Type of detector: There are three types of radar detector: corded, cordless, and remote-mount. Corded detectors usually mount on the windshield via suction cups, and provide the best range of detection. Cordless detectors are transported easily between vehicles, and provide a cleaner installation than corded models. Remote-mount detectors are permanently mounted to your vehicle, providing a clean installation that's virtually undetectable by thieves.
City Modes: City mode turns down the range or sensitivity so that you get fewer false alerts; this feature is helpful for urban driving.
Laser detection : A detector with one laser sensor can detect laser beams in front of you, but not behind you or off to the sides. 360-degree laser detection uses two sensors to look for laser pulses to the sides and behind you. Models with 360-degree laser detection tend to be more reliable, but more costly.
VG-2 and Specter protection: These are shielding technologies that let you know when police are using radar detector detectors (RDD). Specter is a more advanced RDD technology that is currently being used in several states and Canada. Some detectors offer Stealth protection, which warns you and then shuts down the detector, while more expensive detectors offer Invisible protection - they may be shielded from VG-2, Specter, or both, so they can continue operating without being discovered.
Digital voice alerts: A voice alert tells you what your radar detector has picked up. You don't have to take your eyes off of the road to look at the detector's display.
"Instant-On" Protection : Practically speaking, you can't really defend yourself against Instant-On radar; if it's been aimed at you, your speed has been measured by the time your detector gives an alert. However, if the radar was targeted on a car ahead of you, a detector with sensitive K-band reception will alert you. High K-band sensitivity is what allows manufacturers to promote a detector as giving Instant-On Protection.
RADAR DETECTORS: TREAT YOURSELF TO PEACE OF MIND The freedom to relax and drive with confidence - that's what an investment in a radar detector can give you. Today's models combine simple, ergonomic design with up-to-the-minute technology. They can offer you affordable, convenient protection, not only from speeding tickets but often from driving hazards, as well.
HOW RADAR DETECTOR WORK Think of a radar signal as a beam of light from a flashlight. When you shine a flashlight at an object, your eyes perceive the light reflected from the object. Now imagine yourself as the object being illuminated. You can see the light from the flashlight from a much farther distance than the person with the flashlight could ever hope to see you. That's because the beam loses energy over distance. So while the beam has enough energy to reach you, the reflected light doesn't have enough energy to travel all the way back to where it started.
Police radar guns "see" a vehicle by transmitting a microwave pulse. Then they make use of the Doppler Effect: the frequency of the transmitted pulse is compared to the frequency of the reflection, and speed is calculated by using the difference between them.
Speed is calculated when a pulse is reflected to the RADAR transmitter. That's the idea behind radar detectors. They look for radar "beams" and find them before they can return a strong enough reflection to "illuminate" you. Radar detectors use something called superheterodyne reception to accomplish this. Radar detectors are essentially microwave radio receivers that make noise or flash lights when they sense an incoming signal on specific frequencies. Superheterodyne reception allows detection of radar around curves or over hills, and it extends detection range straight ahead.
DIFFERENT TYPES OF RADAR The Federal Communications Commission has dictated that police radar must operate on specific frequency bands:
X-BAND RADAR: 10.5 - 10.55 GHZ Dating from the 1950s, X-band radar is the easiest to detect because of its lower frequency and higher power output. Depending on terrain, temperature and humidity, X-band radar can be detected from a distance of 2 to 4 miles, yet it can only take accurate readings of speed from a distance of 1/2 mile or less. Unfortunately, police radar is not the only source of X-band signals. Garage door openers, microwave intrusion alarms, microwave towers, and other high-tech equipment can fool a radar detector into giving off an X-band alert. Filters and redundant sampling are used to combat this "falsing."
K-BAND: 24.05 - 24.25 GHZ K-band, the most common type of police radar, made its appearance in 1978. The first K-band hand-held radar guns could only be used from a stationary position. Later, a "pulsed" version was introduced that could be used from a stationary or moving vehicle. K-band radar waves have a relatively small wavelength and so are more easily absorbed by water molecules in the air. At the power level found in police radar guns, K-band has an effective clocking range of about 1/4 mile. Depending upon terrain (around a corner, over a hill, etc.), K-band waves can be detected from a range of 1/4 to 2 miles.
K-band guns also have what's known as "Instant-On" radar. This is basically a kill-switch option which keeps the transmitter in "hot standby" mode, ready to be activated by an officer when the target is within 200-300 yards. If it's been aimed at you, your speed has been measured by the time the detector alerts you. If it is being used to target vehicles ahead of you, your detector may provide a warning in time for you to adjust your speed.
VG-2 AND SPECTER RDD In some localities, it's illegal to use a radar detector, and many areas have regulations against using detectors in commercial vehicles. Therefore, police have developed "radar detector detectors," referred to as RDD. These devices pick up oscillations emitted by the receivers in radar detectors, and inform police that a radar detector is being used. Many manufacturers now have models that are specially shielded to eliminate most of these emissions, or will shut down when they detect a RDD system in use.
VG-2 is a common type of RDD technology, and it works by detecting the oscillations on a single frequency band. Most detectors today are built to protect themselves from VG-2 detection, but a newer type of RDD technology, known as Specter, has proven more difficult to circumvent. This is because Specter operates on several frequency bands and can pick up more emissions from a radar detector. There are detectors on the market now which do offer Specter invisibility.
LASER RADAR DETECTORS Laser speed guns determine speed differently than radar guns. A series of light pulses is transmitted, and the difference in time between pulses and reflections is used to calculate speed. This all takes place very rapidly (at the speed of light, as a matter of fact). A single pulse typically requires only a few nanoseconds to transmit and return. The advantages of a laser gun are compelling: the laser light beam is far narrower than a radar beam, allowing more accurate pinpointing of a specific vehicle; and the total time needed for capturing a speed reading is less than half a second versus 2 to 3 seconds for radar.
The drawbacks are also important to note: laser guns are very expensive, they can't be used from a moving vehicle or from behind glass, and accurate aiming requires a tripod or a very steady hand. Despite initial claims to the contrary, a laser gun is detectable. And as the laser beam moves away from the laser gun, it widens and becomes even easier to detect. Vehicle speeds are typically measured at roughly 1,000 feet (1/5 mile); at that distance the laser beam is over 3 feet wide. Many of the laser radar detectors in use have a working distance of approximately 1-1/2 miles (at that distance a laser gun's beam covers two lanes of traffic).
FACTORS AFFECTING RANGE According to a Car & Driver study, a significant loss in detection range occurs when vehicles contain windshields with metallic film embedded, and when commercially available tint films are applied.
Radar detection range is most affected by windshields with metallic film solar-barrier treatments, found in Ford products with Instaclear windshields, GM products with PPG and Everclear windshields, and in some high-end imports. In these vehicles, detection capability drops by a startling 95 percent!
Laser detection range is always affected by glass, sometimes losing up to 80% of its sensitivity. It's also affected by tint films - the darker the tint, the more loss. Some tint films contain a metallic layer, and these can reduce radar detection capability by as much as 37 percent.
RADAR WITH GPS Recent developments in GPS technology have empowered radar detectors with more functionality than ever before. GPS stands the global positioning system, a satellite network that communicates with devices to assist in ground-based navigation applications. GPS devices in cars communicate with satellites while moving. These devices measure speed, location, and direction down to a few feet. They can often also store location information to mark important points on the map.
GPS radar detectors can calculate where they are and how fast they're going at any time while they are communicating with the GPS network. This is a powerful advantage over normal radar detectors because even though they can tell you when radar is in use around you, they have no way of knowing how fast your vehicle is traveling.
Some GPS detectors can adjust their sensitivity depending on how fast the vehicle is going, which reduces the need to manually switch between city and highway modes. They can also alert you when you are traveling over a set speed limit for your own safety.
Some GPS radar detectors can be programmed to "remember" areas that you drive past and alert you when they are approaching. If you drive past an area with a suddenly steep drop in the speed limit, the detector can warn you ahead of time so you can adjust your driving accordingly. Or you can program it to remind you of areas where there are red light or speed cameras or frequent speed patrols.
This information has been provided by Robert Ferency-Viars - Jun 16, 2003
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