How is radar used to determine the speed of a car?


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2012-05-08 22:08:41
2012-05-08 22:08:41

A beam of electromagnetic waves is bounced off the car

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It measures the time it takes for the radar pulse to go from the radar gun to your vehicle and back. The pulse is fairly constant so the radar gun is getting updates and by comparing the updates to the time it can determine speed.

An anemometer is used to measure wind speed. A Pitot Tube is used to infer speed in an aeroplane,. A speedometer in an ordinary car, and a microwave or laser radar in a Police car.

A speed gun is a handheld Radar or Laser unit used by traffic police to check how fast a car is going.

Doppler Radar uses the Doppler effect to determine speed toward or away from the Radar. When a Radar return has a higher frequency than the transmitted pulse, the object is coming closer, and the *difference in frequency determines speed. Lower frequency- object is moving away. This is used by police, and for weather Radar to help detect not only speed but to detect patterns characteristic of tornadoes. Also used for other applications not just military. You are your own Doppler system using audible frequencies. You can tell when a car, plane, or train is approaching vs moving away.

Yes. The radar calculating unit is reading more than one speed. It reads the patrol car speed from stationary objects (the ground, signs, etc.) and subtracts that speed from the speed at which your car and his car are coming together. If the patrol car is doing 38 and you are doing 55, the radar unit will read 38 from the ground and 93 from your car. It subtracts the 38 from the 93 and displays your speed as 55.

-thermometer -measuring the speed of the car "radar"

No, if you are moving 30 mph and another car is too, the radar would say the car is going 0 mph. depends on where you are... in some areas yes Thats the idea, radar guns are used to check a vehicles speed, if you mean can a radar gun be used from a moving vehicle then no, the gun must be stationary otherwise an inaccurate reading will result.

Having a radar detector will alert you when a Police Car with its speed radar is near. The Radar Detectors will produce an audible signal alerting you of this, and will do so far in advance of when you are able to see the Police Car.

The frequency of the radar signal does not change. Be it a cop getting you speed, or a modern car with Brake assist (they use a radar signal to assist keeping a safe distance) it's all timing, how long from the radar source to return to source. If a police car is still, and you are moving away, the increase in return of signal time tells the computer in the officer's car your speed. Even if you are going toward each other, the computer knows the speed of the officer's car and again, signal return time factored in with speed of cop car the computer can give an instant, real-time speed.

No. With police officers in motion, it would appear that cars would be going slower. Say that a car is going 50 MPH, and you are going 45 MPH. Eventually the vehicle wil be ahead of you. Now say you are a police officer with radar. If you test this car, it will appear (on radar) that the 50 MPH car is only going 5 MPH, thus to get the accurate speed, you must be going 0 MPH.Disagree. The original police radar required a stationary unit. Radar is use for the past 30 years is capabable of adding or deducting the speed of the police car from the observed speed. It does not require that the police car be in one fixed spot.Added: The second cotributor is correct. I seriously doubt that any of the old radar units are still in operation much less certifiable as accurate. ALSO: the term "radar" is a commonly used by the the public to describe ALL police speed-clocking devices. Any of these can be calibrated to be used while the vehicles are in motion.

um radar guns emit radiation ........they use the radar guns to find the speed of a speeding car.

oh yes, the radar guns are attached to the cars internal computers, so it compensates for the forward speed.

Look at the speedometer.

The answer is "yes." Traffic radar monitors both the speed of the vehicle in which is it mounted and the speed of "target" vehicles coming toward or moving away from it. On the radar display, the officer sees two speeds: "patrol" (the speed of his vehicle) and "target" (the speed of the vehicle the radar is tracking). the target speed measurement is equally accurate, whether the patrol vehicle is moving or not.

idon't know about the speedometer reading but the speed the radar gun is the same as the relative movement of the vehicle not the speed at which the tires revolve

You can measure the speed of remote control car using a speedometer,GPS or radar gun. For more information check out

The Doppler effect can be used with a radar gun. Police can use this device to detect drivers who are traveling above the speed limit. The radar gun emits a radio signal with a known wavelength. A moving car generates a returning wave whose wavelength is picked us be the radar gun. The size of the difference in the two wavelengths shows how fast the moving vehicle is traveling.

A RADAR gun is typically used by police to measure the speed of an auto. Using stop watches to measure the elapsed time over a known distance would also give the average speed. A dynamometer can also be used to measure tire rotation in a stationary situation and be converted to an equivalent speed.

Of course they can all they have to do is hold the radar gun with one hand and the wheel with the other

we can find the speed of moving car by using micro waves.these waves fall on the moving car and get reflected back whose wavelength is recorded by a device attached to the computer. and finally we can determine the speed of the car.

Radar, lasers, visual references against timing (either from the ground or from the air)

Often times it is difficult to determine the value of a used car on the spot. I would suggested using car facts in order to determine the cost with the acknowledgement of any past car damage and issues.

Very accurate, it measures speed and doesn't care if the vehicle is traveling up or down, toward or away from the radar gun.

The best way to determine the value of a used car is to compare your car to the same make/model/year as another car on Simply look for your car on their website and determine if the price they set seems fair.

Speedometer can determine a car's normal and maximum speed.

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