Radar detectors are very useful tools to help drivers avoid speeding tickets. To help explain how they work and clear up some of the most common sources of confusion, let’s go over the top 10 most frequently asked questions people have about radar detectors.

Top 10 Questions about Radar Detectors

1) Do radar detectors really work?

Yes. They’re designed to detect a police officer using a radar gun at a distance to clock cars way up ahead of you, before he is clocking your speed. Your objective is to slow down to the speed limit before he can clock you. The more sensitive detector and the more effective it is at filtering out false alerts, the better.

2) I passed a cop but my radar detector didn’t go off. What happened?

Radar detectors are not police car detectors. They’re radar detectors. If a police officer doesn’t have a radar gun in his car or if he has his radar gun turned off, your detector will not alert.

Sometimes they even do this on purpose where they keep their radar guns turned off, waiting for a speeder. Only when they see someone they want to clock do they turn on their radar gun. This is called “Instant on” (I/O) as opposed to “Constant on” (C/O). It’s one reason that you want a sensitive detector. This way you can pick up officers as he’s clocking cars way up ahead of you. Sometimes the only advanced warning you get may be a shot of instant on a mile or two up the road.

(It’s actually very common for your radar detector to not alert when a cop is present. This is one of the most common misunderstandings and it leads many people to think their radar detector is broken, incorrectly programmed, or needs to be returned.)

3) Why is my radar detector alerting even when there’s no cops around?

There are many sources of radar that can trigger your radar detector. Police radar guns are just one of the sources. Some other examples of “false alerts” would include automatic door openers in front of grocery stores and drug stores that use radar to sense when someone is approaching, speed signs on the side of the road, and even newer vehicles that use radar-based blind spot monitoring systems and collision avoidance systems.

Newer and better designed radar detectors offer a variety of different filters to help you filter out many of these sources of false alerts while still alerting you to police radar so that you actually pay attention when it goes alerts. The older and lower end detectors are a lot like the boy who cried wolf.

4) Will a radar detector help against police using laser?

No. Unlike with radar, you won’t get any advanced warning against police using laser guns. If your radar detector does go off when you are targeted (and many times it won’t because the laser beam is so small), your radar detector is little more than a ticket notifier. By the time it goes off, the officer already has your speed.

Against laser you need a laser jammer. Laser is in use all over the country now so a good laser jammer will pair nicely with a radar detector. I recommend the AntiLaser Priority.

5) Will a radar detector always help me avoid speeding tickets?

Definitely not. Countermeasures are designed to help lean the odds in your favor, not make you invincible. Even with the best equipment on the market, you can still get tickets. For example, an officer driving behind you can drive the same speed as you and then look at his speedometer to measure your speed and give you a ticket from that, so you’ll want to stay alert to your surroundings either way. Radar and laser are the two most common ways that police try to catch speeders so those are two of the most useful tools you can have. There are also helpful cell phone apps you can use to add another layer of protection. One app I recommend, Waze, allows you to where other drivers have marked where they’ve recently spotted police. A good countermeasure kit includes a quality radar detector, laser jammer, and waze. It’s all about layers of protection and helping to swing the odds in your favor.

6) Are radar detectors legal?

It depends on where you drive and what you drive. In the U.S., they’re legal everywhere except Virginia and Washington D.C., or on military bases. This applies only to passenger vehicles. They are also illegal all over the country in commercial vehicles over 10,000 lbs and all vehicles over 18,000 lbs. Otherwise yes, radar detectors are legal.

Some radar detectors like the Redline EX, Uniden R3, and Stinger VIP are especially popular in those areas because they are immune from detection by radar detector detectors.

Laser jammers are illegal in the US in 10 states including California, Colorado, Illinois, Minnesota, Oklahoma, South Carolina, Tennessee, Texas, Utah, and Virginia, as well as Washington D.C. The penalty for having jammers is very minor (basically a fix-it ticket) and when jammers are used properly, the officer won’t even realize you have them in the first place.

Radar jammers, however, are highly highly illegal, as in huge financial penalties and prison time so no one bothers to make or sell them here.

7) Where’s the best place to mount my radar detector?

Generally the best spot is up high on your windshield, just to the left of your rearview mirror, hidden behind a tint strip as you can see in the photo above. It’s out of sight of other drivers and thieves, you can free up your cig. lighter and have a cleaner install by hardwiring your detector, and you’ll get maximum radar detection performance mounting it up high. You’ll give up some laser sensitivity since you’re moving your detector farther away from the primary laser targets (headlights, front plate area, and grill), but laser detection doesn’t matter too much so it’s a worthy tradeoff.

The most convenient place to mount is down low on the windshield, but you’re giving up the benefits I just mentioned.

Some people like to hang their radar detector underneath their rearview mirror using a custom mount. I find this location means it gets in the way of my view a bit in smaller cars and the detector is still pretty visible to others outside the car, but it can be a good alternative if you’re finding the suction cups aren’t holding well or you live in an area where mounting things to your windshield is illegal (more than half the states!). The Blendmount is a popular option for people looking to go this route.

8) How do I configure my radar detector?

There’s two things you need to know about. First you need to know how to configure the settings of radar detector you purchased. I have free tutorials available for many different popular radar detectors. Click here to see my radar detector setup tutorials.

Some of the settings you need may vary depend on where you live, where you drive, and what you see around you. Check out this tutorial to learn how to program your detector for your area.

9) What’s the difference between cheap detectors and high end detectors?

While some detectors offer additional bells and whistles like arrows, redlight camera alerts, or bluetooth integration with your phone, if you want to know what the difference is between cheap detectors and high end detectors, ultimately it boils down to two main things: Range and filtering.

Range is one of the most important aspects of a radar detector. It’s what lets you pick up the police using radar guns way up in the distance. The more sensitive your detector, the better your odds at picking up radar in the distance before it’s too late. In the wide open desert you can easily get miles of range. In curvy mountainous terrain with radar absorbing trees you may be lucky to get a few thousand feet. In either situation, picking up radar at a distance can mean the difference between a ticket or not and the higher end detectors generally do a much better job than the lower end detectors, particularly in the tougher scenarios.

The other thing is filtering. There are many sources of false alerts as was mentioned earlier and if the radar detector is constantly bombarding you with false alerts, you’ll learn to ignore it and so you won’t pay attention when the threat is actually real. Higher end radar detectors offer more effective false alert filters to help you minimize the false alerts.

So while any radar detector can go beep when the police are using radar nearby, the higher end detectors can go beep in a way that best helps you avoid speeding tickets.

10) What’s the best radar detector?

Just like with cars, it’s not always which one is best for all people, but which one best suits your preferences and needs. To see my recommendations among the very best detectors and which one would best suit you, check out my radar detector buyer’s guide.