If a radar gun is in operation, then will your radar detector surely catch it? And what about false positives and instant-on radar guns? In this article, learn the answers to how accurate radar detectors are and discover features that help you avoid the annoying and irrelevant radar alerts as well as the ones that catch you by surprise.

How Accurate Are Radar Detectors?

Let’s look at radar detectors at multiple angles to answer the question:

• Frequency compatibility

As you may already know, radar guns operate on different bands of radio frequencies. There are the X, K, and Ka bands. Low-frequency and high-powered X-band radar guns are using 8.0 to 12.0 GHz. Higher frequency K-band radar guns, on the other hand, utilize 24.050 to 24.250 GHz. Meanwhile, Ka-band radar guns are operating on a much higher frequency at 26.5 to 40 GHz.

So, how does the bandwidth affect the accuracy of radar detectors? Not much, really, except that your radar detector has to be tuned in to the same frequency or is working on the same plane to detect a radar gun signal within your perimeter.

What matters more than frequency compatibility—that is, a Ka-band radar detector for a Ka-band radar gun, for example—is the device’s ability to operate across bandwidths. Today, it’s not hard to find one that can detect radar guns operating in the X-, K-, and Ka-bands altogether. You can even have a detector that catches all radar signals and laser too.

• Frequency of false positives

Radar technology is not used reserved for radar guns and detectors. It is used in automatic door openers and anti-collision systems in cars, among others. Thus, when you get a beep in your device, it may just be that car beside you or the automatic door of a grocery store you just passed by en route–or radar-gun-trotting police aiming at your car!

So, if you’re talking about accuracy—meaning, knowing exactly that it’s a police radar gun and not any other radar-equipped object—you may have a problem in this area. Usually, radar detectors get false positives from objects emitting signals in the X-band since that’s more popularly used in various technologies.

Because of that, some drivers used to turn off the X-band frequency in their radar detector to avoid the annoying beeping sound of a false alert. However, it could work against them, especially with police departments that capitalize on this tendency.

Thankfully, some radar detector manufacturers have found a workaround for the problem. They have integrated anti-falsing systems that filter out signals from automatic doors, vehicles with anti-collision systems, and the like.

Additionally, there are also updateable databases and GPS lockout systems that work like a built-in Waze app in the device. It allows your radar detector to learn and remember false positives from automatic doors and store information as to where the speed traps are, including speed and red-light cameras.

Anti-falsing systems and GPS lockouts are features that you should be looking at.

• Instant-on or constant-on

Police radar guns operate in two modes. The first one is constant-on, meaning it is continuously transmitting a signal while in operation. This type is pretty easy to detect. An X-band radar gun in this mode, for example, can be detected by your device from up to a four-mile distance, providing you with sufficient warning.

The second mode is instant-on, which allows the police to operate off the radar, so to speak, because a radar detector won’t detect it unless it has been set off. For most targeted vehicles equipped with a radar detector, any response to avoid an overspeeding reading would have proven to be too late by then. This technology grew in popularity in the 1980s.

Before, there’s no way to beat an instant-on radar gun unless you’re not a direct target and your radar detector somehow caught the signal scatter from the targeted vehicle. Today, there are radar detectors that will buy you a small window to respond to instant-on radar guns.

A radar detector with instant-on-ready technology is something that you should consider. Without it, you will be left at the mercy of instant-on radar guns even if your car’s equipped with a radar detector and more so if it doesn’t have an anti-falsing system or GPS lockout as a fallback.

So, if we talk about accuracy in the sense that a radar detector can detect an instant-on or constant-on radar gun, it’s there as long as they’re operating on the same band. But if you mean not taking you by surprise kind of accuracy, it can be different with various radar detectors. And very few are cut out for the job—for instant-on radar gun detection, that is.

• Beam Width

The last aspect that we should inspect is beamwidth. Imagine it as the width of a giant sword. The bigger the width of the sword, the more cars it can hit, including the ones beside it. The smaller the width of the sword, the more precise it is and the less “collateral damage.”

It’s the same with radar guns. In general, the older X-band radar guns are known for having the widest width detection capability among radar guns. Additionally, a laser gun will have a smaller beam width than X-, K-, and Ka-band radar guns. You can say it’s the fencing sword of speed-reading guns.

Thus, an old X-band radar gun with a beamwidth of 65 degrees can read the speed of a car traveling on a lonely highway even without directly pointing it at the vehicle. However, the case can be problematic if the vehicle is driving side-by-side another vehicle or if you add in more cars in the picture.

In any case, your radar detector can catch the radar signal, provided it’s in the same frequency. Whether you’re a direct or indirect target, your radar detector will sense the signal and set off the alarm.

But here, you’ll find a loophole. Should you find yourself getting an overspeeding ticket from a radar gun, and you’re sharing the road with many other cars, it can be argued that the speed of the nearby vehicle was picked up by the wide beam, which is possible, too.

Still, that can be an uphill battle as courts tend to give more weight to the testimony of the police officer. Nevertheless, if we talk about radar detector accuracy in terms of bandwidth, it’s there. Directly or indirectly targeted, a vehicle with a compatible radar detector should catch the signals fired by a radar gun.

Final Thoughts

So, how accurate are radar detectors? We’d say pretty accurate if you’re just looking at it being able to catch radar signals in general. As long as it’s working at the same frequency as the radar gun used in the area, a compatible radar detector should set off an alarm—even if it’s not coming from a police radar gun. And regardless of a radar-equipped vehicle being directly or indirectly targeted, it should catch radar signals nearby.

Still, you’d want a radar detector that will go off only at relevant radar signals or those that are speed-reading related. For this, you’d want to look at special features such as anti-falsing filtering systems, GPS lockouts, and instant-on readiness.