Radar detector basics

Before you start shopping, you need to know the laws where you drive. Some states and countries have banned radar detectors. If you get caught using a radar detector, it will be confiscated and destroyed. Goodbye, expensive radar detector, and, to add to the financial injury, you may have to pay an extra fine for using one.

To monitor speed, police use a radar gun that emits radio waves on a specified frequency. These waves bounce off your vehicle and return to the gun at a different frequency; the difference between these two frequencies is your speed. Radar detectors sense these radio waves and alert you to their presence.

Police radar guns emit radio signals on one of three frequencies: X, K, or Ka, with Ka being the most widely used today. Newer radar guns operate in POP mode, emitting short bursts of radio waves that are harder to detect. Most radar detectors are able to detect signals on all three frequencies and POP mode, but double-check before you buy, and make sure that your radar detector can detect the entire Ka band; some don’t.

Laser detection and jamming

Since radio waves are emitted over a broad area, they are relatively easy for radar detectors to catch. Police have attempted to thwart radar detectors with laser speed detectors. These devices use light pulses instead of radio waves to measure speed, and they can be focused over a much smaller area.

Almost all radar detectors on the market today include a laser detection feature, but they’re virtually useless. It is illegal throughout the United States to use a device that can detect lasers at distances of more than 1000 feet. Laser light travels at 983 million feet per second, leaving you little chance of slowing down to avoid a ticket. To successfully avoid detection by laser, you need a laser jammer, also known as a blocker or shifter. This device allows you to avoid being detected by making your car invisible to lasers.

While it’s illegal to jam police radar in all states, only a few states have made it illegal to jam lasers. Most radar detectors claim to spot lasers, which they do poorly, but only a few offer laser jamming. If police are using laser speed guns in your area, make sure the radar detector you choose offers laser jamming and look for front and rear or 360-degree protection, as police lasers are effective from all angles, not just the front of your car.

Sensitivity and selectivity

Also called range, sensitivity measures how far ahead a radar detector can sense radio waves. Most budget radar detectors have a range of about a mile, while top-of-the-line units offer ranges of up to three miles. A radar detector with greater sensitivity gives you more time to react.

Some police departments use low-power radar in their ongoing quest to defeat radar detectors. Low-power radar compromises a radar detector’s sensitivity, delaying an alert by as much as 60%. Radar detectors with greater range do a better job of picking up these low-power signals.

Selectivity measures a radar detector’s ability to correctly identify police radar frequencies by filtering out other radio signals it may encounter, such as car alarms or garage door openers, which may cause false alarms. Spending more for a radar detector typically gets you a model with better selectivity.

Radar detector installation

There are two ways to install a radar detector. Dash-mounted radar detectors attach to your dashboard or clip to a visor and draw their power from batteries or your vehicle’s cigarette lighter or power point. Installed radar detectors hide the unit in the body of your vehicle and use sensors mounted in the front and rear to check for radar.

Dash-mounted radar detectors are easy to move from one vehicle to another, but they’re also easy for police to spot. An installed radar detector is harder for police to see, but they require professional installation and it’s essential to set them up so that the radar detector can be removed without damaging or incapacitating your car’s electrical system. Installation is a matter of personal preference, as you’ll find good performance in both dash-mounted and installed radar detectors.

Additional features

Although all radar detectors use a visual alert system, the style and features of the alert can vary. Budget radar detectors may use a simple flashing light to warn of radar, while more sophisticated radar detectors include displays that provide additional information, such as the direction the radar signal is coming from. If you choose a radar detector with a display, look for adjustable brightness for optimum visibility at night or in bright sunlight.

Most radar detectors include an audible alert as well, ranging from simple beeps in lower-priced radar detectors to synthesized voices in more expensive models that tell you the type of radar being used and its direction. If you’ll rely on audible alerts, make sure they’re loud and distinct enough to hear while you’re driving and look for volume adjustments or headphone jacks if you don’t want the radar detector to disturb passengers.

Police in some states can detect radar detectors. VG-2 protection cloaks your radar detector from these devices, either by shielding it from the detection signal or by shutting your radar detector off. Look for this feature if you frequently travel to states where radar detectors are banned, particularly if you have a built-in radar detector.

Need to know more?

• Radar Detector Field Tests
  http://www.speedzones.com
• Radar Detectors
  http://www.prontotech.com/radar-detectors
• Mobile Scanner and Radar Detector Laws in the United States
  http://www.afn.org/~afn09444/scanlaws/