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Guide to Radar & State Troopers
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[ - The Dark Side (312) - 787 - 2174 / Exilic Xyth - Sysop / 24 hours 9600 - ]
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[ - The Modern Speeders Guide to Radar and State Troopers - ]
[ - By : Exilic Xyth - ]
[ - January 11, 1988 - ]
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Introduction:
Touched off by the discussion on Ripco <312>-528-5020, I
found many users asking questions about police radar, radar detectors, and
speeding. With Ron Majors talking about the oil spill that will appear in
detail on the news at ten I thought a informative file on the subject might
be beneficial. I myself had my first experience with police radar in my
fathers car, then following in baseball and my own driving, much more on the
subject. What a fascinating device, that it will return your speed instantly,
what fun one would be to have! After a quick talk with a police friend of
mine, I soon took possession of a used police radar gun.
Part one: Operation.
Police Radar works via the doppler effect, best
demonstrated by sound rather than microwaves. The doppler effect is the
relation of speed to the pitch of 'sound'. Sometime, all of you must have
had the distinct pleasure of being honked at by a motorist on the go,
you might have noticed that the horn <an F flat on most american cars>
begins with a higher pitch and as the car passes, drowns off to a lower
tone. The sound waves at the front of the car are pressed together by the
forward motion of the car, creating a higher pitch. As the car passes,
the tone dies off to a lower pitch because the waves are spread out.
Police radar works in much the same way. The major differences are the
frequency and the concentration of the carrier.
As of 1988, the F.C.C. is rumored to have lifted restrictions
on police radar frequencies. Before, only two frequencies were approved for
police radar use. X-band <10.525 GHz> which is most commonly used, and
K-band <24.15 Ghz>. I will assume for now, due to lack of any SOLID evidence
supporting the restriction lift, that those are the only two in operation.
Police radar 'beams' are similar in shape to a flashlight beam. They begin
with a thin width and cone outwards with distance. Most guns operating at
the X-band level have a range of about 2000 ft., although high power units
can exceed 2500 and 3000ft., and K-band guns fall shorter at about 1200 ft..
At 1500ft., the radar beam becomes about the width of four highway lanes, so
for practical purposes radars range is around 1700 ft.. A radar signal
transmitted from the 'Radar Gun's' transmitter, (called the oscillator) will
bounce off a object and return to the radar receiver (or antenna). If the
object is moving, the frequency of the beam will be altered as it bounces.
This is most easily visualized watching water ripples. Assume now that I
have just dropped a pebble in a pond, and the ripples are moving outward,
assume also for purposes of simplicity that the ripples are moving at
1 foot per second, and that they are one foot apart. The ripples are
therefore also one second apart. Upon bouncing off a stationary object
the ripples will return weakened, but at the same interval and speed
<Not really the same speed, but let's not complicate things>. Now let
us assume that a toy boat is traveling in the water at .5 ft. per second,
1/2 the speed of the ripples, away from the point which I dropped the
pebble. Assume the first ripple has hit the boat and is traveling back.
The second ripple now traveling at 1 foot per second is only gaining on the
boat by .5 feet per second <1 ft. per second - .5 ft. per second>. This means
that the ripple is one foot away from the boat, as the ripples are one foot
apart. The ripple will take 2 second to reach the boat, as the closure speed
is .5 ft. per second and the distance is 1 foot. The ripple strikes the boat
and bounces back two seconds after the first ripple. The process works
inversely for an object moving towards the pebbles point of impact.
As the distance between the ripples can be determined by the speed, on the
other side, the speed can be determined by the distance between the ripples.
Police radar works in the same way with microwaves. The microwave signal
bounces off a moving vehicle and returns altered in frequency. In this way
the radar unit determines the speed of the object. Radar is only accurate
when the object is moving directly at, or directly away from the gun,
although some modern guns will account for this 'COSINE error', most won't.
Cosine error can be defined as this: When a radar signal bounces off an
object at an angle from the objects direction of travel it will return a
portion of the objects speed computed by the cosine of the infraction
angle. If the angle of the objects direction and the radars direction is
20 degrees the speed returned by the radar is 93.97% of the objects
actual speed. cos (20) = .93969262 * objects speed = returned speed.
For example: A car is traveling at 75 m.p.h.. The state trooper, in his
infinite wisdom, decides to "Clock" the automobile in hopes of meeting his
quota for the month. Picking up his handy radar gun, he aims, and fires
an invisible beam of microwave energy. The officer however, being the rookie
he is, leaves a high angle between the cars direction and his beam of 45
degrees. Cos (45) = .707106781 .707106781 * 75m.p.h. = 53.03300859
53 m.p.h. is displayed on the officers screen. Lucky motorist.
Sorry 40 column users.
|
|\
| \
| \ - Cosine Error -
| \
| 45 \
| deg.\ - radar beam
| \
| \
v \
Direction of \
cars travel \
\
X - state trooper.
Part 2: Application
In 1986, over 15 million speeding tickets were issued,
and experts estimate that over 25% of them were in error. Police have
been using radar for speed control for many years, and as the technology
has become more complex and accurate, so has the ability to get away with
the slight infractions of the speed limits set by the government become more
difficult. In recent years, the three most damaging advances to motorists
in radar technology include: A> Instant on radar. B> K-band radar. and
C> Cosine error correcting radar units.
Instant on radar.
With the increase of radar receivers, or
"Detectors" on the roads, police have attempted to bypass the motorists
first line of defense. The most damaging advance in the war against speeding
motorists is instant on radar. The idea behind instant on radar is to make
the radar detector useless to the motorist by making his warning too late to
react to. Instant on radar was developed in early 1983, but never marketed
until late 1984 when the michigan state troopers were equipped with the first
instant on radar guns. It operates by deactivating the oscillator until
triggered by the officer. When used properly and under the right traffic
conditions, it is indefensible. It works like a camera, the officer
operating the radar will position himself behind a blind corner or over a
hill. When the approaching car crests the hill or rounds the corner, the
officer will activate the oscillator, taking a "snapshot" of your car.
As microwaves travel at the speed of light, any attempt at slowing down
is futile, the officer behind the gun has your speed in less than a tenth
of a second.
K-band Radar.
When radar detectors were first marketed by
the markers of ESCORT, there was only one type of radar. X-band.
In an attempt to increase the dwindling speeding ticket revenue, K-band
was brought to life. K-band is a different frequency that could not be
picked up by the primitive detectors of the age. However, as the
frequency got out, the detectors adapted, and now any detector worth a dollar
will detect both X and K bands. K band is more dangerous as most K-band
guns are instant on and they have less 'Splash' and range than X-band guns.
This means that a K-band signal is probably closer to you.
Cosine error correcting guns.
Cosine error was a major falling of radar
in the judicial system, all readings were under question in court, the
result was a gun which will correct for cosine error by determining the
angle which the radar beam "impacts" with the car. Also new in correcting
cosine error were guns with 'Speed lock on' in which the highest speed reading
received by the gun is locked in and displayed.
Moving radar guns.
Until new developments, all radar units
had to remain stationary as radar measures only closure speed, and not actual
speed. Moving radar ended this trend. Moving radar works like this. First
the radar gun determines the patrol cars speed by clocking a sign or fixed
object. The closing speed of the patrol car to the sign is subtracted from
the now taken closing speed to the target car.
Patrols speed - 60 m.p.h.
Closing speed to car - 120 m.p.h.
120 m.p.h. - 60 m.p.h. = 60 m.p.h..
Part 3: Defense
From the dawn of speed enforcement, motorists have sought
to defeat the laws, starting with detectors, continuing to jammers and
topping out with the new 'CHiPs detectors' The unfortunate conditions
now favor the police and law enforcement officials with the introduction
of new radar technologies such as instant on radar.
Detectors:
The simple radar receiver is the first line of
defense from radar. Varied in operation and features, the radar detectors
of today are designed to provide high sensitivity and low rates of false
alarms. Good detectors will measure signal strength and type <K or X>
and have an effective range of about 3000 ft. and a probable range of well
over a mile. Sensitivity tops out around 110.5 dBm/cm^2 for X band and
108 dBm/cm^2 for K band <Both set by the passport>. A detector can give
you an excellent advantage over radar by alerting you it's there. Detectors
become especially useful in chicago where instant on radar is not typically
used.
Jammers:
Radar jammers are essentially units that
transmit microwaves at a frequency dictating a certain speed. The result is
regardless of your speed, the police radar unit will display the speed you
set the jammer to transmit. Jammers are highly illegal and will be
confiscated if discovered, expect a stiff fine.
Chip's detector.
This is a new device, which is really a scanner
on the police radio band. It takes advantage of a signal transmitted by the
patrol cars in some states as part of their dispatch system. The signal
carries for about three miles, and the Chip's Detector will alert you if you
are within that range of a highway patrol unit. It also allows scanning
of police radio channels.
Last words.
Radar is a basically accurate instrument, when used
properly, it can be deadly. As I have said before instant on radar is
impossible to avoid when there is no other traffic around, regardless of
a detector. The only thing that comes close is a Radar Jammer, which
will most likely not serve you well unless it is WELL hidden. Radar
jammers are dangerous with the introduction of the HAWK, a radar unit by
Kustom Signals, which DETECTS radar jammers in the hold mode.
Aside from radar, VASCAR
<Visual average speed computer and recorder>
is a new danger to motorists. It is basically a stopwatch
used to time your movement between two point of which the interval distance
is known. Using the formula Average velocity = distance / time, the state
trooper can determine your speed without setting off your detector.
Instant on radar defense.
The only real defense for instant on radar
is traffic. Traffic will cause the trooper to activate his radar gun more
often, cluing you into his presence. A jammer well hidden will help,
but the best technique is to follow a car making good time. Any police
units in the area will clock him first, and legally they have to ticket him,
unless you're too close.
Remember:
Do not speed, it is a dangerous practice, and I can not be responsible
for any injury, or action due to this file, it is for informational
purposes only. The state troopers enforce speed limits for your
safety.
Radar guns: Models.
Radar guns are manufactured by many different
companies, but the primary ones are Kustom Signals, M.p.h. Industries, and
Decatur.
The deadliest gun now available is the HAWK
manufactured by Kustom Signals. It is the first gun capable of clocking
cars moving the SAME direction as the patrol car. It has two antennas, one
forward, and one back. Like I stated before, it is also the first gun capable
of detecting radar jammers. These run about 2000$
Kr-11
This gun is a two piece model which uses
a weak pulse signal in the moving mode to determine the patrol car's speed
while not triggering detectors. This gun permits a faster clocking time for
instant on moving radar, it runs about $1200
Falcon
This is a hand held gun operating on K band
Small and compact it is preferred among law enforcement radars. It runs about
600$
Hr-4 Hr-8 Hr-12
400,500,750$ respectively, these are hand
held radar guns made by Kustom Signals
All these units are available to you via me
for less than the troopers pay for them. For prices, and statistics,
call my board at (312) - 787 - 2174 or send me mail at Ripco (312) 528-5020
Prices for radar units range from 250-2000$
I personally enjoy harassing that 911
who barrels by at 95 with a detector.
Questions?
The Dark Side:
(312) - 787 - 2174
Ripco
(312) - 528 - 5020
The Courts of Chaos
( My sister board )
(312) - 915 - 0947
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