no misconceptions:
The operator is just exercising their skills in being able to do this.
Speed surveying in this mode EXCLUDES the visual speed estimate
needed to determine a
tracking history of each vehicle individually.
Sure the scope allows the operator to visualize the vehicle while having a
peripheral view of the area,
but rapid target acquisition is JUST GUILT by association.......................association of proximity IMHO.