Q: How come my detector doesn't go off sometimes when I drive right past a cop car?
A. Radar detectors detect radar, not police vehicles. There's a good chance the police car wasn't radar-equipped (90 percent carry no radar).
Or if it was, most officers shut off the radar while they're out of the car on a traffic stop or when using it in instant-on mode. With the radar off there was no signal to detect and your detector stayed quiet.
Q: How come I get so many false alarms on K band?
A. Extended alerts often are due to a Blind Spot Monitoring (lane-change warning) system in other vehicles. Most use radar to sense nearby vehicles and show a warning light in the outside mirror when changing lanes is dangerous.
In town, radar-controlled automatic door openers often are the source. On multi-lane highways—I-70, E-470, I-25, I-225 and others in Colorado, for instance—they're due to traffic-flow radar installed by the state transportation department.
All of these share K band with police radar. One company's detectors use special software and GPS to reduce false alarms. But it controls this patented technology and while competitors might claim GPS capability, their products lack most of the technology's most valuable features.
Q: What's the best radar detector?
A. The answer depends on your expectations and how it will be used. For a daily commute that doesn't involve much highway driving, one of the GPS-enabled Escorts—Max 360, iX—would get the nod. After repeatedly passing a nuisance signal like an automatic door opener, they lock it out automatically. They can also warn of red light and speed cameras.
Two remote (built-in) models with the same capabilities and higher performance are the Escort Passport 9500ci and 8500ci Plus.
For highway driving where long range and fast response are higher priorities, we'd prefer the Escort RedlineXR.
Q: What's the advantage of a built in detector?
A. Security is one advantage; we've yet to have a remote (built-in) radar detector get stolen. That's something we can't say about the $29 junk detector we once left—on the floor—of a beater Honda parked, locked, in Boston's Back Bay for a few hours. Regardless of the value, if it's visible eventually some twit will smash the glass and steal it.
Another advantage is discretion. Detectors are legal in 49 states, but some cops disapprove. Get stopped by an officer like this and expect to be cited.
The best remote we've tested is the Escort Passport 9500ci. Aside from exceptional range, it has high resistance to false alarms and comes with effective laser jammers. Learn more.
Q: Does radar work if the patrol car is moving?
A. Yes and radar on the move is far more lethal than stationary radar. Most of these radars have an antenna in front, another in back, giving them front-rear coverage.
They can also track same-direction vehicles in front of or behind the rolling cruiser. Many also can target the fastest car in a pack, making it hard to hide behind slower vehicles.
Q: I've read that putting the detector up high on the windshield gives it better range. Is this true?
A. That would seem logical, but in 30 years of testing detectors we've never seen range improve by altering mounting height by a few feet.
An extra 50-plus feet might make a difference on rare occasions, but a radar detector is more affected by orientation than height. Keeping it level and pointed down the centerline of the vehicle will maximize range.
Q: I want a detector that runs on batteries so I won't have to deal with a power cord. How do they stack up against the rest?
A. There's only one cordless, the Escort Solo S3. Or you might find one of the discontinued PNI Silver Bullet or Whistler DE1788 models. The last two are very short-range, perhaps okay for low-risk drivers who never stray more than a few MPH over the limit.
But be prepared for significantly lower performance, especially on the Ka band favored by state highway patrols. Even the Solo S3 has barely one-third the range than an Escort corded model like the Escort iX.
Q: Driving in California, I've never seen anything other than Ka band be a real alert. Am I safe turning off X and K bands unless/until I leave the state?
A. Shutting off X band west of the Mississippi is fine, but doing the same on K band isn't risk-free. Although the California Highway Patrol uses Ka band exclusively, several thousand K-band radar units remain in service nationwide, some of them on the West Coast.
But if you're being pestered by K-band false alarms, in your area the risk is low enough to make the move worthwhile.
Q: On the highway, why does my detector alert sometimes when I don't see a cop car?
A. If it's an X- or K-band alert it may be an automatic door opener. A sensitive radar detector can spot these from a quarter-mile away or more. Occasionally a weak K- or Ka-band signal might be from a radar detector in a passing car.
Another possibility is instant-on radar working traffic up ahead. With the radar on hold, the officer triggers it at close range and gets a speed almost instantly.
The windshield-mount model best able to protect against instant-on radar is the Escort RedlineXR. In tests it alerted to this type of radar from several miles away. This was two to three times the range of competing models.
Q: How come my detector doesn't alert to red light cameras?
A. If you're driving with a high-performance detector you might already be getting camera warnings without knowing it.
Until recent years most red light and speed cameras were triggered by pavement sensors. With no radar present, there was nothing to detect.
A GPS-enabled radar detector was the best defense against this type of camera.
The trend now is radar-control, much cheaper to install and maintain. Radar makes the cameras detectable and a few high-performance detectors with exceptional K-band sensitivity can spot them.
That's the good news. The bad news: the only models worth having are all expensive.
Q: What's the best radar detector that will keep me from getting flashed by a red light camera?
In a recent test, the three models best at detecting radar-triggered red light cameras were the Escort RedlineXR, Escort Passport 9500ci and Escort Passport 8500ci Plus. (The latter two are installed models that have GPS.)
Two GPS-enabled windshield-mount models that also performed well: Escort Max 360 and the Escort iX. Neither approached the RedlineXR in range but if you're doing mostly city driving, their greater resistance to false alarms would make either a better camera-fighter.
Q: Sometimes I drive by a cop aiming his radar gun at me and my detector doesn't go off. How come?
A. If he was peering through an aiming reticle it was a laser, not radar. The pinpoint beam is nearly impossible to detect and allows one car inside a pack to be clocked. The only defense is a laser jammer.
Jammers are illegal in 14 states, but many drivers are willing to chance a minor infraction in exchange for dodging a far more expensive speeding ticket.
Risk of exposure is minimized by the best laser jammers as they don't generate a jammer-alert tone to tip off the officer.
Q: Do Rocky Mountain Radar detector/scramblers really work?
A. We've yet to test one that jams anything. Not that you'd want to use a radar jammer, given that it's a federal felony even to possess one.
We broke the story about Rocky Mountain Radar in 1993 [The Little Jammer That Couldn't, Automobile Magazine] and have tested many of its wares in the years since. Aside from being marginal at detecting radar, none exhibited any jamming effect on radar or lasers. Learn more
Laser jammers are legal in 26 states and increasingly popular. Two or more jammers are mounted in the grille area to protect the headlights—and front plate if so equipped—an officer's favorite aimpoint.
Aside from being way too big to fit inside a windshield-mounted radar detector, it's the headlights and vehicle center mass that need protecting, not the windshield.