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Radar Detectors: What They Are And How They Work

There's much to know about radar/laser systems used by police, and detectors capable of recognizing them. We discuss features modern detectors offer - including GPS & Bluetooth.

When you're sitting on the shoulder of a highway with flashing lights behind you and a police officer at your window, there isn't much you can say about the fact that you were driving too fast. There's no doubt that said officer already has your excessive speed documented with a radar or laser gun, or they wouldn’t have bothered to chase you down in the first place. In this article, we'll examine how radar detectors and laser detectors work so that you can make an informed purchase and protect yourself from costly speeding tickets that raise your insurance rates.

Police Car With Emergency Lights On

Radar Detectors:

Windshield Mount Radar Detectors
Shopping for radar detectors can be confusing. We examine how they work to help you make an informed purchase.

Radar detectors are essentially microwave receivers that look for radar beams which spread from their source similar to the way light spreads from a flashlight in a dark field. If you were standing far away from that flashlight, you'd see the light emanating from it with greater ease (and from a greater distance) than the person holding the flashlight would see you. You'd have to be much closer to the source of the light before reflections bouncing off you would become visible to the person holding the flashlight.

Radar Laser Gun In Use
Radar and laser guns don’t work well through tinted glass, which is why officers typically use them outside the vehicle or with the windows down.

In a similar fashion, radar guns used by police transmit microwave pulses, look for the strongest signals reflected back, then compare the frequency of the two to determine speed of an object. Radar can determine the speed of another vehicle even when the police car itself is moving. Detecting the presence of a radar trap early is the most essential part of avoiding a speeding ticket. Radar detectors do this by monitoring a number of radar frequencies police use, then alert you to the signal strength to give you a general idea how far away the radar trap is.

Many detectors feature a voice that speaks out loud and explains why the alert went off. Look for this convenience feature, because not having to take your eyes off the road and squint to read small lettering on the display is a big plus.

Laser Detectors:

Typical Laser Speed Gun In Use
A typical laser speed gun used by police.

Laser detectors (also known as "Lidar" detectors) utilize light pulses instead of microwaves to measure speed. Laser readings are much faster because the speed of light is involved, and they hone in on their target faster because the light beams are a lot narrower and more focused than radar beams. In fact, it takes a laser gun less than half a second to lock on and provide a speed reading compared with 3 seconds for a typical radar gun. Not all police departments use laser guns because they're costly, cannot be used in a moving police cruiser, don't work through glass, and require a fixed mounting base for accurate aiming, since the beam is very narrow.

However, laser guns can be detected and defeated. Light they emit may be a narrow beam coming out of the gun, but that beam will widen fast as it travels. By the time it reaches 1,000 feet away where most vehicles are measured for speed, it's approximately three feet wide. At the outer edge of a laser gun's effective range, the beam will have increased to the width of two highway lanes. Because windshield glass completely blocks the effectiveness of laser detectors, they typically include sensors designed to be mounted on parts of the vehicle exterior such as behind grilles or around license plates.

For the best protection, look for laser detectors with two sensors instead of one. This allows them to monitor 360 degrees around you instead of just catching laser beams coming from straight ahead. Permanently-installed laser detectors often come with "laser shifters" that send out an extremely high intensity burst of light to confuse the laser gun long enough so that a driver can reduce speed.

Escort Passport 9500ci Radar-Laser Detector
The Escort Passport 9500ci Radar-Laser Detector.

One complete detector kit that comes with laser shifting ability is Escort's Passport 9500ci. If you've got a system without a laser shifter, Escort’s Front Laser Shifter Pack provides the components needed to add this protection.

Types Of Radar Used By Law Enforcement

The three main types of radar used in the United States are defined by the frequency of the radar waves they emit, measured in Giga-hertz (GHz). All modern radar detectors can pick up all three types, including X-band radar (10.5 to 10.55 GHz), K-band radar (24.05 to 24.25 GHz), and Ka-band radar (33.4 to 36.0 GHz). Lower-frequency radar can be detected from further away, and requires more time and distance to return an accurate vehicle speed reading. It's important to know the difference between the types of bands below when shopping for a radar detector.

X-band (originated in the early 1950s)

X-Band Radar Detector Type

This is the lowest-frequency radar frequency. It can be detected 2 to 4 miles away, but requires a vehicle to be no more than .5 miles away for speed measurement. Other devices that use X-band signals are microwave security systems for buildings, garage door openers, microwave towers, and other equipment. Radar detectors build in filters to prevent false alarms from those items.

K-band (originated 1978)

K-Band Radar Detector Type

This is a mid-range radar frequency that can be used from a moving police cruiser because it supports a pulsing action. It can be detected from .25 to 2 miles away, and requires a vehicle to be .25 miles or closer for speed measurement. K-band guns can also be kept on standby for quick, "Instant On" activation to measure speed when an oncoming car is less than a quarter of a mile away (as close as 600 feet depending on atmospheric moisture conditions). Instant On radar is challenging if the gun has been aimed directly at your vehicle, because your speed has often been computed by the time your detector picks it up. When aimed at other vehicles ahead of you, you'll have a brief warning period to slow down.

Ka-band (originated in 1987)

Ka-Band Radar Detector Type

Law enforcement agencies in the U.S. experimented with, then abandoned, Ka-band photo radar that captures a vehicle image along with recorded speed data. Today, photo radar guns are mostly used outside the United States.

This is a high-frequency radar which offers the same benefits of K-band radar in a faster-acting formula. When used with instant-on, its speed measurement zone of 120-300 feet away is harder to prepare for. Typically, it can be detected from .25 to .5 miles away under normal use when instant-on is not used.

Law enforcement agencies also experimented with a type of Ka-band radar gun featuring a built-in camera that can automatically clock and photograph the front license plates of hundreds of vehicles in an hour. Known as "Ka-band photo cop", this never really caught on because of the high cost of these radar guns and the legal challenges that resulted because the system mails tickets to vehicle owners automatically.

Ka Super Wide Band

Super Wide band is a newer version of Ka, and radar guns that use it have gotten the nickname "stalker guns" because they can be set to any frequency in the Ka-band (up to 36.0 GHz). As a result, detectors built only for K, X, and Ka photo radar will not pick up these super wide band radar guns. Because this is the most commonly used type of radar by police today, it's important to look for detectors that also offer protection from Ka Super Wide band radar.

Radar And Laser Detectors Lose Significant Effectiveness Behind Certain Types Of Glass

Studies show the effectiveness of radar detectors drops off steeply when they're positioned in front of windshields with heavy tint or embedded metallic film designed to block UV rays. Some specific worst-case scenarios where detection capability is reduced by 95% are General Motors vehicles with PPG or Everclear windshields, Ford vehicles with Instaclear windshields, and some high-end European vehicles that also feature double-paned glass.

Laser detection ability can also be reduced up to 80% by glass thickness as well as by darker tints and metallic film which block more light. Laser detectors lose virtually all of their function behind glass, and typically come with sensors designed for external mounting on the vehicle.

Radar Detector Detectors (RDDs) Used By Police

Escort Redline Radar Detector
The Escort Redline Radar Detector.

Depending on design and construction, most radar detectors leak a small amount of signal that police can detect by using a "Radar Detector Detector" (RDD). In states where radar detectors are illegal, police will use RDDs actively. However, radar detectors are outlawed by use in commercial vehicles in all 50 states, so police often sit at entrances to truck stops all across the country with RDDs turned on hoping to sniff out violators. Because federal law states police officers do not need a search warrant to perform a commercial vehicle inspection, drivers of such vehicles aren't safe anywhere without protection from RDDs. So even if you don't drive a truck or delivery vehicle for your livelihood, you may want to invest in a radar detector with latest in anti-RDD hardware.

Early equipment used by police to sense the presence of radar detectors used VG2 technology. This is a simpler type of technology and most radar detectors available today can sense when VG2 RDDs are being used with plenty of advance notice. Lower-end radar detectors with VG2 sensing ability feature a circuit that shuts off the detector or puts it into a reduced power mode to avoid being detected. More advanced ones will automatically adjust low frequencies to dodge VG2 and continue to operate while remaining invisible.

Spectre is a more advanced RDD technology that keeps being updated, and a form of Spectre is what you're most likely to run into on the road. You'll find detectors such as the Escort 9500ci, Beltronics STiR Plus, Escort Redline, and Beltronics STi Magnum provide the highest level of protection against being noticed by Spectre.

Radar Detectors With GPS

Escort Passport 8500ci Plus Installed Radar Detector With Built-In GPS
Escort Passport 8500ci Plus Installed Radar Detector with built-in GPS.

We offer radar detectors such as the Escort® Passport 8500ci Plus Installed Radar Detector with built-in GPS (global positioning system) capability. This type of radar detector won't give you directions, but it will track your exact location and speed at all times. This allows the detector to warn you accordingly if you're approaching thousands of locations in the U.S. and Canada where red light cameras, speed cameras, and speed traps lurk. Some detectors come preloaded with those locations, but all of them typically offer access to a database that is updated regularly.

You can also program GPS radar detectors with your own additional high-risk areas. Since the radar detector knows your physical location at all times, it's easy to receive reminders when you're nearing an area where speed limits drop excessively, or false alarms from building security systems need to be ignored. Those who own this type of detector swear by them, saying they're very highly effective.

Installed, Non-Portable Detectors

Components Of Fully Eqipped Radar System
Components of a fully-equipped radar system that's permanently installed.

If you travel highways regularly and plan to get the most out of a radar detector, investing in a permanently installed system may pay dividends in the long run. Unlike dash-mounted units which are visible to police, installed systems conceal displays and control switches by mounting them permanently in the vehicle's center console - where they blend in and resemble other OEM equipment. Once installed, you'll have the highest degree of protection against all forms of speed traps, theft, and prying eyes of police officers you pass around town from day to day.

Installed units typically cost more and come with all state-of-the-art technology available such as 360 degrees of laser detection, GPS, laser shifting abilities, and more. Installation will be more complicated, because it means permanently mounting a GPS antenna on the roof, an interface box under the dash, radar sensors behind the front grill, and laser antennas on the front and rear of the vehicle. Installed radar/laser detectors equipped with laser shifters require those to be mounted externally around front and rear license plates as well. In descending price order, Escort's Passport 9500ci, Passport 8500ci, and Whistler's Pro-3600 detectors are just some of the installed kits available.

Whistler Pro 3600 Remote Laser-Radar Detector
Whistler Pro 3600 Remote Laser-Radar Detector.

Bluetooth Linkup

Escort 9500ci Smart Cord
Escort 9500ci Smart Cord.

If you’ve got an Escort 9500ci detector, the 9500ci Smart Cord add-on device creates a linkup between the detector and an iPhone or Android device. This allows you to stream information from databases containing locations of red light cameras, speed cameras, and speed traps.

To help guide you through the selection of radar and laser detectors, we have set up our website to provide you as much information as possible about each product. Be sure to use the menu on the left side of the screen to help specify your choices. Here, you can narrow down your search to features such as display color, operating bands, voice alerts, and price range, to name a few. We also offer complete selections of radar detector power cords, accessories, and windshield mounting suction cups you may need. These extras will help you finish off the installation of your new detector.

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