LIDAR Saturation

bhaubrich · #1 (**permalink**) 2008-12-10

Can direct sunlight or sun-glint (refelected sunlight) from a vehicle affect the measurements taken by police radar and possibly cause inaccurate readings?

TSi+WRX · #2 (**permalink**) 2008-12-10

^ You asked for LIDAR in the title, but said RADAR in your post.

In terms of LIDAR, yes, it's possible - I think that it's more possible in a "situational" sense, as the glare may cause the enforcer enough discomfort that he/she could accidentally induce a panning error.

Bright, oncoming/incoming, light, such as HIDs and even standard halogen incandescent DRLs, have also caused various LIDAR devices to throw up error as well as spurious jam-codes.

Overall, however, in the situation that you've painted, I believe it is one that's going to actually FAVOR the LIDAR/enforcer. Bright ambient conditions tend to drastically decrease the effectiveness of active jammer devices (both LED and laser-diode based, alike). And in the situation that you've set up, it would stand to reason that the sun is "behind" the enforcer (in some manner, silhouetting him), which will make the jammer's job much harder.

The Osijek test by the European SpeedLab hobbyist group showed just how unfavorable such conditions were. You'll see, from their data, that even the vaulted Laser Interceptor suffered PTs that were larger than anticipated, once the sun was a factor that was not in its favor.

Veil Guy · #3 (**permalink**) 2008-12-10

I suppose in your post you actually meant affect police lidar (laser) and not radar.

Yes. Reflected sunlight does affect police lidar, but not in the way you are hoping, I am afraid.

What is the most likely outcome is that in these particular circumstances the effective range of police lidar is reduced. Police lasers employ something called AGC (automatic gain control) which automatically adjusts the police laser guns on sensitivity.

If you think of a police laser gun as a camera with automatic exposure compensation settings, you'll get the idea. When you take a picture of someone while facing direct sunlight, your camera will adjust its exposure to properly expose the backgound, but all too often the individual is underexposed. The same kind of phenomenon happens with police laser.

I have targeted highly reflective vehicles while the sun was behind me and low in the sky and have found the in certain circumstances the range of police laser can be reduced by as much as 50% just by the angles. When the angles change sufficiently enough where the reflection goes away, the range increases again.

Police laser also use pretty sophisticated algorithms to accurately calculate your speed and if something like excessive direct or reflected sunlight adversely affected the lidar gun, error codes could also be the result, but not invalid speed readings.

I believe that, in general, these kinds of lighting conditions, will tend to always favor the driver and not the lidar operator.

Veil Guy

bhaubrich · #4 (**permalink**) 2008-12-10

OK Guys, Yes I mean LIDAR. I believe that the officer in my circumstance was attempting to target my vehicle with the sun behind me (target vehicle) and the officer. I took a photo shortly after the citation was issued showing the bright sunlight. I will try to post the photo a little later. I believe that the laser detector on the officers LIDAR gun may have been saturated by direct sunlight causing an erroneous error. Is this possible or even probable in your opinion? Thanks for your help. Best Regards, Brad

Veil Guy · #5 (**permalink**) 2008-12-10

bhaubrich,

Sorry, but I am not inclined to believe that such a circumstance could ever generate a higher speed reading being indicated on the officer's lidar gun.

Veil Guy