Laser and the VA State Police

[SpeedySlowGuy]

Saw a VA state trooper using LIDAR for the first time last night.

Cruising south on I81 around 8pm...traffic was light, and I've seen plenty of patrols there, so I was keeping it to 5 over or so in the 65 zone. I've seen plenty of traffic going past troopers there at 80mph (its really wide open out there) and not get stopped, so I knew I wasn't in jeapordy.

Sure enough, as I approached a usual median break, I got a strident laser warning on the V1. Since I wasn't speeding, and even if I was, I was already toast, I didn't even let off, to avoid tipping off my V1.

He probably painted me from about 600-700 feet away.

Any VA police know how long you've been employing laser? Since 99% of drivers don't use detectors here, I've not witnessed a whole lot of instant-on technology being used out here. A little Ka instant here and there, but never laser. Didn't think VA wanted to make that expense.

Can we expect to see more of it? Sorry, I'm a tech junkie and find this stuff fascinating.

Just out of curiousity, what would you do if you lasered a car, and got some sort of interference that prevented you from getting a speed reading?

[Darin]

I don't have answers to your questions but was curious where in Va. this was?

[SpeedySlowGuy]

I 81 South of 66, north of New Market. Seen lots of VA staties and patrols in this area, north and southbound. There's a baracks in the Luray area I think, which is off the New Market exit. Haven't seen any patrols in the past year south of New Market. (Hope I'm not giving you guys any ideas ;))

That being said, I was instant Ka'ed by a trooper a few months back at 80mph or so on 81 just south of 66, and he didn't even bat an eye. Keep it 75mph and under and you should be fine. I usually do...unless I'm on the R6. That's a different story :D.

Now that I mention it, I do remember thinking I had heard that they had bought a LIDAR to experiment with.

Anyone else in the VA departments know the story?

[SpeedySlowGuy]

Saw another patrol at about the same mile marker, give or take ten miles, on the way back today.

Was using very low watt Ka, not laser. Don't *think* he was using instant....got faint signal, up until I was on top of him. Sitting in a large gap in the hill that is the median, so the gun was probably pointed right at the mound of earth in front of him. A lesser detector wouldn't have found this trap, but V1 did.

He was smart, waiting until people were right on top of him to get speed readings, not blasting signal down the highway for a mile at a clip. gdowkpc, I think he's been reading up on your tricks! :D

I was going the speed limit anyway; you might not believe me, but even when I'm not speeding I like having the detector. I'm a nerd for this sort of thing, and like knowing what's going on around me. It's funny...the girl behind me was obviously annoyed that I was only going ~70mph in the fast lane....until she saw the cop. Driving responsibly pays off for others too. I'm that guy who listens in on the pilot's conversation with the tower when they pipe it over the plane's intercom, rather than the in flight movie. I like learning about this stuff for intellectual curiousity, not cause I'm a crazed maniac looking to mow over a bus full of nuns at 90mph in my Hummer. :D

[vadep]

Originally posted by SpeedySlowGuy
Since 99% of drivers don't use detectors here, I've not witnessed a whole lot of instant-on technology being used out here.

That's because detectors are illegal in Virginia...

When I'm working traffic on an interstate (radar not LIDAR) I always "hold" until I find a suitable target... real easy to spot the detectors that way....

[SpeedySlowGuy]

Originally posted by vadep

When I'm working traffic on an interstate (radar not LIDAR) I always "hold" until I find a suitable target... real easy to spot the detectors that way....

Yeah, that's one thing I can say will get you busted...slamming on the brakes when the signal comes on. If you're speeding, you're speeding, and slamming the brakes won't save you. Brake dive is a dead give away, I'm sure...even if you don't have a detector, it shows acknowledgment of your guilt when you hit the brake hard when you see a patrolman. Even if he's not going to pull you in the first place, he will now I bet! I always resist the urge to pedal the brake when I see a speed patrol.

Vadep,
You or anyone in your unit have any experience with the Specter RDD?

[EricTheBald]

Actually, it's been my experience that a significant percentage of cops will go by what they see on their radar guns, not the fact that you slam on the brakes.


The most important thing to do when you get busted is to act right.

Cops are individuals so nothing is guaranteed, but in the majority of cases, when he first gets out of his car to come to your window, he has yet made an irrevocable decision to give you a ticket.

Turn off your car, take off your sunglasses, leave your seatbelt on, roll down your window, keep your hands on the wheel till he comes up to your window, don't make abrupt movements, tell him where your lic/reg/ins are before you reach for them, don't say anything stupid and don't insult his intelligence with some dumbass excuse.

You do those things and you stand a better than even chance of tipping his attitude back in your favor.

[vadep]

Well put Eric.

Personally speaking, I'm way more likely to cut you a break if you're honest. Every cop has heard every excuse, and that just generally irks me. The guy who says "Yeah, I was speeding. You got me, I'm sorry" is way more likely to drive away happy than the schmuck who tells me he has to pee.

[mcsap]

Or better yet... " I don't know why you pulled me over, I didn't do anything wrong ! "

[Hightower]

Originally posted by SpeedySlowGuy
Just out of curiousity, what would you do if you lasered a car, and got some sort of interference that prevented you from getting a speed reading?

I fail to see how that could happen. LIDAR measures your speed by measuring laser light. The only way to get interference with the LIDAR is to have an object block the laser light from going back to the LIDAR unit. I don't see how that could happen, and I have not yet seen it happen and we have been using LIDAR since 2000 I believe.

Hightower

[SpeedySlowGuy]

Originally posted by Hightower
I fail to see how that could happen. LIDAR measures your speed by measuring laser light. The only way to get interference with the LIDAR is to have an object block the laser light from going back to the LIDAR unit. I don't see how that could happen, and I have not yet seen it happen and we have been using LIDAR since 2000 I believe.

Hightower

Not quite correct from what I understand. It does get your speed by measuring laser light...but the idea isn't to prevent the light from going back to the gun (though that would work...a surface that absorbs, reflects or disperses the LIDAR light instead of sending it back to the gun would prevent you from getting a speed reading.).

The idea is that the laser gun works by timing the "flight time" of 70 or so pulses of light. In a matter of tenths of a second, the LIDAR sends 70 or so pulses of light. The first pulse takes so long to get to the surface and back...and each one successively shorter or longer periods of time, depending on whether the car is approaching or receding. By calculating the difference, the laser calculates the speed and distance of the target.

But by sending (instantly) a constant stream of light at the same wavelength that the laser is looking for, the gun can't see individual pulses and is "blinded".

You haven't seen it yet because not that many people want to spend $350+ to put a jamming device on their vehicle. But as more departments start using LIDAR, demand for that sort of device might increase.

[Hightower]

Yes, that may theoretically (sp?) work. But, If you are going to go the route of sending back light to "overwhelm" the LIDAR unit, I would think that you would have one hell of a time getting that to go back to the LIDAR unit. You would have to know where the LIDAR unit was at in order to aim your "jammer" right at it.

I don't really think the idea of the absorbing the laser would work either. In my training, we were told to aim at the license plate, or at night to aim at the headlight.

Most of the "Jammers" on the market are either illegal or do not work. That is for both Laser and Radar. Well, I guess they are actually all illegal in Minnesota.

Hightower

[SpeedySlowGuy]

Originally posted by Hightower
Yes, that may theoretically (sp?) work. But, If you are going to go the route of sending back light to "overwhelm" the LIDAR unit, I would think that you would have one hell of a time getting that to go back to the LIDAR unit. You would have to know where the LIDAR unit was at in order to aim your "jammer" right at it.


Hightower

Hey, we've got a parallel discussiong going on in the Parking Lots thread, so I won't dive into too many details, but Eric covered the larger point here.

You don't have to aim a Jamming device at the LIDAR, because it can't tell the difference between coherent 904nm wavelength light (laser) and incoherent (ambient, 'regular' non laser light). A very bright incoherent light sends light in EVERY direction, just like a lightbulb or the sun. No matter where the LIDAR is, it's sending light at that wavelength in that direction. Think of it like trying to see a flashlight held by someone in between you and the sun on a bright day, it's impossible.