Radar detectors are pretty simple. They detect when a cop is shooting radar at you, and warn you — often just too late — to slow down. Sometimes you’re lucky enough to catch a cop early, but other times the beeping just lets you know that you’ve helped one of our fine boys in blue meet his monthly quota. But you’re not here wondering what they do, you’re here asking how, a question that’s much more interesting.
Radar detectors contain, within their little plastic bodies, a radio. That radio listens for the frequencies that cops throw out of their radar guns, and alerts you if such a signal is received. Since radar guns are inherently directional — they wouldn’t be of much use if they couldn’t target a specific car — a ping on your radar detector means you, specifically, have been hit by a cop checking your speed. An alert isn’t just a target lock, it’s smoke in the air.
Do they help?
You may have noticed a problem inherent to the design of radar detectors, which is that they can only detect a hit once it’s happened. It’s not really an issue that can be solved, given how radar works. That issue is also compounded by modern police instant-on radar which, as you might guess, can be turned on with a trigger pull. Instant-on means a cop can single you out first, then hit you with radar — even with a detector, you won’t be fast enough to slow down.
Radar detectors listen for cops’ radar guns, and let you know when you’ve been tagged. With the advent of instant-on radar, they’ll often let you know too late to actually help you out. But if you’re lucky, or the cop looking to catch you is lazy, a good radar detector may just save you from a hefty fine or some points on your license.
