Do radar detectors work?

Indeed they do. Whether yours is powerful or high-tech enough to detect police radar reliably every time is only part of the problem. There’s no nationwide standard for police radar; an officer in rural Nebraska may still use 30-year-old X-band guns (don’t ask us how we know), while urban police will use Ka-band radar or even laser guns. You better hope you don’t come across a Smokey using a laser device. Technically they are lidar guns, providing a virtually instant readout of your speed. Lidar is more difficult to evade than traditional radar. It is undetectable unless it’s on and already measuring your speed, and by then it’s usually too late. Crowd-sourced apps such as Waze are much better at alerting you to a cop using a lidar gun than a windshield- or dash-mounted radar detector.

Conventional radio radar is relatively easy to detect, and a basic radar detector should have no problem picking up these signals. Hopefully, your detector sounds the alarm in time for you to scrub enough speed before the radar gun can accurately measure how fast you were going. More sophisticated modern detectors take a more active role. Not only do they detect police radar and alert you to its presence, but they use an internal transmitter to emit a similar radio signal, mixing it with radio noise to prevent an accurate speed reading on the officer’s radar gun. Additionally, modern radar detectors often include a light-sensitive panel that detects laser beams from lidar guns, and some filter noise from motion detectors at businesses, blind-spot monitors on other vehicles, and even other radar detectors. More on that below.

It’s important to note that no radar detector is 100 percent effective; there’s no guarantee that even with a radar detector on your dash, you won’t get a speeding ticket. Radar technology is constantly improving and being upgraded—and so are radar detectors. Think of your cellphone from just a few years ago versus the smartphone in your pocket today; much like your old phone, your old radar detector may already be obsolete. Consider upgrading to one of the newer models spotlighted above.

Are radar detectors worth it?

Well, that’s subjective. Radar detectors can cost anywhere from a couple hundred bucks to $700 or more, so it’s no small investment. A lot of drivers swear by them, insisting their radar detector has paid for itself many times over. Others say they’re a waste of money and that fastidious scanning of traffic for brake lights and a roof-mounted gumball is better practice.

We’re not here to tell anyone how they ought to drive, but if you drive fast, speeding tickets are a very real risk. If you tend to speed regularly or just have bad luck with speeding tickets, a radar detector could be a solid investment.

Things that set off radar detectors

In addition to how they work and the type of signals they detect, a major difference between older radar detectors and newer, higher-end devices is the number of false alerts given. False alerts can be caused by anything that, like police radar, uses X-, K-, or Ka-band frequencies. This includes traffic monitors and roadside electronic warning signs to emergency vehicles. Modern radar detectors use advanced processing to filter out false signals.

The advanced safety systems so common in many modern cars are among the biggest sources of false alerts these days. These include things like adaptive cruise control, lane-departure warnings, and blind-spot-monitoring systems. Such systems typically use K-band radio frequencies to determine how far away an object is from a vehicle, so just being near another car could set off your radar detector.

Automatic door openers are another source of false alarms—not just garage-door openers but also the auto door openers used by retail storefronts. If you’re using an aged radar detector, simply driving past your neighborhood grocery store could set the thing off. If you’re getting more false alerts than ever, that’s a sign your radar detector may have outlived its usefulness. Consider upgrading to one of the devices above.

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