To understand a radar detector, it’s essential to understand what radar and radar guns are. Radar is an acronym for radio detection and ranging and, just as the name suggests, is a technology that uses radio waves to “see” an object and determine its distance and velocity. Police radar guns emit different radar bands like X band, K band, or Ka band. (If you want to do a deep-dive, there’s a thriving radar detector enthusiast community on Reddit.)
However, radar detectors are not cheap. Even entry-level models will cost two or three hundred bucks, and top-of-the-line models run closer to $1000 than $500. Before you plunk down your hard-earned cash on a radar detector, here are some things you should know.
Legality
For the most part, radar detectors are legal for use in personal vehicles in most U.S. states—but there are exceptions. Radar detectors are prohibited for use in the Commonwealth of Virginia and the District of Columbia. In Puerto Rico, radar detectors are legal in all passenger vehicles but illegal in commercial vehicles. North of the border, radar detectors are legal in British Columbia, Alberta, and Saskatchewan but illegal in all other provinces. That said, anyone considering using a radar detector should check their local laws, because this article is not legal advice.
Under U.S. federal law, the use of radar or laser speed detectors is illegal nationwide in all commercial vehicles over 10,000 pounds. This includes most 18-wheelers. In commercial vehicles under 10,000 pounds, radar detectors are allowed—except in Illinois, Minnesota, New Jersey, New York, Virginia, and Washington, D.C. Radar detectors are always illegal to use on any United States military base.
California and Minnesota have laws against devices attached to a windshield that obstruct the driver’s view. No matter where you live, we’d advise against attaching any device to your windshield that a motor officer might construe as obstructing your view. It’s a judgment call, but we prefer not to give the cops any reason to judge us or our vehicle.
Quiet vs. Noisy
False alarms are a big issue, so many manufacturers advertise their detectors as “ultra-quiet”—meaning, they filter out false alarms from motion-detecting doors on storefronts and blind-spot monitors from other vehicles. If your radar detector is not quiet, i.e., not good at filtering these out, you’re in for an obnoxious drive that will give your heart a workout.
However, some folks might prefer their radar detector to sniff out and alert every possible radar signal on the road. While providing more noise, they’re theoretically less prone to missing actual police.
Protection
Radar detectors will sometimes miss staked-out cops due to a variety of factors. Lidar is becoming more and more prevalent, and conventional radar detectors can’t pick that up. These devices aren’t ticket-proof—think of them more as a wingman in case you lose track of your speed. Even if they work most of the time, it’s better than not having one at all.
Lidar
Lidar guns (more commonly referred to as laser guns) provide law enforcement with a virtually instant readout of your speed. Lidar is far more difficult to evade than traditional radar because it’s nearly undetectable by radar detectors unless it’s on and already measuring your speed—and by then, it’s probably too late.
Crowdsourced apps such as Waze are actually quite handy at alerting you to a cop using a lidar gun than a windshield- or dash-mounted radar detector. If you really want to beat lidar, look into laser jammers.
Ticket Guarantees
Yes, some radar detector brands, like Escort and Radenso, offer ticket guarantees. Of course, there are a bunch of terms and conditions to comb through, but if you get a ticket while using one of their radar detectors, you might have a chance at getting that money back within a time period. It’s something to keep in mind through your purchase process.
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