You never know when you’re about to get a speeding ticket. Maybe you’re blazing down the highway at 90 miles per hour, but maybe not. Maybe you’re just a couple miles per hour over the speed limit. And then you hear the wail of the police siren and there are those dreaded flashing blue and red lights.
Do you ever wonder why people who whoosh by you on the road often seem to get away with it? Some guy you saw going 20 miles per hour over the limit is fine, but you get pulled over for next to nothing. It could be that the other guy has a radar detector which helps him to avoid speed traps. Imagine if you had one. You could save hundreds of dollars on tickets and insurance premiums.
If you are thinking of buying a radar detector, but are not sure what you need, check out features and prices for top-selling models in our comparison chart.
- 1 What is a Radar Detector?
- 2 How Does a Radar Detector Work?
- 3 How Do Radar and Laser Guns Work?
- 4 Radar Guns
- 5 Laser Guns
- 6 Types of Radar Bands
- 7 Factors Affecting Range
- 8 Laws Pertaining to Radar Detectors
- 9 Questions to Ask When Shopping for a Radar Detector
- 10 Features and Add-Ons to Look For When Shopping for a Radar Detector
- 11 Escort Passport 9500IX: Automatically Filters Out False Alarms
- 12 Cobra ESD7570: the Most Popular Radar/Laser Detector Online
- 13 Whistler CR90: Speed Camera Info Plus Radar and Laser Detection
Still not sure what to look for in a radar detector? Read on to learn everything you need to know.
What is a Radar Detector?
A radar detector is a device which you mount on your dashboard, clip to your visor, or suction to your windshield. The detector picks up the signals which are transmitted by traffic radar systems used by cops. If such a signal is detected, the device alerts you that a cop is nearby. It may do this by beeping, flashing colored lights, or both.
How Does a Radar Detector Work?
To understand how radar detectors work, it helps to understand how police detect speeding vehicles.
Cops shoot a beam across the road section that they are monitoring. The beams which they use are nothing more than police broadcasts on the X, K or super wide Ka bands, similar to the radio bands which you find on AM or FM radio, only with different shapes and frequencies.
If a vehicle (or any other moving object) should happen to pass into a beam, the beam returns to the source gun with a new frequency. The radar gun then reads the frequency difference and calculates the speed of the vehicle.
All the radar detector does is listen for broadcasts on the X, K or super wide Ka bands. Any of these broadcasts could be police radar signals. Detailed information about the broadcasts is not available, but you can see which band the broadcast is on and what the strength of the signal is along with its approximate distance. Usually you have enough time to slow down before you are caught.
How Do Radar and Laser Guns Work?
If you are still having a hard time picturing how radar guns and detectors work, here is another way to look at it.
A radar device transmits a radio wave. This wave moves at the speed of light. When it hits an object, it bounces back to the radar gun. If the object is standing still, all the radar gun has to do is look at how long it took for the signal to return to calculate its distance (kind of like sonar).
This is a slightly different process when an object is in motion, like a vehicle. If the vehicle is approaching the radar device, the returning signal is crossing a reduced distance. This results in an increase in the frequency of the radio wave. The radar gun looks at the change in that frequency to figure out the speed.
There are a number of different configurations and modes for radar guns. These are the most common ones you may encounter:
This type of radar gun transmits a burst of pulse radar every 67 milliseconds or so.
Quick Trigger (QT)
This is actually a technique for operating a radar gun rather than a specific type of gun. The officer triggers the radar quickly on and off to attempt to check vehicle speeds without signaling radar detectors. It works like Pop, except it is under manual control.
Instant On (I/O)
This is where an officer waits as long as possible and then turns on the radar at the last second without warning.
Constant On (C/O)
This is where a radar gun is simply left on and transmitting constantly.
Sometimes law enforcement officers use laser guns instead of radar guns. These devices transmit a series of light pulses, and the difference in time between the pulses and their reflections allows the device to calculate speed.
Laser guns have a narrow beam which makes it easier to pinpoint just one vehicle. It takes less than half a second to capture a reading, whereas radar guns can take several seconds. The downside for the officer is that the beam needs to be aimed precisely, whereas with radar a broader sweep can be taken.
Types of Radar Bands
This band has been used by police since the 1950s. At 10.5 – 10.55 GHz, it has a high power output and a low frequency, so it is easier to detect than other radar bands. You may be able to detect it as far as 2-4 miles away.
This is the radar band which is used most frequently at 24.05 – 24.25 GHz. You can detect a K-band using a radar detector anywhere from ¼ of a mile to 2 miles away, depending on the shape of the terrain.
Ka-and, Ka Wide-Band and Ka Super Wide-Band are all incorporated into Ka-Band. Originally working over a narrower band, over time, Ka-Band was expanded to use a range of 34.2 to 35.2 GHz.
This band is rarely used in America, and is more common in Europe. It tends to be used for satellite and aerospace communications. In recent years, US cops have begun using it to detect speeders at 13.45 GHz.
Factors Affecting Range
If you have a windshield embedded with metallic film or a tint film, that is going to reduce the range of your radar detector quite a bit (as much as 95%). These types of films are most common in GM, Ford and Everclear windshields.
Any type of glass actually stands in the way of radar detection, but the darker your windshield tint, the more your range is going to suffer.
Laws Pertaining to Radar Detectors
Just how legal are radar detectors? You have probably heard before from some people that they are totally illegal, while others tell you they are not a problem.
The reason you may have heard seemingly contradicting information has to do with the fact that different regions have very different regulations surrounding the use of radar detectors.
Radar detectors are completely banned in:
- Washington D.C.
- Most of Canada
- All U.S. military bases
If you are caught using a radar detector in one of these jurisdictions, you will be hit with a substantial fine and your detector will almost certainly be confiscated as well.
In the following states, radar detectors are illegal in commercial vehicles only:
- New York (over 18,000 pounds)
Outside of the jurisdictions in the two preceding lists, you should be able to legally have a radar detector in your automobile. Make sure however that you look up the state and local laws where you will be driving. Never make any assumptions; laws can change over time.
Questions to Ask When Shopping for a Radar Detector
What type of detector do you need?
Think how you plan to mount your radar detector. You will get the top range from a corded detector suctioned to your windshield. If you want a permanent installation, a remote-mount detector is what you are searching for. If however you will be moving the detector back and forth between a couple of vehicles on a regular basis, you will find a cordless detector most convenient.
Do you need GPS?
If you live in an area where speed traps are regularly set up in certain locations, or where there is an abrupt drop in speed limit along the highway (like a small town in the middle of nowhere), a radar detector with a GPS can be programmed to remember these spots and provide you with a warning when you draw near them. That way you will slow down before you get caught in the speed trap.
Should you buy a radar or laser detector?
You may encounter a cop using either a radar or laser gun while you are driving, so the best option is always a radar detector with laser detection. Thankfully this feature is included on all new radar detectors. The only time it would make sense to go without it is if you are buying an old radar detector to save money. Otherwise, a new radar detector which includes laser detection is best.
Features and Add-Ons to Look For When Shopping for a Radar Detector
When you are driving in the city, you will be surrounded by devices which give off false alerts on the same bands (microwaves, garage door openers, etc.). Obviously if you get too many false alerts, you will no longer be receiving actionable information.
For this reason, a quality radar detector will offer you City and Highway modes. When you are driving in the city, you can select City Mode, which will reduce the radar detector’s range and sensitivity. This will reduce the number of false alerts you get. You can then switch back to Highway mode when you are out of town.
Some radar detectors even have a feature to automatically detect your location and switch between modes. This saves you from having to do it manually.
If you can, try and shop for a device which includes 360-degree laser detection, rather than just one laser sensor. A single sensor can only look for beams in front of you, but cannot detect beams to the side of you or behind you. A 360-degree detector can alert you to pulses on every side of your vehicle.
The drawback is cost; these models are more expensive, so you will need to weigh your priorities.
This is an important feature for driving safety. If you have a device with voice alerts, there will be audible alerts to tell you if radar pulses have been detected nearby. If you do not have voice alerts, you have to check the display for visual information—and since you never know when to check, you have to do it frequently, taking your eyes off the road. Voice Alerts provide you with ease-of-use, safety and peace of mind.
Technically, nothing can protect you from “Instant-On” radar if it was aimed directly at your vehicle. You receive an alert of course, but by that time, the cop already has measured your speed and is coming after you.
So what does “Instant-On” Protection do? If the car in front of you is targeted by Instant-On radar, Instant-On Protection lets you know. This only works on a radar detector which has high sensitivity to the K-Band. You can then slow down in time (hopefully) to avoid being caught yourself. This is a great feature if you can afford it.
VG-2 and Spectre Protection
One of the hazards of using radar detectors is that cops are starting to be able to spot radar detector usage with the aid of devices called radar detector detectors (RDD). The most advanced form of RDD technology, known as “Spectre,” is quite difficult to counteract. Look for a radar detector which provides you with some level of protection.
There are two main types of protection:
Stealth: A device equipped with stealth protection will give you a warning and then automatically shut itself off if it detects RDD.
Invisible: This type of protection is even stronger. An “Invisible” detector in theory can operate without being detected by RDD at all. So this type of device will remain on even if Spectre is in use.
RDD protection can also affect cost, but it can be a very valuable feature.
Radar with GPS
We have touched briefly on this point, but it is worth going into a little more depth to discuss GPS as a radar detector feature.
You may already be familiar with GPS if you use it on your smartphone. GPS stands for “global positioning system.” It uses a network of satellites to identify your exact location. This helps you to navigate in your car or on foot. GPS is accurate to within just a few feet.
GPS also can measure the speed at which you are moving. You can see how that information would help a radar detector to provide you with more useful information in a timely fashion.
This actually comes back to the discussion on City vs. Highway Modes. Remember how we mentioned that some devices can switch back and forth between the two modes automatically? The way this works is by checking your vehicle’s speed using GPS.
You will also recall that GPS can be used to store speed trap information. It can also be used to inform you when you are traveling over the speed limit. A device which is not equipped with GPS has no way to know if you are actually over the speed limit, because it does not know where you are.
So you can stay a lot safer with a GPS-equipped radar detector. This feature is well worth the extra cost.
Radar detectors which feature smartphone compatibility can be connected with your mobile device. You can download an app for your iOS or Android operating system, expanding the capabilities of your detector.
How does it work? Well, let’s say that you have discovered a speed trap in a surprising location. You can send out a notification through your smartphone app to alert other drivers that there is an enforcement area nearby. The app can also alert you to information other app users have provided. So this gives you access to an even wider network of information.
Another thing that you can do with mobile compatibility is set up an app to report the alerts from your radar detector. This allows you to get away from a large display or a noisy device and go with a model which has a lower profile.
Display and Design
A quality display is important in a radar detector. Remember, when you are driving at night, you are going to have to be able to read the display in the dark. Sometimes visibility during the daytime can also be adversely affected by glare. So look for a unit which includes an ultra-bright LED display which is easy to read in a range of conditions.
Warranty, Support, and Manual
Make sure that your radar detector is backed by at least a year warranty. Check out customer reviews to make sure that buyers who had to fall back on the warranty had a great experience with customer service.
While you are at it, also see if buyers had anything to say about the manual which comes with the product. Clear instructions are important, especially if this is your first radar detector. It is common for new users to struggle with onboarding.
Now you know all about radar detectors: how they work, their legality in different states, and the important features to shop for. Ready to buy your own? Scroll back up to our comparison chart to check out features and prices for top models!
Escort Passport 9500IX: Automatically Filters Out False Alarms
The Escort Passport 9500IX is one of the only radar/laser detectors that’s equipped with artificial intelligence. The first time you use the Escort Passport 9500IX, you’ll get lots of false alarms. But over time, this detector’s algorithm will learn how to identify real threats and filter out safe frequencies.
- Get less false alarms. The “auto learn” feature filters a signal if you disregard it 3 times.
- More time to react. The Escort Passport 9500IX’s sensors are super sensitive and give you an ample amount of time to adjust your speed when you need to slow down.
- Downloads traffic camera locations. Pinpoints exactly where you need to slow down.
- Displays signal strength. If you get targeted, you’ll know.
- Provides frequency info. Become familiar with the technology your local police department is using.
- Detects lasers, too. Helps you avoid getting zapped.
- Comes with mounting equipment. The suction cup mount allows you to attach the Escort Passport 9500IX to your windshield.
The Escort Passport 9500IX software doesn’t work with MacOS. Also, you have to pay for a subscription if you want to download updates.
Cobra ESD7570: the Most Popular Radar/Laser Detector Online
Whatever type of traffic monitoring tool police officers in your area are using, the Cobra ESD7570 has got you covered. It doesn’t help you identify traffic cameras, but if you want to go fast on the open road this is the best radar detector to have. It can even identify whether or not a so-called “detector-detector” is being pointed your way.
- Amazon best seller. Even though this detector isn’t fancy, it is very reasonably priced and popular online.
- Guards against detector-detectors. One unique thing about the Cobra ESD7570 is that it can identify VG2 and Spectre I/IV+ Radar “detector-detectors.”
- Bare bones. Has all the features you need to avoid a ticket.
- Adjustable volume. Change the volume if it’s too loud or too soft.
- Precise. The displays helps you figure out if a reading is a “K” band grocery store radar or a real “KA” law enforcement frequency.
- Detects all North American radar/laser guns. This detector identifies every traffic gun under the sun.
- Safety alert warnings. If there’s construction or accident slowdowns ahead, this detector will let you know.
The Cobra ESD7570 can’t warn you about traffic cameras because it has no GPS map capability.
Whistler CR90: Speed Camera Info Plus Radar and Laser Detection
This full-featured detector has a wide range of abilities. The Whistler CR90’s robotic voice provides more detailed information than most other detectors. It guards against both laser beams and radar frequencies, plus it also checks its GPS database for traffic cameras as you drive. You can even connect the Whistler CR90 to your car stereo via its line out jack.
- Verbal voice alerts. A natural sounding computer voice tells you what’s going on as you drive.
- Specific information. The Whistler CR90 tells you detailed information about different radar and laser signals it detects.
- Overspeed warning. Setup custom speed limits that’ll warn you if you lose track of how fast you’re going.
- Laser and radar detection. Notifies you about both types of speed detectors.
- Guards against traffic cameras. The computer scans its GPS database for known speed camera positions as you drive.
- Plugs into your stereo. Connect via the line out jack.
- 360 degree monitoring. Picks up all incoming frequencies, no matter what the angle is.
The Whistler CR90 is one of the best all-around detectors out there, but it’s also significantly more expensive than most other gadgets of its kind.