270 lines
15 KiB
Plaintext
270 lines
15 KiB
Plaintext
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[ - The Modern Speeders Guide to Radar and State Troopers - ]
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[ - By : Exilic Xyth - ]
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Introduction:
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Touched off by the discussion on Ripco <xxx>-xxx-5020, I
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found many users asking questions about police radar, radar detectors, and
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speeding. With Ron Majors talking about the oil spill that will appear in
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detail on the news at ten I thought a informative file on the subject might
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be beneficial. I myself had my first experience with police radar in my
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fathers car, then following in baseball and my own driving, much more on the
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subject. What a fascinating device, that it will return your speed instantly,
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what fun one would be to have! After a quick talk with a police friend of
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mine, I soon took possession of a used police radar gun.
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Part one: Operation.
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Police Radar works via the doppler effect, best
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demonstrated by sound rather than microwaves. The doppler effect is the
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relation of speed to the pitch of 'sound'. Sometime, all of you must have
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had the distinct pleasure of being honked at by a motorist on the go,
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you might have noticed that the horn <an F flat on most american cars>
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begins with a higher pitch and as the car passes, drowns off to a lower
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tone. The sound waves at the front of the car are pressed together by the
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forward motion of the car, creating a higher pitch. As the car passes,
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the tone dies off to a lower pitch because the waves are spread out.
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Police radar works in much the same way. The major differences are the
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frequency and the concentration of the carrier.
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As of 1988, the F.C.C. is rumored to have lifted restrictions
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on police radar frequencies. Before, only two frequencies were approved for
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police radar use. X-band <10.525 GHz> which is most commonly used, and
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K-band <24.15 Ghz>. I will assume for now, due to lack of any SOLID evidence
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supporting the restriction lift, that those are the only two in operation.
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Police radar 'beams' are similar in shape to a flashlight beam. They begin
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with a thin width and cone outwards with distance. Most guns operating at
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the X-band level have a range of about 2000 ft., although high power units
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can exceed 2500 and 3000ft., and K-band guns fall shorter at about 1200 ft..
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At 1500ft., the radar beam becomes about the width of four highway lanes, so
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for practical purposes radars range is around 1700 ft.. A radar signal
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transmitted from the 'Radar Gun's' transmitter, (called the oscillator) will
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bounce off a object and return to the radar receiver (or antenna). If the
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object is moving, the frequency of the beam will be altered as it bounces.
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This is most easily visualized watching water ripples. Assume now that I
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have just dropped a pebble in a pond, and the ripples are moving outward,
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assume also for purposes of simplicity that the ripples are moving at
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1 foot per second, and that they are one foot apart. The ripples are
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therefore also one second apart. Upon bouncing off a stationary object
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the ripples will return weakened, but at the same interval and speed
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<Not really the same speed, but let's not complicate things>. Now let
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us assume that a toy boat is traveling in the water at .5 ft. per second,
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1/2 the speed of the ripples, away from the point which I dropped the
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pebble. Assume the first ripple has hit the boat and is traveling back.
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The second ripple now traveling at 1 foot per second is only gaining on the
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boat by .5 feet per second <1 ft. per second - .5 ft. per second>. This means
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that the ripple is one foot away from the boat, as the ripples are one foot
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apart. The ripple will take 2 second to reach the boat, as the closure speed
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is .5 ft. per second and the distance is 1 foot. The ripple strikes the boat
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and bounces back two seconds after the first ripple. The process works
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inversely for an object moving towards the pebbles point of impact.
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As the distance between the ripples can be determined by the speed, on the
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other side, the speed can be determined by the distance between the ripples.
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Police radar works in the same way with microwaves. The microwave signal
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bounces off a moving vehicle and returns altered in frequency. In this way
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the radar unit determines the speed of the object. Radar is only accurate
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when the object is moving directly at, or directly away from the gun,
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although some modern guns will account for this 'COSINE error', most won't.
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Cosine error can be defined as this: When a radar signal bounces off an
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object at an angle from the objects direction of travel it will return a
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portion of the objects speed computed by the cosine of the infraction
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angle. If the angle of the objects direction and the radars direction is
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20 degrees the speed returned by the radar is 93.97% of the objects
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actual speed. cos (20) = .93969262 * objects speed = returned speed.
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For example: A car is traveling at 75 m.p.h.. The state trooper, in his
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infinite wisdom, decides to "Clock" the automobile in hopes of meeting his
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quota for the month. Picking up his handy radar gun, he aims, and fires
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an invisible beam of microwave energy. The officer however, being the rookie
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he is, leaves a high angle between the cars direction and his beam of 45
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degrees. Cos (45) = .707106781 .707106781 * 75m.p.h. = 53.03300859
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53 m.p.h. is displayed on the officers screen. Lucky motorist.
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Sorry 40 column users.
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| \
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| \ - Cosine Error -
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| 45 \
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| deg.\ - radar beam
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v \
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Direction of \
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cars travel \
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\
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X - state trooper.
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Part 2: Application
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In 1986, over 15 million speeding tickets were issued,
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and experts estimate that over 25% of them were in error. Police have
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been using radar for speed control for many years, and as the technology
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has become more complex and accurate, so has the ability to get away with
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the slight infractions of the speed limits set by the government become more
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difficult. In recent years, the three most damaging advances to motorists
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in radar technology include: A> Instant on radar. B> K-band radar. and
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C> Cosine error correcting radar units.
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Instant on radar.
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With the increase of radar receivers, or
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"Detectors" on the roads, police have attempted to bypass the motorists
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first line of defense. The most damaging advance in the war against speeding
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motorists is instant on radar. The idea behind instant on radar is to make
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the radar detector useless to the motorist by making his warning too late to
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react to. Instant on radar was developed in early 1983, but never marketed
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until late 1984 when the michigan state troopers were equipped with the first
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instant on radar guns. It operates by deactivating the oscillator until
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triggered by the officer. When used properly and under the right traffic
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conditions, it is indefensible. It works like a camera, the officer
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operating the radar will position himself behind a blind corner or over a
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hill. When the approaching car crests the hill or rounds the corner, the
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officer will activate the oscillator, taking a "snapshot" of your car.
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As microwaves travel at the speed of light, any attempt at slowing down
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is futile, the officer behind the gun has your speed in less than a tenth
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of a second.
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K-band Radar.
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When radar detectors were first marketed by
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the markers of ESCORT, there was only one type of radar. X-band.
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In an attempt to increase the dwindling speeding ticket revenue, K-band
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was brought to life. K-band is a different frequency that could not be
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picked up by the primitive detectors of the age. However, as the
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frequency got out, the detectors adapted, and now any detector worth a dollar
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will detect both X and K bands. K band is more dangerous as most K-band
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guns are instant on and they have less 'Splash' and range than X-band guns.
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This means that a K-band signal is probably closer to you.
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Cosine error correcting guns.
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Cosine error was a major falling of radar
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in the judicial system, all readings were under question in court, the
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result was a gun which will correct for cosine error by determining the
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angle which the radar beam "impacts" with the car. Also new in correcting cosine error
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were guns with 'Speed lock on' in which the highest speed reading
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received by the gun is locked in and displayed.
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Moving radar guns.
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Until new developments, all radar units
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had to remain stationary as radar measures only closure speed, and not actual
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speed. Moving radar ended this trend. Moving radar works like this. First the radar
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gun determines the patrol cars speed by clocking a sign or fixed
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object. The closing speed of the patrol car to the sign is subtracted from
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the now taken closing speed to the target car.
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Patrols speed - 60 m.p.h.
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Closing speed to car - 120 m.p.h.
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120 m.p.h. - 60 m.p.h. = 60 m.p.h..
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Part 3: Defense
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From the dawn of speed enforcement, motorists have sought
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to defeat the laws, starting with detectors, continuing to jammers and
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topping out with the new 'CHiPs detectors' The unfortunate conditions
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now favor the police and law enforcement officials with the introduction
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of new radar technologies such as instant on radar.
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Detectors:
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The simple radar receiver is the first line of
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defense from radar. Varied in operation and features, the radar detectors
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of today are designed to provide high sensitivity and low rates of false
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alarms. Good detectors will measure signal strength and type <K or X>
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and have an effective range of about 3000 ft. and a probable range of well
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over a mile. Sensitivity tops out around 110.5 dBm/cm^2 for X band and
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108 dBm/cm^2 for K band <Both set by the passport>. A detector can give
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you an excellent advantage over radar by alerting you it's there. Detectors
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become especially useful in chicago where instant on radar is not typically
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used.
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Jammers:
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Radar jammers are essentially units that
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transmit microwaves at a frequency dictating a certain speed. The result is
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regardless of your speed, the police radar unit will display the speed you
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set the jammer to transmit. Jammers are highly illegal and will be
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confiscated if discovered, expect a stiff fine.
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Chip's detector.
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This is a new device, which is really a scanner
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on the police radio band. It takes advantage of a signal transmitted by the
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patrol cars in some states as part of their dispatch system. The signal
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carries for about three miles, and the Chip's Detector will alert you if you
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are within that range of a highway patrol unit. It also allows scanning
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of police radio channels.
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Last words.
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Radar is a basically accurate instrument, when used
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properly, it can be deadly. As I have said before instant on radar is
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impossible to avoid when there is no other traffic around, regardless of
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a detector. The only thing that comes close is a Radar Jammer, which
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will most likely not serve you well unless it is WELL hidden. Radar
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jammers are dangerous with the introduction of the HAWK, a radar unit by
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Kustom Signals, which DETECTS radar jammers in the hold mode.
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Aside from radar, VASCAR
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<Visual average speed computer and recorder>
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is a new danger to motorists. It is basically a stopwatch
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used to time your movement between two point of which the interval distance
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is known. Using the formula Average velocity = distance / time, the state
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trooper can determine your speed without setting off your detector.
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Instant on radar defense.
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The only real defense for instant on radar
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is traffic. Traffic will cause the trooper to activate his radar gun more
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often, cluing you into his presence. A jammer well hidden will help,
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but the best technique is to follow a car making good time. Any police
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units in the area will clock him first, and legally they have to ticket him,
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unless you're too close.
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Remember:
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Do not speed, it is a dangerous practice, and I can not be responsible
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for any injury, or action due to this file, it is for informational
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purposes only. The state troopers enforce speed limits for your
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safety.
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Radar guns: Models.
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Radar guns are manufactured by many different
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companies, but the primary ones are Kustom Signals, M.p.h. Industries, and Decatur.
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The deadliest gun now available is the HAWK
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manufactured by Kustom Signals. It is the first gun capable of clocking
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cars moving the SAME direction as the patrol car. It has two antennas, one
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forward, and one back. Like I stated before, it is also the first gun capable
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of detecting radar jammers. These run about 2000$
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Kr-11
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This gun is a two piece model which uses
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a weak pulse signal in the moving mode to determine the patrol car's speed
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while not triggering detectors. This gun permits a faster clocking time for
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instant on moving radar, it runs about $1200
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Falcon
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This is a hand held gun operating on K band
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Small and compact it is preferred among law enforcement radars. It runs about
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600$
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Hr-4 Hr-8 Hr-12
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400,500,750$ respectively, these are hand
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held radar guns made by Kustom Signals
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All these units are available to you via me
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for less than the troopers pay for them. For prices, and statistics,
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call my board at (xxx) - xxx - 2174 or send me mail at Ripco (xxx) xxx-5020
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Prices for radar units range from 250-2000$
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I personally enjoy harassing that 911
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who barrels by at 95 with a detector.
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Questions?
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The Dark Side:
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(xxx) - xxx - 2174
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Ripco
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(xxx) - xxx - 5020
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