Laser Jammer Test from the Rear

[anjoem]

Hi guys,

Please would someone test the effectiveness of the various available jammers from the rear. Also when this test is performed, ensure that the gun is aimed at least 20 degrees to the vehicle. Most of your tests are straight in front, we have yet to test these jammers from an angle.

Would be really interesting to know the results?

Anyone willing to take it on?

Anjoem

[jimbonzzz]

Hi guys,

Please would someone test the effectiveness of the various available jammers from the rear. Also when this test is performed, ensure that the gun is aimed at least 20 degrees to the vehicle. Most of your tests are straight in front, we have yet to test these jammers from an angle.

Would be really interesting to know the results?

Anyone willing to take it on?

Anjoem

We might try it at a future Guys of LIDAR test.
The problem with laser from the rear, is that in almost all cases the officer first targets you at close range, so in many circumstances with the current jammers available it is very easy to obtain a speed reading targeting this way.

Jim

[Carlos from Spain]

I would also like to see such a test, as this is the way they tipically target you here as well.

Even though thet jammers won't be able to jam at such close range as when the car is right beside the laser when just overtaking it, the laser itself will not be pointing at the car in that moment since the laser has to be somewhat paralel to the direction of the car in order to avoid the cosine error (the greater the angle with the direction of the vehicle, the greater the difference of the reading of the laser to the real speed of the vehicle, in favbor of the driver, since the speed read by the laser is proportionally less than then real speed). When you target a car from the rear you are beside the road so you cannot traget the car when its passing right next to you since you would be targeting the vehicle perpendicualr to the direction and the laser reading will not work.

So typically, when they set the laser to target your rear, they are beside the road (otherwise they would get run over) and target the car at no more than a 20º or so degree angle, so by the time the car is in the "view" of the laser beam, it will probably be at least over 120 feet away form the laser. So as long as the jammer can jam from past 120 feet onwards, it will probably do the job. It doesn't need to jam from 0 to 120 feet since the laser gun will not be targeting the rear of the vehicle yet at that proximity.

The other scenario they use for rear targeting with laser is from an overhead bridge. In this case they can position themselves right on the path of the vehicle, but since they are shooting from overhead, they have to again wait till the car is over 100 feet away in order to get a correct reading. They cannot shoot straight down since the laser will not read, again due to the conie effect.

So it would be great to see such a test; overhead and side of the road, rear targeting at a range between 100 feet and 350 feet (typical rear photo-lidar). Also it would be important to test in tripod mode, since this is more dificult to jam than hand-held and its how photo-lidar is always employed, and is the worst case scenario of the two.


... Guys of LIDAR to the rescue? :wink: :D

[anjoem]

i agree, just that at one overpass they are way more than 20 degrees from the vehicle, i'll see if i can get a pic, then i'll post it here.