Lidatek LE-20 Laser Echo: Evening the Odds
Article and Photos by: Don Pavlik
and Neil McGarry

Neil and I visited Lidatek to see laser technology firsthand, talk tech of laser, install a LE-20 and do some in the field testing with Lidatek's available sampling of laser guns.

How's that driving record of yours? Clean? No tickets? How about your car insurance? Are you in that "low risk" group because of that clean driving record?  Let me guess... you never exceed the speed limit, right? Yea, that's what I thought. 

If you live in an area where law enforcement uses laser guns for speed detection the odds of keeping that clean record are stacked in favor of the police. (By the way, did I mention the insurance industry partially funded laser gun development? Tickets equal higher insurance premiums.) Lidatek is here to help even out those odds with the LE-20. 

Lidatek LE-20 

We all know there's an unspoken rule that the police won't bother you if you're a few miles over the limit--they've generally got their eye out for the guy who's not playing by the rules. But, that unspoken rule varies depending on where you live and the mood of the officer that you encounter. You could be outside that particular officers acceptable margin or perhaps the officer is just in a foul mood and you "look" like you need to be stopped--you never know! If you use a radar detector and the police are using a radar gun chances are you know he's up ahead and have time to lift off the throttle a bit just so you're sure not to attract any attention to yourself--let the woman in the Taurus riding in your blind spot get the attention as you drop back.

But today, with the increasing use of laser based speed detection that luxury of lifting off the throttle to be sure you're within the acceptable margin has been all but removed. It's even worse if he's playing "dirty pool" and hiding hoping to ambush unsuspecting drivers--then, you don't have a chance against laser. Even if you have a detector that senses laser, because of the way laser guns work, generally all your detector will tell you is that you've been targeted and by then it's too late. Before your brain has time to tell your foot to lift off the throttle the officer knows your speed. Game over.

Laser: the odds are against you 

The reason you have a fighting chance against radar guns is they spray a broad microwave beam at approaching traffic. That beam hits the traffic, some misses and shoots down the road, hits road signs and buildings--the microwave signal bounces all over the landscape. A radar detector picks up on the stray signals bouncing around and sounds a warning. If you have a good radar detector, under the right conditions, it can sense even the most evil radar, instant Ka, at ranges exceeding a mile away. 

Laser on the other hand, is a small tight controlled beam of infrared light. At the distance an officer is likely to target a vehicle the laser beam is no larger than the front of an average car. The laser light does not bounce around like a microwave beam so there's very little, if any, stray signal to pick up.

Lidatek's LE-20 is a solution to odds imbalance. The LE-20 is a small transponder that is mounted on the front of the vehicle, usually near the front license plate, that sits and watches for the laser light pulses that laser guns use to measure vehicle speed. When it detects laser it returns a laser pulse for a short period of time with a indium gallium arsenide laser (about 100x more powerful than LED based units!) giving you time to check your speed and respond very much like you would with a radar detector. 

The Science of No Speed

So how / why does this stuff work? Laser guns are very fast at obtaining a vehicles speed. Under the right conditions, a laser gun can get a speed reading in 1/3 of a second, but in real world use sometimes factors effect the guns ability to get a reading quickly. Simple factors like particulates in the air (remember we're dealing with light) or the officer not holding the gun steady can dramatically increase the time it takes to get a reading so it's not unusual for the laser gun to not get an immediate speed reading. Lidatek uses the real world delay to buy you some "stealth time" to check your speed and get into the speed margin.

The way a laser gun calculates a vehicle speed is by sending out short pulses of light (nanoseconds in duration) and watching for a return reflection of the beam from some reflective surface of the car (the license plate being the most desirable). Each time it sends/receives a pulse the gun calculates the distance to the vehicle based on the delay between the pulse and the time for the reflection to return. By taking lots of distance readings over a period of time the gun can calculate the speed of the vehicle. If the gun can't get repeated distance measurements that make sense it can't calculate the speed of the vehicle. In simple terms, the LE-20 varies the laser guns distance measurements. 

Laser emitter 
(not actual emitter, representative sample shown for security reasons)

When the LE-20 sees laser pulses that match the profile of a laser gun it samples the pulses for a short time (nanoseconds) to determine the gun type and to synchronize it's own laser pulses with the pulses from the laser gun, then it fires back. Laser guns watch for weak reflections of the transmitted pulse which is typically only about 10% of the light sent out by the laser gun. With the LE-20's laser synchronized, it sends out much stronger pulses back to the gun. Those pulses contain timing errors which result in distance calculation errors. With distance measurements that are all over the map the gun is unable to calculate vehicle speed. Also, the LE-20 is synchronized with the laser gun--and in most cases the gun does not detect that the reflection is not the original pulse. Instead, the gun just displays a targeting error code or a host of other obscure codes that the officer is likely to dismiss and simply move on to the next vehicle (the exception being the Stalker laser gun which sometimes displayed a code, no speed the remainder of the time).

The LE-20 operates for 5 seconds then shuts off. If the officer is persistent they will get a speed reading but by then you will have already slowed down and your law abiding speed will displayed. Suspicion from the officer is reduced thanks to this behavior. 

Sounds simple huh? Well, yes and no. For all this magic to work you must keep a few things in mind. 

First and most important, the laser gun and the LE-20 must be able to see each other. Laser guns look at the world with an extreme sense of tunnel vision so if the transponder is not in it's field of view it won't even see the laser beam. Luckily, at the targeting distance an officer is likely to use the laser gun beam is a rectangle (not a cone, contrary to belief) about the size of the front of the vehicle so chances are good the gun and transponder will see and be seen by each other. With laser detection, distance is your friend as it yields a fairly wide view for the laser gun!

Alignment and placement of the LE-20 transponder is critical. The LE-20 must be aligned so it's beam is parallel to the ground (a level is provided for this task) and pointing straight ahead from the cars centerline.  It's recommended that the LE-20 be placed near the front license plate. Officers are trained and conditioned to aim at the front license plate as it's the most reflective surface on the car (take a flash picture of a car at night and see what I mean), it's centrally located and easy to see at night. The handy thing about this is if you have a front plate the officer is probably going to continue to aim straight at the plate if he's having trouble getting a reading--it's his best target--all the while his gun is staring right in the face of an active laser. Having a front license plate on the front of your car is good insurance that the officer will target it. (front license plate haters crowd take note)

For larger vehicles such as SUVs, two transponders are recommended. Two transponders ensures that if the officer happens to target off center (perhaps aiming at a headlight) one of the LE-20 sensors is likely to see the laser gun. 

Installation and Testing

Installation of the LE-20 involves mounting the transponder along with some simple wiring for powering the unit, the connections for the warning LED, warning speaker and a power switch. The LE-20 kit includes an assortment of brackets, perforated bars, required screws, double-sided tape, wiring connectors and a bubble level for aiming the laser.

This installation was done on an Allroad and I have previously done an install on my S4. The best location for the transponder on the Allroad was in the middle of one of the Audi rings in the grill--this required the removal of one horizontal slats with a dremel tool but resulted in a very clean, stealth installation.

Each installation will most likely be unique so this will just cover the basics. You'll need to put your thinking cap on to determine the best location for mounting the transponder. Lidatek provides good information and guidelines so it shouldn't be too difficult for other vehicles. 

For the Allroad, use the supplied perforated bars and bend them into an upside down, squared off "J".  Mount the long end of the "J" to the back of the bumper support with industrial double-sided tape (use solvent or alcohol to ensure surfaces are clean) and hook the small end of the "J" around the auxiliary cooling fan support and secure with a screw. Be sure to put protection (plywood or something) in front of the A/C condenser before drilling... you don't want your drill bit slipping and puncturing your $500 A/C condenser coil! Mount the transponder to the bar with the supplied mounting hardware.

Allroad Installation

S4 Installation

For the wiring, remove the lower knee panel to gain access under the dashboard. The panel is secured with five 8mm hex bolts. Two at the bottom of the dash panel on either side, one behind the fuse panel cover and two behind the trim piece at the top of the steering column (remove the cover by pulling the top towards you and slightly upwards). Gently lower the panel and disconnect the diagnostic cable and the footwell light wires, then remove the panel . 

The cable for the transponder was routed across the fan support bracket, behind the headlight, along the side of the fender and through an available grommet in the firewall. The transponder cable plugs into a mating wiring harness for the inside wiring. The LE-20 requires a switched power source and  ground. Lidatek supplies an easy to follow wiring diagram to get everything hooked up.

Wiring Diagram

The warning speaker is very loud --it's recommended that you simply mount it up under the dashboard somewhere with the supplied velcro. Even in our well insulated Allroad test vehicle the warning could easily be heard. We opted not to install the LED. I have the LED on my S4 but the audible warning is much more useful.


With the LE-20 installed it was time to head off and do some testing to see how it performed. Tests were performed with the Stalker Laser gun. The tests were not done under controlled scientific guidelines but rather the way an officer would be likely to use a laser gun. 

The Allroad was equipped with a LE-20 and a Valentine One radar/laser detector to see if both devices were picking up on the laser gun. The vehicle was targeted at distances ranging from 500-1200 feet. Both the LE-20 and Valentine One detected each laser encounter. 

When the vehicle was targeted without the LE-20 in operation the laser gun displayed the vehicle speed and distance almost instantly in all cases. Having used the gun, it's obvious why and unprotected driver has no chance against laser--very fast speed calculation. 

With the LE-20 enabled, I was unable to get a speed reading during the 5 second period when the LE-20 was operating. The laser gun did display a distance reading but no speed and occasionally it displayed an E04 error code. At distances under 500 feet, I was occasionally able to get a speed reading depending where I aimed the laser gun. Bear in mind being targeted at ranges under 500 feet is probably not going to be a common occurrence as the officer is more likely to target vehicles at a distance--as mentioned earlier, distance is your friend.

Laser gun error code

Based on testing, the LE-20 does and excellent job giving the driver valuable time to check and adjust the vehicle speed if necessary.  From my own real world experience, I've been spared a visit by the "man in blue" twice by the LE-20 installed in my S4 . On both occasions my speed was waaay outside the acceptable margin when I was first targeted--without the LE-20 I'm certain I would have been stopped both times. For effective laser protection the LE-20 works!

I installed an LE-20 on my S4 last year. My initial conversations about it:
My install
My first experience with the LE-20

Contact Information:
12428 Hwy
99, Unit 51
Everett, WA