So on a quiet summer night with clear skies a radar unit would pick up a lone truck traveling toward you at a much longer distance that a small car in light rain on a busy day in traffic. Also a fibreglass car such as a Corvette will absorb most of a radar beam until it hits the metal, engine area of the car. Radar picks up the largest, strongest, object, not always in that order. Radar on a multi lane highway usually requires some interpretation of the readings received by the officer therefore although the officer is required to take a required course in the theory and operation of radar experience is important.
Radar Speed Enforcement Radar is speed enforcement using radio waves. What is Police Radar? As radar is a radio wave, the radar beam travels at the speed of light. If the radar gun is used inside a moving police car, its own movement must also be factored in. Factors as weather, rain and snow can affect the ability of the radar unit to send and receive. Demerit Points. Insurance Implications. Licence Suspensions. Fighting Speeding Tickets. Class G Drivers.
G1 Drivers. Types of Enforcement. Here are some of the more common malfunctions and sources of inaccurate readings with radar device:. Many of these defenses are applicable only in certain situations. But, anytime an officer uses a radar to clock a driver's speed, there's the potential for a defense based on inproper calibration. Laser detectors are the most recent addition to the traffic officer's arsenal of speed-measuring devices.
Built to look and act like a hand-held radar gun, a laser detector uses a low-powered beam of laser light that bounces off the targeted vehicle and returns to a receiver in the unit. The unit then electronically calculates the speed of the targeted vehicle. Laser detectors are supposedly more accurate than radar units. One advantage for police officers of the laser gun is that the light beam is narrower than a radar beam, meaning that it can be more precisely aimed.
This is true even though laser detectors use three separate beams, because the combined width of the three beams is still much narrower than a single radar beam at the same distance.
This technology reduces, but does not eliminate, the chance that the speed of a nearby car will be measured instead of the speed of the car at which the operator aims the gun. Laser detectors measure distance between the gun and the target car using the speed of light and the time it takes the light, reflected off the target vehicle, to return to the laser gun. The detector makes about 40 of these distance measurements over a third of a second, then divides the light's round-trip distance by the time, to get the speed.
This means to be accurate the officer must hold the combined beams on the same part of the car during the test. While this is easier to do with radar because of its wide beam, it is tricky to do this with a narrow laser beam.
Also, it's impossible to be sure that that the officer has been able to accomplish this feat because the officer can't see the beam. It's also possible especially in heavy traffic for one beam to hit the target car and another beam to hit a nearby car. The chances of this happening increase with traffic density and the distance between the laser unit and the measured vehicle. The information provided on this site is not legal advice, does not constitute a lawyer referral service, and no attorney-client or confidential relationship is or will be formed by use of the site.
The attorney listings on this site are paid attorney advertising. In some states, the information on this website may be considered a lawyer referral service. Please reference the Terms of Use and the Supplemental Terms for specific information related to your state. Grow Your Legal Practice. Meet the Editors. If you want to fight your ticket, you should find out how your speed was determined. If you want to fight a speeding ticket, there are two things you must know first: whether you charged under an "absolute," "presumed," or "basic" speed law how the officer measured your speed —through pacing, aircraft, radar, laser, VASCAR, or other means.
Pacing Many speeding tickets result from the police officer following or "pacing" a suspected speeder and using his or her own speedometer to clock the suspect's speed.
Here are some things to consider for fighting a speeding ticket based on pacing: Road configuration may help prove inadequate pacing. Hills, curves, traffic, interchanges, traffic lights, and stop signs can all help you prove that an officer did not pace you long enough. For example, an officer following your vehicle a few hundred feet behind will often lose sight of it through a curve. Similarly, if you were ticketed within feet of starting up from a stop sign or light, it could case into doubt whether the officer can prove having paced your car for a reasonable distance.
The farther back the officer, the less accurate the pace. For an accurate "pace," the officer must keep an equal distance between the patrol car and your car for the entire time of the pacing. The officer's speedometer reading, after all, means nothing if the officer is driving faster than you are in an attempt to catch up. To avoid this problem, officers are trained to "bumper pace" your car by keeping a constant distance between the patrol car's front bumper and your rear bumper.
Bumper pacing becomes more difficult the farther behind the officer is from your car. The most accurate pace occurs where the officer is right behind you. But patrol officers like to remain some distance behind a suspect to avoid alerting a driver who periodically glances at the rearview and side-view mirrors. So if you know an officer was close behind you for only a short distance, your best tactic in court is to try to show that the officer's supposed "pacing" speed was really just a "catch-up" speed.
Pacing at dusk or nighttime. Pacing is much more difficult in the failing light of dusk or in complete darkness, unless the officer is right on your tail. In the darkness, the officer's visual cues are reduced to a pair of taillights. Also, if an officer paces a speeder's taillights from far back in traffic, he or she might have trouble keeping the same pair of taillights in view.
Aircraft Speed Detection There are two ways an aircraft officer determines your speed. Here are some things to consider for fighting an aircraft speeding ticket: Ask for dismissal if either officer fails to appear.
If both officers are not in court, ask the judge to dismiss the case. If the prosecution tries to introduce an absent officer's police report or other written record into court in place of live testimony, simply object on the basis that it is hearsay. Without an officer present, the written report is inadmissible hearsay testimony. Stopwatch and reaction-time error. If the officer's timing is not performed properly from the aircraft, the speed measurement of your vehicle won't be accurate.
Since this speed is calculated by dividing distance by time, the shorter the distance your speed was measured over, the more likely it is that a timing error will result in a too-high speed reading.
For example, if the officer hesitated even slightly before pushing the timer as you passed the first ground marker, the measured time would be shorter than the true time your vehicle took to traverse the distance to the second marker.
Difficulty in keeping your car in view. If two markers are a mile apart, it takes a car doing 75 miles per hour about 48 seconds to travel between the two markers. It's hard to stare continuously at anything for that long, especially from a plane. If many other cars are on the road, it would be easy for the sky officer to lose sight of your car while looking at the flight instruments.
In simple terms, a radar gun transmits a narrow beam of radio-frequency energy out the front of the gun and looks for that signal to be reflected back to the gun after bouncing off an object.
Unlike lidar and laser guns , the speed measurement is calculated by how much the received signal has changed in frequency after reflecting off the moving object. This phenomenon is called a Doppler effect and is the same reason that a car sounds different as it approaches and drives away from you.
Imagine that you have a tennis ball machine shooting balls at a stationary object once every second. The balls bounce back to the machine and arrive once per second.
If you start to move the object toward the ball launching machine, the balls bounce back faster and faster as the object approaches the machine. This increase in return speed represents an increase in frequency.
If an object is moving away from the tennis ball machine, it will take longer for each ball to bounce back, thus representing a decrease in frequency. The digital signal processor in modern radar guns is configured to analyze the changes in the reflected signal very quickly and display a speed reading in less than a second. In North America, police officers use radar guns that operate in the X, K and Ka band frequency ranges. X band radar is prone to interference from automatic door opening systems.
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