Radar Detector Guide

It is a rare man or woman who hasn't received at least one speeding ticket in their illustrious driving careers; I know in my undisciplined youth I collected my share. Then I got wise and bought a RADAR (Radio Detection And Ranging) detector.

From humble (and simple) beginnings the radar detector has grown up and is now standard issue with every SUV, sports coupe, sports sedan, and pick-up truck on the American highway; sorry family sedans need not apply.

But like everything else electronic there are a myriad of radar detectors from which to choose. Naturally, the price-points can range from one extreme to the next. Which radar detector is right for you? Only you can answer that question, but we can help you make a more informed buying decision.


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Radar Detectors - How to Find the Best Radar Detector

Radar Detector Guide
AUG
3
2009
TheBard
Aurora, IL

THE SCIENCE OF DOPPLAR RADAR WAVES

One of the technologies law enforcement agencies utilize to enforce the nation's automobile speed limits is the aforementioned Doppler radar. Doppler radar uses a concentrated radio frequency beam to measure the speed of a moving vehicle. Doppler radar beams are emitted from small devices called radar guns, which can be handheld or mounted.

Radio waves, like sound waves, have a certain frequency; a frequency is the number of cycles per unit of time, usually measured in seconds, microseconds, or milliseconds. when the car is in motion, each part of the radio signal is reflected at a different point in space, which changes the wave pattern - creating a Doppler shift.

A Doppler radar gun can calculate how quickly a car is moving towards, or away from it based on how much the frequency shifts. If the radar gun is mounted inside a moving police car, its own movement is automatically factored into the equation. For example, if the police car is going 60 miles per hour and the gun detects that the target is moving away at 10 miles per hour, the target must be driving at 70 miles per hour.

Doppler radars transmit in three principle Super High Frequency (SHF) electromagnetic spectrum bands: X-band (7 to 12.5GHz), K-band (18 and 27GHz), Ka-band (18 to 40GHz), Ku-band (12 to 18GHz).

SO WHAT IS A RADAR DETECTOR?

Radar detectors are designed to intercept Doppler radar signals in some or all of the above mentioned frequency bands giving an audible and visual alarm to the driver. Radar detectors are passive electronic devices and use a superheterodyne receiver (a receiver designed to detect radio waves in the SHF range) to detect radio waves and can only intercept Doppler radar.

A basic (inexpensive) radar detector can only detect radio signals from one direction - front - and are passive. So if the police officer drives up behind you, chances are your detector will not alarm until it's too late. Standard radar guns have a cone, or dish-shaped antenna that concentrates the radar beam, but the electromagnetic wave quickly disperses over a wide area. This means that a radar detector will pick up the radio signal well before the radar gun recognizes the car, if of course you are moving towards the beam.

More modern, sophisticated radar detectors actually take an active role in helping you slip out of a ticket. In addition to the superheterodyne receiver, these devices also have their own radio transmitter, which emits a jamming signal. A jammer works by replicating the original signal from the police radar gun, and mixing it with additional radio noise confusing the radar receiver, making an accurate speed reading difficult to obtain. But be mindful that radar jammers are illegal in most states!

One of the negatives of radar detectors is the propensity of the devices to give false alarms that can occur due to the large number of other devices, such as automatic door openers, and microwave towers, that operate in the same part of the electromagnetic frequency spectrum as radar guns.

Even a top-of-the-line radar detector with jamming system is not 100% effective. Also, law enforcement agencies periodically introduce new speed-monitoring technology, so the state-of-the-art detector you bought yesterday might suddenly become outdated tomorrow unless the detector manufacturer offers periodic firmware upgrades. Popular radar detector brands include Beltronics, Valentine, Cobra, Escort, and Whistler.

HOW TO CHOOSE A RADAR DETECTOR

Radar detectors come in all shapes, sizes and price-points; the one you choose depends on the feature-set you want and how much you are willing to shell out.

Note-worthy radar detector features include:

  • Frequency Spread - Even lower end radar detectors usually cover the full frequency spectrum of U.S. radar and base frequency of LIDAR guns; i.e. Doppler: X-band, K-band, and Ka-band, as well as the most popular Laser band, 33MHz. Units like the Escort can also detect radar guns in the (European) Ku band, while the Cobra also can detect VG-2, a technology police agencies are increasing using to detect radar detectors! Still others like the Whistler offer 360 degree laser coverage as well as well as a wider range of laser frequencies.
  • Displays - How the radar detector displays the information detected is just as important as the fact that it detected the frequency in the first place. Almost all of the radar detector displays use long-lasting LED readouts. Some units like the Whistler can display text in seven selectable colors including red, purple, light, medium, and dark blue, as well as light and dark green. These colors can in turn be programmed for each type of frequency detected. A more common display can be found on the Beltronics, in which the band and signal strength of frequency detected is displayed in red LED. Another type of display like that found on a Whistler uses large color-coded letters to notify you when an emission in a given frequency has been detected.
  • What else to consider when buying a radar detector - Aside from user reviews and cost, determining factors include how well the radar detector, well detects, what frequencies are covered and how many degrees around the car can the detector pick up a signal. Other factors: does it come with a carrying case; can it detect police countermeasures (VG-2); does it have extra feature like the ability for display outside temperature, is there a signal strength meter; does it have escalating levels of brightness; does it have a sensitivity control; i.e. highway or city? Note: as I noted above Ku-band radar guns are used principally in Europe, but they are making their way to U.S. shores, so you may want to make sure your detector covers that band. Some low-end units do not.

IN SUMMARY

Because speeding is so pervasive most law-enforcement officers will look the other way if the offense is not too egregious. But for those of you who insist on topping the speed limit by 15, 20, or even 30 mph, the radar detector is your friend. Since their introduction in 1970's, radar detectors have become a must-have accessory for lead-footed NASCAR wannabes everywhere.

But like everything else in out democratized capitalist society, purchasing the right detector involves choice; make the wise one by doing your research ahead of time. The right radar detector may cost a pound going in, but might save you a ton in speeding ticket fines over its life-span. Not that slowing down to say, under 10mph over the speed limit would not accomplish the same thing, but, hey I think I can remember how fun it is to drive a performance car so by all means open up. But be smart and get a good radar detector that not only covers all of the Doppler radar frequencies, but the LIDAR frequencies as well. And don't forget VG-2, after all radar detectors are illegal in most states and having one can get one fined, or worse - a suspended license.

Find radar detector reviews and price comparisons here.

Here are some other resources as well:
Best Radar Detectors


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