A Test of Two New Lidar Jammers

By Don Schroeder. Car & Driver, November 1996.

    It may not be very long before laser-based speed measurement, or lidar, becomes the speeder's No. 1 enemy. Lidar has been around for only five years, but there may be as many as 20,000 guns out there raising revenue through speeding citations. By the turn of this century, lidar guns may be selling at the same pace as radar guns.

    Lidar works by firing short pulses of laser light at a moving target and timing the return of the reflected light pulses. Unlike a radar beam, the laser beam is very narrow. At a 1000-foot distance, the working cross section of the beam is only four to six feet in diameter. So unlike radar, the lidar gun is aimed-usually by an officer at roadside-at a particular car. The latest lidar guns can measure and display a car's speed a third of a second after the trigger is pulled. Lidar detectors work well enough, but when one of them sounds the alarm, in most cases it's simply reporting to you that your car has just been successfully clocked by a cop.

    But lidar isn't flawless. There have been successful legal challenges, and the guns are vulnerable to jamming-even as they grow more powerful and sophisticated. In 1992, Car and Driver discovered the benefits of stealth-making a car less reflective and thus harder for lidar to find on the first trigger pull. In November 1993, our tests indicated that the effective range of the guns could be reduced by simply driving with high-beam headlamps turned on. Those headlights projected enough infrared rays to largely drown out the reflected laser pulses.

    Since lidar operates on a portion of the electromagnetic spectrum unregulated by the government, techno-nerds can dream up countermeasures without fear of prosecution. For example, since police are trained to aim at a car's highly reflective license plate, inventors quickly responded by covering those plates with translucent materials that absorb infrared light. Tests we performed in March 1996 found that some of these devices eliminated the reflective advantage of the license plates. The most effective license-plate obfuscator was the $50 T3 Alpha model.

    More inventions have emerged since that test. T3 Technologies (of plate-cover fame) has come out with Laser Vision. For $30, you get a pair of partial headlight covers made of a dark-colored plastic that attach with clear Velcro over the high-beam's bright spot. These allow lidar-confusing infrared rays to shine through while blocking much of the visible light, says the inventor, Scott Pember. The high-beams end up looking like daytime running lights. The covers pop off easily if the high-beams are needed at night.

    Another new laser jammer is the Laser Echo, made by Lidatek of Mukilteo, Washington. It returns a barrage of laser light the instant it detects an incoming zap from police lidar. Its transponder is the size of a pen and pencil set and has a tiny opening at its center through which it detects the lidar and fires its laser beam. The transponder is mounted at the front of your car and is connected by wire to an audio warning-a small squawking "annunciator" box-in the cabin. The Laser Echo system costs $290. You can increase your defensive firepower by adding one or two more of the laser units-at $250 each.

    Our tests were conducted on a provingground straightaway. Our targets were two cars with greatly varying capacities to reflect-a chrome-free, black, plasticnosed Pontiac Firebird and a Cadillac de Ville with a big, highly reflective chromed grille and exposed headlamps. The laser gun we used was the powerful LTI Marksman, although we ran some tests using an older, weaker Kustom Signals ProLaser as well. The gun was fired at approaching cars from a position 12 feet off the roadway. The cars approached at 50 mph, and we fired the guns at them at varying distances between 2600 and 400 feet.

    We chose this arrangement because police using lidar most often park their squad cars just off the roadway, set up their lidar guns, and fire at approaching motorists. Motorists are seldom clocked from behind because a cop car is easily noticed when passed. Also, the officer must drive faster and farther to overtake the speeder. The practical range of police lidar is between 1200 and 500 feet. Farther away, your car is a speck in the lidar gun's sight; closer in, you can probably see the squad car.

    It came as a surprise to us that some cars without reflective fronts-like our chromeless Firebird-are nearly unclockable by lidar if they're registered in one of the 19 states or seven Canadian provinces that do not require front license plates. This jet-black, pointy-nosed car with hidden headlamps was virtually unclockable by even the mighty Marksman, at any distance-evidence of the advantages of inherent stealth.

    But with a front license plate on that Firebird, the Marksman clocked it successfully from as far away as 2100 feetseven football fields. Adding a T3 Alpha cover over that plate reduced that successful clocking range to an impressive 400 feet. Problem solved.

    We wanted to test the T3 Laser Vision headlamp covers against the Marksman but quickly found that high-beams had no effect on that gun. We brought out the older ProLaser, put a front license plate on the Firebird, and watched the gun successfully clock its speed at 1000 feet. With the Firebird's naked high-beams on, the gun was only able to clock it at 500 feet. We then installed the T3 Laser Vision covers over the bright spots of the Firebird's headlights (near the headlamps' lower edges), and the ProLaser's effectiveness remained at 500 feet.

    Then we equipped the Firebird with the Laser Echo jammer, using its standard single transponder. We installed the device on a license-plate frame that comes with the jammer. The Marksman was unable to clock the Firebird at all, even with the front plate naked. But remember this-your invisible cloak lasts for exactly five seconds of squawking warnings, after which time the Echo jammer shuts down to prevent overheating of its internal laser. Five seconds of warning, though, is all the time in the world in this game. (We would like louder warnings-the Echo's squawker makes 76 dBA of noise.) Mission accomplished.

    The brassy Cadillac would not escape so easily. The Marksman was able to nail the speed of an approaching, completely unprotected de Ville from a vast half-mile away. Covering up that front plate reduced the gun's effectiveness to 1400 feet-not good enough. Using the Caddy's highbeams had no effect on the Marksman's effectiveness, rendering the Laser Vision strategy useless.

    Captioned as: Two Laser Echo transponders and a T3 Alpha plate cover were required to cloak Cadillac (above). The laser apertures required careful positioning, as well as a clear view ahead (left). Laser Vision covers (below) do block visible light. Experimentation revealed best position to be low on the headlamp.

    Captioned as: Two Laser Echo transponders and a T3 Alpha plate cover were required to cloak Cadillac (above). The laser apertures required careful positioning, as well as a clear view ahead (left). Laser Vision covers (below) do block visible light. Experimentation revealed best position to be low on the headlamp.

    Captioned as: Two Laser Echo transponders and a T3 Alpha plate cover were required to cloak Cadillac (above). The laser apertures required careful positioning, as well as a clear view ahead (left). Laser Vision covers (below) do block visible light. Experimentation revealed best position to be low on the headlamp.

    Time to go nuclear. We installed the Laser Echo (with one transponder) on the naked front plate. This strategy successfully jammed the older ProLaser gun. The Marksman gun was also stymied when it was aimed at the center of the car, but when we aimed at the Caddy's exposed headlights, the Marksman recorded its speed instantly.

    Then we tried two Echo jammers. We taped them on the grille, spaced well apart. This was getting expensive, but now the Marksman could nail the Cadillac's speed only if we aimed the gun at the Caddy's license plate. So we fitted a T3 Alpha plate cover, and finally, it worked-the Cadillac was invisible. Total cost: $570, or about four Ohio lidar tickets.

    The T3 Laser Vision headlamp covers seem to do what they advertise: They do dilute the bright light coming from your high-beams, and yes, the increased infrared of those high-beams can indeed confuse some lidar guns. But you'll need a friend standing far away to help you find the best placement on your headlightsand you'll need to find out who's using what on your stretch of highway, since a powerful gun like the Marksman renders this whole strategy ineffective. T3's Laser Vision covers may be helpful, but don't expect them to save you.

    The Laser Echo, on the other hand, does a terrific job of disarming lidar, but it comes with important caveats. The Echo's transponder must be carefully aimed straight ahead. If you don't use the plate frame, you'll need to find a secure place to mount the transponder where it will be well hidden yet not obscured by bodywork and trim. Much easier said than done. Also, our tests indicated that the lidar detector that turns on the Echo's defensive laser is only a third as sensitive as a Valentine One radar/lidar detector. If you have a highly visible car, you'll probably need more than one transponder to fully cloak it. One more thing: Don't ask us how, but the Marksman has a subtle way of notifying the cop that it has been jammed. It may be too subtle, but if the cop figures out you have one of these when you're pulled over, the jammer could conceivably be confiscated.

    If you drive in a state that requires a front license plate, at the very least buy a plate cover before you step up to anything trickier. By a narrow margin, the T3 Alpha cover is the best device of its kind we've tested so far, although other effective ones are available without the green tint. (See CID, March 1996.)

    We'll install a Laser Echo system on a long-term car to see how it holds up. But for now, this jammer earns our thumbs up.

    Captioned as: Where's the Lidar?