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. Most likely, the police car you passed 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. With the radar off, there was no signal to detect and the detector stayed quiet.
Another possibility is that the officer was using a laser.
Q. Why does my detector go off for no reason sometimes?
A. Very likely it's receiving a radar signal, but not police radar. In town, detectors frequently alert on X or K band in reaction to radar-controlled automatic door openers. On the open road, occasional Ka-band false alarms can be expected, usually caused by radar detectors in passing cars.
K-band false alarms have become a much bigger problem. Many are due to the proliferation of vehicular Blind Spot Monitoring systems. These use K-band radar and share the frequency with police radar. Another culprit is the traffic-flow radar increasingly being installed along highways by transportation departments.
Some radar detectors use GPS and software to reduce false alarms. But Escort maintains a death grip on this patented technology and shares it only with its Beltronics division. Based on our experience, some of its GPS-enabled models are more likeable than others, but all are substantially better at camera detection than the competition. View these models.
Q: Does radar work if the patrol car is moving?
A. Yes and moving radar is far more lethal than stationary radar traps. 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: On the highway, why does my detector give short alerts 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. Hypersensitive radar detectors can spot these from a quarter-mile away. 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: 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: How come my detector doesn't alert to red light cameras?
A. If you're driving with a hypersensitive detector you might already be getting camera warnings without knowing it. Camera radar is K-band, FMCW (modulated) and low-powered, making its feeble microwave beam susceptible to being blocked or deflected, particularly by big trucks. During tests we noted up to a 90 percent drop in detection range when truck traffic was heavy.
Until recent years many domestic red light and speed cameras were triggered by pavement sensors, not radar. With no radar signal present, there was nothing to detect.
Most cameras in Florida and Illinois have been radar-controlled for years; both states require "non-intrusive" camera technology, forcing reliance on radar or laser, particularly the former.
In those states a detector with extra-long K-band range can reliably detect red light cameras. Elsewhere, a GPS-enabled radar detector is the best defense. Some models will warn if the camera monitors speed as well red light violations, and display the the distance as well.
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 for mostly city driving, either would be 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 are willing to chance a minor infraction in exchange for dodging far more expensive speeding tickets.
Risk of exposure is minimized by the best laser jammers as they don't generate a jammer-alert tone in the laser gun.