How does police radar work? A police radar gun operates by transmitting radio waves at certain frequencies which reflects off objects (your vehicle) and are then picked up by the radar gun's receiving section. When radar waves reflect off a moving target, a measurable frequency shift occurs. The radar unit converts this shift into miles per hour to determine the target's speed. Two basic types of radar are used - stationary and moving. Stationary radar must be used from a static site, typically a patrol car parked along side the road |
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(See above figure). But with a single antenna moving radar, an officer can clock approaching vehicles while driving on patrol. Moving radar with two antennae - one facing forward, the other aimed out the back of the cruiser - can also clock vehicles even after they have passed by, headed in the opposite direction. How does a radar detector work? A detector is a radio receiver tuned to specific frequencies used by police radar. It is extremely sensitive, often able to hear radar from over a mile away, far beyond the range at which radar can clock a vehicle's speed. In evaluating a detector, the two most important performance criteria are sensitivity and selectivity. Sensitivity is a measure of a units detection range. Selectivity refers to a unit's ability to reject non-police microwave signals and is an important feature because of the many sources of "electronic pollution". Note: Automatic door openers and some burglar alarms operate on X-band, which is a police band. A radar detector cannot tell if a store is opening a door or a police officer is checking speed. |
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Why are radar detectors described as dual band, triband, wideband or superwideband? Early detectors needed only to listen for X band radar. When K band arrived, dual band models able to receive both frequencies (X and K) were required. The introduction of Ka band photo radar (34.3 GHz) led to the development of triband models able to detect X, K, plus a small portion of Ka band. A fourth category of radar receivers called wideband, with X, K and "wideband" Ka (34.2 - 35.2 GHz) detection capabilities reached the market following the introduction of Stalker radar. And finally, in response to the BEE 36A a new generation of radar detectors were developed termed superwideband, which cover all radar guns operating on X, K or "superwideband" Ka (33.2- 36.0 GHz). What frequencies are used? Except for a few early units, X band (10.525 GHz) was the only frequency used for police radar until the mid 1970's. In 1976 radar guns using K band (24.150 GHz) were introduced; this led to the development of the first dual band (X/K) radar detectors. A proliferation of radar guns using Ka band frequencies began in 1987 with the introduction of photo radar (34.3 GHz) and was followed by the Stalker (34.2 - 35.2 GHz) in 1991 and the BEE 36A (33.4-34.4 GHz) in 1992. What is a false alert? A number of transmitting devices are also allowed to operate on the same frequencies used by police radar. These are not considered false signals. For example, the automatic door openers commonly used by businesses are low powered X band transmitters. They produce signals that appear legitimate to a radar detector and cause it to alarm. Other sources produce "harmonics" signals, ghosts or look alike K or Ka band radar signals which make a radar detector give a false alert. A better radar detector reduces these types of false alarms. What is "POP", "instant on" or "pulse" Radar? When radar detectors proved easily capable of sniffing out radar from miles away, radar gun manufacturers responded by producing instant-on radar or unoffically called "Pulse" radar. In the instant-on mode, the radar's transmitter is placed on hold, ready to fire but not yet producing a signal for detectors to hear. The officer waits until his target is very close (brings a new meaning to "wait till you see the whites of their eyes") then releases the radar from stand by mode and gets a speed reading within a second or so (pulse). In this situation, no detector offers much warning. Instant-On radar just took on a whole new meaning in 2003! There are new guns out there that operate just like the instant-on guns of the past but with a very tough new twist - POPTM mode! This new gun is a normal K and Ka band radar gun detectable by most radar detectors made in the past 30 years, until this gun is placed in POP mode. When the gun is in POP™ Mode and activated, a brief burst of energy, less than 1/15 of a second, is transmitted and the vehicle's speed is quickly acquired. A detector without POP™ Mode detection capability cannot respond to this brief transmission. Whistler models, 1758, 1773, 1776, 1778, 1783, 1788 1793SE, XTR SERIES (Except XTR-105, 140, 260) and all PRO Series have POP mode detection capabilities! How do laser speed detectors work? Laser speed guns transmit short bursts of invisible light which bounce off a target vehicle and return to the laser gun. By timing the outgoing and return trips of the light bursts, it can compute the target's speed. The laser's biggest selling point is its narrow beam-only about three feet wide at a distance of 1,000 feet - a feature that provides nearly foolproof target identification. (In comparison, a radar's beam is about 250 feet wide at 1,000 feet.) Laser guns must be used from stationary position and are most effective at short range, usually when targeting traffic at 600 to 1,200 feet. How does a laser detector work?
Since laser guns use a specific light frequency, or wavelength, it is possible to detect a laser's signature light pulse rates. Different laser guns operate at different light pulse rates. Some competitors call them "bands". All Whistler radar/laser detectors receive all current laser guns in use, these include; Keep in mind that laser detectors act differently than radar detectors. Since the narrow laser beam produces very little "scatter"- random bits of electromagnetic energy bouncing down the road -it is much harder to detect than a powerful radar gun that blankets the countryside with easily detectable microwave signals. Laser guns operate exclusively in instant-on mode and usually target vehicles at short range. Similar to instant on radar, if you are the target vehicle don't expect much warning. The result is your laser detector usually will offer less advance warning because at 1000 feet the beam is only 3 feet wide and that the officer aims at your license plate or headlights. The distance from where your detector is mounted to the license plate can be greater than 3 feet. This will be outside of the laser beam. If the officer is not steady while targeting vehicles, scatter laser signals can result, giving a possible signal to detect. Are detectors Legal? Laser detectors are completely legal in every state when used in automobiles or light trucks (under 10,000 lbs.). Similarly, when used in automobiles or light trucks, radar detectors are legal in almost every state. Exceptions are Virginia and Washington DC, which have local regulations restricting the use of radar receivers in any vehicle. Concerning trucks over 10,000 lbs., the Federal Highway Administration (FHwA) issued a regulation, effective January 19, 1994, which prohibits nationally radar and laser detector use in
Prior to the FHWA regulation, laws existed in the state of New York restricting the use of radar detectors in trucks over 18,000 lbs... and in Illinois in trucks over 26,000 lbs. These laws remain in effect. In Canada, radar detectors and laser detectors are illegal to use in Manitoba, New Brunswick; Newfoundland, Ontario, Prince Edward Island, and Quebec. NOTE: It is the responsibility of the individual radar detector owner to know the laws in your area regarding the legality of the use of laser/radar detectors. Many detectors have a stay alert feature and they all work similarly. This is how the Whistler stay alert feature works.
The Stay Alert feature is designed to test a driver's alertness. Within 30 to 60 seconds after the feature is engaged an alert is sounded; to show alertness, the driver must press the volume, city or the mute button within 3-5 seconds. If a button is pressed within 3-5 seconds, the cycle is repeated. If a button was not pressed within 3-5 seconds the unit alarms at full volume and the display shows an unique visual alert. WARNING! Stay Alert is NOT intended as a substitute for adequate rest. You should NOT operate a vehicle if you are drowsy. During extended periods of vehicle operation, you should take frequent breaks. Improper reliance on the Stay Alert feature may result in vehicle damage, personal injury or death. NEVER OPERATE A VEHICLE IF YOU ARE DROWSY.
MAY YOUR NEXT TRIP BE RED LIGH TFREE AND EASILY FOUND Thank you for your time E & B Enterprises |
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