Lidar Enters the Radar Wars

By Don Schroeder. Car & Driver, April 1994.

    It was just eighteen months ago that Car and Driver tested and evaluated five of the best radar detectors offered for sale in this country. The tests were exhaustive, and for us, exhausting. We tested the sensitivity of these detectors to X-band and K-bank radar, and to the newer and much broader Ka-band, which incorporates photo radar. We also measured the ability of these detectors to elude a radar detector-detector called VG-2, which is used by police in most areas where radar detectors are illegal: Virginia, Washington D.C., and seven provinces of Canada. We also tested the propensity of the detectors to set off other detectors in the vicinity. After all that, and a thorough review of each detector's features and user-friendliness, we declared a winner.

    We were taking a breather when along came a deadly, new law-enforcement weapon, lidar. In the speed-detection game, lidar uses a laser beam instead of microwaves, as radar does, to clock vehicles. Lidar was hailed as a death blow to radar detectors because they are blind to laser beams, and therefore cannot offer warnings.

    It turns out that laser beams are detectable, but in the way that the sound of a guillotine is detectable to the condemned--he hears it at the moment his head is lopped off. Still, the detector industry soon offered lidar detectors. We tested three of them in December 1992 and came away feeling that while they were inexpensive--under $150--they didn't provide much real-world protection because the laser beams fired by police lidar do not desperse and scatter like radar emissions: the "warning" comes only at the moment the officer has fired a beam at your car. Less importantly, these individual units added to the detector clutter on the windshield.

    We did, however, discover that the use of powerful lights can reduce--and sometimes defeat--lidar's effectiveness (C/D, November 1993) and buy time for drivers to slow down after their lidar detectors go off.

    While this was going on, the radar scene heated up. Two years ago, the Federal Communications Commission authorized tripling the breadth of the new Ka-radar band that radar manufacturers could use. Ka-band has been used in this speed-control game since 1989, and it wreaked havoc until the detector industry responded with new "wideband" detectors that could sniff it out. When the FCC expanded the Ka-band, it upped the ante and sent the industry back to the drawing boards. Just recently, a new Ka radar gun, the BEE 36, turned up--and it was no surprise to all us paranoids that it operated in that newly wider band.

    Now the industry has responded with detectors that sweep both this broad Ka-band and the X-and K-bands, and also include a lidar detector. The makers call them integrated superwide-band radar/lidar detectors. At press time, no fewer than five makers offered them: Bel, Cobra, Escort, Uniden, and Valentine (Whistler had not yet begun production of its new 1290 model). Before we look at them, though, let's consider what the detectors are up against.

    Microwave radar has become quite sophisticated since its introduction as an enforcement tool in 1947. Radar's switch in 1965 from the antiquated earth-station S-band to the portable X-band made it realistic for mobile police use. The detector industry popped up soon there-after. These early police radar systems were easily detectable because they were always "on"--that is, they emitted microwaves continually in what's called "steady-state" radar.

    Over the years, the radar-gun makers have pushed the envelope to find new ways to surprise the speeding motorist with radar. Police soon could clock motorists while patrolling or parked, and from the rear of their patrol cars as well as from the front. "Instant-on" radar gave police a huge advantage; the telltale radar system can be "turned off," undetectable until the officer flips a switch to take a reading. Zap, you're dead. Even today, the only chance the detector-equipped motorist has with instant-on radar is that he'll catch a signal from a car in the vicinity that is being clocked.

    Despite all this slick hardware, X-and K-bands are still the ones the motorist is most likely to encounter. The old X-band frequencies run in a narrow range from 10.500 to 10.550 gigahertz (GHz). The FCC also permits burglar-alarm motion sensors and supermarket door openers to operate there; radar detectors often cry wolf as their drivers pass them.

    The K-band has been around since the Seventies, and is a bit wider--from 24.050 to 24.250 GHz. There are perhaps 200,000 radar guns in the hands of police, according to RADAR, a group representing the detector industry, and about 70 percent of those guns operate on the old X-band and 30 percent on K-band. K-band radar is considered to be more accurate than X-Band radar, and is preferred by many police departments. Because the feds allow few devices other than police radar on the K-band, most K-band radar detector warnings are the genuine article.

    When the FCC authorized police use of the Ka-band in 1982 (radar gunmakers did not produce new technology until 1989, when photo radar arrived on the scene), the frequency available for clocking speeds ran from 34.200 to 35.200 GHz. The 1992 expansion stretched the playing field from 33.400 to 36.000 GHz.

    Ka-band radar guns have yet to gain wide acceptance, and to date there are only a few hundred guns out there. The now-notorious photo radar, an unmanned roadside system that photographs license plates as they blow by, was the first new system on the Ka-band. It uses a 34.300 GHz frequency.

    Another new police weapon we examined in our last test was the Stalker, a new player on the Ka-band at 34.700 GHz on your listening dial. Last summer, the most recent newcomer on the Ka-band, the BEE 36 shooter, turned up at 33.800 GHz.

    The expanded Ka-band has presented a particular challenge to the detector industry. First of all, the band is a whopper detectors must scan a band more than ten times the breadth of the X-and K-bands combined. The makers of these detectors must cover the entire breadth of the band because the gunmakers could, at some future date, simply change frequencies.

    Complicating the problem are the X-Band and K-band detectors used by your fellow motorists. Most of these emit microwaves at frequencies that fall into the Ka range at 34.680 GHz, which can set off the newer, superior Ka-band detectors. (It is these Ka-band emissions that alert the VG2 radar detector-detectors.) But if a Ka-band detector is designed to ignore 34.680 GHz readings to avoid falsing from other detectors, it will probably also miss the Stalker, a radar gun cleverly designed to operate at 34.700 GHz (in some versions).

    Lidar presents a different challenge for both the detector manufacturer and the detector-equipped motorist. It uses a laser beam (at a 904-nanometer wavelength) instead of microwaves as the speed-measuring medium. The two lidar guns used by police are the LTI 20-20 and Kustom Signals ProLaser. The beams cast by both these hand-held guns are tightly focused: even at 1000 feet from the source, they are barely six feet wide. Unlike radar, which can't distinguish a target car from others in close proximity, the cop armed with a laser gun can pick out cars in crowded traffic.

    The motorist faces an uphill battle with lidar--particularly the LTI 20-20, which operates more quickly and with greater accuracy than the ProLaser. The problem is not the lidar detector's sensing ability: all of them in our last test reliably detected lidar. It's the laser beam itself. Unlike radar microwaves, which fan out from the gun and reflect off trees, buildings, other cars, and over hills, a laser beam stays on its narrow path, and isn't easily reflected. Which means that if your laser detector goes off (baning a false alarm), you've just been hit by a cop who had your car in his sights. The whole process can take as little as a half-second.

    However, we discovered that these detectors, in rare circumstances, can pick up reflections. We also found, since our last test, that the best of these newer detectors will sound an alarm consistently if the car they are mounted on is directly behind a target car, and both cars are more than 1000 feet or so away from the laser source. More encouraging is the rumor that many cops apparently don't like lidar. Compared to radar, which can be left on to clock cars automatically, lidar is proactive, requiring the officers to park, roll down windows, and zap motorists.

    These new superwide radar and lidar detectors have their work cut out for them. They must monitor three microwave band widths--one of which is vast, another of which is loaded with irrelevant microwave "noise"--and they must do this while maintaining the highest possible sensitivity. They must also optically monitor for laser beams in daylight and darkness, all the while avoiding false alarms from other light sources. They must present these warnings to the driver logically, while remaining user-friendly. Some detector makers even try to design their local oscillators to avoid Ka-band emissions, making them invisible to the VG-2. Finally, this electronic wizardry must be contained in a box about the size a cigarette pack, and must cost no more than a couple of speeding tickets.

    Our tests were conducted at the nearby Chrysler proving grounds. It has roads and terrain very much like the real world, except that there is no radar interference from police or other detectors. The radar sensitivity tests were conducted on a straight road 1.5 miles long, with a number of gradual dips and low hills at one end. Our intention was to send a weak signal to better test the sensitivity of the detectors, so we aimed the guns directly into the first hill, which sent a piddling signal into the distance. We tested in all three formats--X-, K-, and Ka-band--in both steady-state and instant-on modes. Because the Ka-band Stalker gun is in such limited use, we chose instead the increasingly popular BEE 36 unit for Ka testing. We conducted photo-radar sensitivity tests, VG-2 tests, and the detector interference tests on shorter straightaways.

    Lidar sensitivity tests require creativity, and we've changed them since our last test. While all the detectors can detect laser from miles away, variables such as the accuracy of the aim and beam variance make a simple range test unreliable. Instead, we determined how well the detectors could pick up just the softer, outside fringe of a beam. We set up a target platform 2000 feet away. It was placed at one end of a straightaway, with its center five feet above the wound. At the other end, we securely locked an LTI 20/20 onto cinder blocks and aimed it at the dead-center of our platform (see picture). (Picture omitted) Switching on the beam, we then moved the detectors from the outer edge of the beam towards its center until the alarms sounded. This first-of-its-kind test for laser sensitivity worked superbly, and revealed marked differences among the detectors. We also checked the detectors for their field of view, which is how well they could see beams that come in at angles. This ensures that the officer's angle of laser fire (for example, from a median) is taken into consideration. It also maximizes the possibility of finding the rare lidar beam reflecting off other cars.

    We created a 100-point ranking system. Fifty points were assigned to radar sensitivity, since it's still the most widely used. Ten points were assigned to lidar sensitivity (there are about 2500 laser guns at work in the U.S., still a small number). Features and ergonomics were allotted a maximum of 20 points--basic quality, ease of mounting to the windshield or visor, audible and visual alarm discrimination, and filtering-mode usefulness. We also gave 15 points to a selectivity rating; this calculated figure compares the detector's radar and lidar sensitivities to its penchant for false alarms. (It would be easy to build a detector that never falses--and never sniffs out radar, either. Conversely, you wouldn't want a detector that is so sensitive that it falses all the time.)

    Finally, we rated the strength of the detector's audible alarms. Five points were given to the loudest detector alarm (based on the average of all four alarm modes), with the other detectors rated proportionately.

    Remember that our findings apply only to these detector models, and not to a maker's entire product line. Price does not figure into our ratings; given the cost of even one avoidable ticket, we think it's a minor factor. The charts do, however, provide both the list price and the price available from a sampling of discounters. Throw in our test data, and you can decide which one best fits you, particularly if you know what police-enforcement systems are used in your driving area.

    This may appear to be the same detector that won our last detector comparo, but look closely and you'll notice an extra 0.2 inch of housing grafted to the bottom that houses its new lidar function. Even without its lidar score, this detector could have won the test on its radar capabilities alone. Impressive performance on lidar detection merely extended the Valentine's lead.

    Excluding its Ka-band attributes, this detector continues to set standards for radar detection. In all modes--steady-state or instant-on radar, in filtered mode or not--the Valentine could sniff out the widely used X-and K-bands at greater distances than the other detectors. Oddly, the Valentine placed dead last in sniffing out BEE 36 Ka-band, although its warning was still sufficient--from a distance of a third of a mile.

    Valentine's six laser-sensing diodes do a fine job. By a small margin, the Valentine took the lead in laser sensitivity, and was a close second to the Bel in field of view. Unlike the other detectors, it did not false on laser.

    This detector shows thoughtful design. The plug that goes into the lighter fits snugly in any car. The audible warnings are easily distinguishable, including the new laser alarm with its three LED bars and European-type warning siren. Alarm volume, revealed on the front power knob, is easily discernible.

    We've changed our mind since the last test, though, about the Valentine's windshield mount. The suction cups work stubbornly, and the plastic quick-release tab for the cups is easily broken. But we gave extra points for the Valentine's unique ability to tell where the radar is coming from, as well as how many signals it is tracking. It presents this information through a display of arrows (they don't work for lidar) and an LED counter on the detector's face. Casual users might be annoyed by this information, but we find the blinking arrows a boon for recognizing false alarms as well as tricky radar traps.

    The Valentine can false often on its most sensitive mode, but it compensates by offering two filtering modes, called "logic" and "advanced logic," that do a good job of stifling wolf cries. The advanced-logic mode reduces X-Band sensitivity somewhat.

    This detector was the least likely in our tests to set off other detectors. More important, the VG-2 is essentially oblivious to it.

    Excellence doesn't come cheap. The Valentine One with Laser Warning is available only from the factory for a pricey $399. If you have an older Valentine One, don't fret: for between $105 and $200, depending on its age, the company will retrofit it for superwide and lidar capability.

    In what looks like a replay of the last detector test, Bel-Tronics once again takes second place with its flagship model, now called the 645STi. While it still finished a considerable 27-point margin away from the first-place Valentine, its well-rounded abilities in finding radar and laser helped it nail down the second-place spot.

    The Bel bests the bunch at sniffing out the BEE 36, and can almost match the class-leading Cobra in locating photo radar. While its K-band performance was respectable, it consistently was the last to sniff-out X-band, a real problem. This might explain the Bel's respectable showing in the falsing test, which has many stray X-band signals. Still, its selectivity score demonstrated a good compromise of sensitivity versus falsing rejection.

    The Bel's laser function was second only to the Valentine. The 645STi nearly matched the class-winning Valentine for sensitivity, while excelling in field of view.

    This detector suffered in the features and ergonomics column. The 645STi's chirping warnings average only 72 decibels and are much harder to distinguish than those of the other detectors. With the display darkened, it is nearly impossible to distinguish, from all the chirping, just what the threat is. The windshield mount is aggravating--it's bigger than the detector itself and requires a screwdriver to adjust, an annoyance when remounting. These factors are mitigated by the 645STi's warning lights, which clearly display the threats, even at night. The Bel's volume control is easy to set, and is remembered by the detector when it's turned off The VG-2 won't find the 645STi until it is only 15 feet away.

    The Bel lists for $399, but we found it advertised in catalogs for $253. (Bel makes a 645i which retails for $329, but it is not invisible to the VG-2. We can't vouch for Bel's claims that it performs similarly to the 645STi.) If your locality doesn't use X-band radar--and many don't--the 645STi is worth considering.

    The Passport from Escort delivers well-rounded performance for its moderate $229 purchase price.

    The Passport finishes second to leading Valentine in locating X-Band, although the city mode (most filtered) lops in half the X-band range. The Passport is less effective at finding K-band, providing a warning at a third of a mile in every instance. This unit will find BEE 36 Ka reliably, but it stumbles over photo Ka-band, providing, at just 240 feet away, the last warning of all the detectors.

    The Escort was slightly less sensitive at finding lidar than the leading detectors. In the area of lidar, the Passport falsed more than the other detectors. But it scored above par when it came to false radar alarms. This was especially true in the city mode, where the Passport falsed only twice inside our 14-mile test loop (the Uniden, by comparison, falsed 18 times.) Even so, the Escort collected only seven points out of 15 in selectivity, because its overall sensitivity was a significant step below that of the Bel and Valentine.

    The Passport isn't likely to sell in truckstops, nor will it be of much use to Canadian or Virginian readers: the VG-2 can smell this one coming from nearly 700 feet away. But the Passport 4500 is an easy detector to live with. Its windshield mount is effective and easy to adjust, without all the bulk and complexity of the other detectors. The Escort's automute feature and auto-dimming features are also helpful. We have only two complaints with the controls: the on-off thumbwheel located on its side needs numbers to indicate volume level. And the Passport's loudest warnings average only 74 dBA--not loud enough for us. Crank up The Police, and you might miss the real ones out there waiting with eager fingers on laser triggers.

    The Bel and Valentine may do a better job than the Passport at finding radar and laser, but they are also more expensive. The Passport 4500 is available only through the company.

    In what is beginning to look like test results based on price, the Cobra shares a last-place finish with the Uniden, both of which are discounted for $150.

    Interestingly, Cobra got the tough part right--finding radar on the difficult-to-sweep Ka band. In BEE 36 performance, the RDL-512SW placed second behind the class-leading Bel, and the Cobra could find photo radar better than all the other detectors.

    It's the easy stuff, meaning X-and K-band radar, that this detector needs work on. It placed second to last in both X-and K-band sensitivity, and was particularly weak at finding instant-on K-band in city mode. That mode presents a problem for X-band, too. Like the other detectors, the Cobra's city mode keeps a lid on falses by remaining mute until the X-band warning rises above a certain threshold. But it seems to take a very healthy dose of radar to make the Cobra sound a warning, especially in the face of instant-on radar, where an early warning is critical.

    Furthermore, the Cobra seems to be looking for lidar with its eyes half-shut. Straight-ahead sensitivity to the laser beams was less than half that of the other detectors. We had to conduct the moving field-of-view test for the Cobra at a distance of 700 feet from the gun, because at 2000 feet (our normal test distance), the Cobra couldn't detect laser from behind the windshield--even when directly facing it.

    Contrary to Cobra's claims, the RDL-512SW is not particularly stealthy. The VG-2 can find it at 550 feet, well within range of an opposing lane on a freeway. On the upside, the Cobra's simple windshield mount is handy, and its audible warnings are strong and clear. It weighs in at very light 6.1 ounces (the Valentine is almost twice that weight). A standard coiled cord would be helpful.

    This detector will dispatch Ka with the best of them, but its X-and K-band performance is weak, and some might consider its laser performance as nonexistent. Consider its abilities to be commensurate with its price. For a little more money, the Escort delivers much more reliable warnings.

    With a list price of $270, and a street price of $149, Uniden's best laser/radar detector is clearly aimed, like the Cobra, at the budget market. While the Uniden does a good job detecting lidar and some radars, it does an even better job finding false alarms, which is the primary reason for its last-place tie finish.

    When facing the most popular guns--X-and K-band--the Uniden is a mixed bag. Its strong showing on X-band is negated by weak performance on K-band, particularly when facing steady-state radar in the city mode. The Uniden's photo-radar performance was marginal. Interestingly, the Uniden had no problem with the new Ka-band BEE 36, just like the Cobra.

    Uniden has made an admirable effort with its first stab at laser detection. In sensitivity, the LRD 9000W-1 placed second behind the winning Valentine, and the Uniden's field of view remained sufficient while mobile, at 45 degrees. The all-red diode laser warning is particularly effective.

    The Uniden's six-point score out of 15 for selectivity does not fully account for this detector's potential for falsing. Occasionally, the Uniden would go off for no reason with a strident K-or Ka-band warning, as if the driver had happened upon an instant-on trap. A few wolf cries like this would make any driver skeptical of an instant alarm--a potentially hazardous situation. The volume-control dial needs work, too. All of its modulation is contained in a tiny sliver of thumbwheel movement, and there are no numbers on the wheel to indicate sound level. Brush the thumbwheel while putting it on the windshield, and you may have rendered your Uniden mute without knowing it.

    Uniden needs to revise its city filtering mode. On that mode, the Uniden mutes all three radar-band signals until their signal strength is over one LED on the Uniden's four-LED strength meter. K-and Ka-band signals are almost always police radar. We think K-and Ka-band detection should remain on full sensitivity in the city mode, as it does in the other detectors.

    The Uniden's aluminum housing feels solid, and its suction-cup mount, while hard to adjust, otherwise sticks well. We can see why Uniden makes no claims for this detector's level of stealth. It set off every detector we brought near it (including other Unidens), and will snitch to a VG-2 detector-detector from nearly half a mile away.

    For skinflints torn between these last two detectors in the test, try this advice. If you despise false alarms and are willing to sacrifice laser protection, go with the Cobra. If your car is so loud that you can't hear a falsing detector anyway, go with the Uniden. Make sure you're buying the LRD 9000W-1, not the LRD 9000W, which covers only wideband Ka.

• BEL 645STI
  Bel-Tronics, Ltd. 8100 Sagl Pkwy. Covington, Georgia 30209 800-341-1401 USA 800-268-3994 Canada
• COBRA RDL-512SW
  Cobra Electronics Corporation 6500 W. Cortland Street Chicago, Illinois 60635 800-262-7222 312-889-8870
• ESCORT PASSPORT 4500
  Cincinnati Microwave, Inc. 5200 Fields-Ertel Road Cincinnati, Ohio 45249 800-433-3487 USA 800-667-5452 Canada
• UNIDEN LRD 9000W-1
  Uniden America Corporation 4700 Amon Carter Blvd. Fort Worth, Texas 76155 817-858-3300
• VALENTINE ONE WITH LASER WARNING
  Valentine Research 10280 Alliance Road Cincinnati, Ohio 45242 800-331-3030 513-984-8900