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. An array of equipment shares K band with police radar. In town, commercial automatic door openers often cause false alarms. On the highway, Blind Spot Monitoring (BSM) radar systems in vehicles are a huge problem. These lane-change warning systems sense nearby vehicles and warn when changing lanes is dangerous.
Other K-band false alarms are caused by traffic-sensing radar (TSR). These monitor traffic flow and volume.
Many newer detectors recognize TSR radar and some GPS-enabled models can lock out door-opener radar. BSM radar is harder to combat since the offending vehicles are in motion. GPS can't be used to counter it, but some detectors use software to deal with the problem.
Q: What's the best radar detector?
A. A GPS-enabled model would probably get the nod. Compared to non-GPS models, most have significantly higher resistance to false alarms. They can also warn of the red light and speed cameras found in 22 states.
The better ones also allow the user to lock out nuisance alerts from radar-controlled door openers. The models ranking highest in a recent test were two Radensos, the Radenso XP ($399), Radenso Pro M ($549).
GPS means the detector knows how fast it's moving, affording additional strategies to reduce false alarms. For example, both Radensos let users set a threshold speed for the onset of audible alerts, up to 55 mph. Radar sensitivity for each band can also be adjusted independently, from 0 to 90 percent. Then they toggle between reduced and maximum sensitivity based on speed.
Q: What's the attraction of a built in detector?
A. Security is one advantage; we've yet to have a remote (built-in) radar detector get stolen. Regardless of 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 downside to remote models is cost. Escort has two, priced at $3000 and $3500. K40 has one that's similarly priced.
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 S4. It's traditionally been the class-leader in performance and features.
Although battery-powered, it can also use a power cord and run on the vehicle's electrical power.
But be prepared for lower performance, especially on the Ka band favored by state highway patrols. Good as it is, the Solo S4 has far less range than a similarly-priced corded model.
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. A short K-band signal could well be from Blind Spot Monitoring radar in a nearby car.
If it's a Ka-band alert, most likely it's 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.
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.
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: there's so much nuisance radar around today that hypersensitivity on K band will make a detector false-alarm incessantly.
Q: What's the best radar detector that will keep me from getting flashed by a red light camera?
A A GPS-enabled model is your best hope. Look for one with high Ka-band sensitivity for long range, along with good filtering to weed out junk radar and keep it quiet. Several of these were compared in a recent test.
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.
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