Ever Wonder Why Your Radar Detector Didn't Go Off?

Ever Wonder Why Your Radar Detector Didn't Go Off?

January 25, 2019

When you purchase a radar detector, it makes sense that you would expect it to go off when you drive by a police officer! After all, that’s why you bought it – to be warned of a speed trap ahead.

But sometimes, you might drive by a speed trap and your detector won’t alert. Even more concerning, you may be used to those pesky speed monitoring signs setting off your old radar detector on K band. If your new Radenso detector isn’t going off in these situations, it is only normal for you to be concerned. But don’t worry – this is perfectly normal, and your detector is probably working just fine!

Since this topic is one that we get asked about often, we have broken down the three most common scenarios where a properly working radar detector may not go off when you expect it to.

Why your radar detector didn't alert you

1. The police officer isn’t actively running radar

One thing to realize about police officers is that they are humans just like us! Granted, they are trying to give us tickets, but just like you and me they are not always working 100% of the time. Sometimes while sitting in their car at a speed trap they are talking on the phone, doing paperwork, or perhaps even slacking off and watching a TV show on their laptop.

Since radar detectors have the option to be activated when a trigger is pulled (and not always be constantly on), what this means is that when the trigger is not being pulled, the radar gun is not emitting any radar waves (the police offer can’t see your speed). And since radar detectors detect radar waves and not merely the presence of the police, it won’t alert! In other words, if the police officer is not actively participating in speed enforcement, there is no threat to the driver and the radar detector won’t alert even though it is functioning properly.

Radar gun trigger

2. Radar speed signs don’t alert due to advancement of detection technology

This one is actually really nice! You probably are familiar with those speed signs that are mounted on the side of the road and flash your speed when you drive by. Older radar detectors that do not have very advanced false-alert filtering capabilities commonly alert to these speed signs, usually on K band.

Since these speed signs are used simply for deterrence, not for ticket issuance, technically they are false alerts that annoy drivers. Some Radenso radar detectors are advanced enough that they can recognize the difference between radar signals emitted by these signs and those that are emitted by real police guns. For example, some speed signs use something called modulated radar that looks very different from continuous wave radar that police use. Other times, the speed signs might use continuous wave radar that is at a different frequency (due to either design or frequency drift from poor maintenance) than real police radar. Since the detector knows these are not a threat, it will not alert and you can enjoy your drive with silence.

3. Laser (LIDAR) is being used instead of radar

Radar is just one type of speed enforcement tool that police officers use. Laser, or LIDAR, is a type of speed measurement that focuses on one particular car instead of a wide swath of the road. Since it operates based on a narrow laser beam (you can think of it kind of like a laser pointer), police officers have the ability to target a specific point on your car such as a license plate or headlight.

Laser (LIDAR) gun being used

While sometimes radar detectors (which often have laser sensors built in as well) can pick up a LIDAR beam that is aimed at the car, it is also normal for the sensor to miss the laser shot completely since the beam is too small. And of course, since laser is being used and not radar, the detector will never alert “Radar” as a result of a laser shot.

To get true protection from laser, we do not recommend relying on a radar detector from any brand including ours. Instead, consider a laser jammer for complete protection.

In conclusion, there are several reasons your radar detector may not alert when you expect it to. While it is normal to be surprised by the level of advanced false alert filtering in high quality, modern radar detectors, your worries will go away the first time you detect a police officer from several miles away and score a nice save!


Questions and Suggestions

Have a question about this article or a suggestion for a new one? We would love to hear from you.