0
The "radar gun" is not the same as position-finding radar. Using microwaves (or a pulsed laser), it determines the speed of an object by measuring the change in the frequency of the waves when they are reflected back toward the gun.
In this application it is useful to think of light as a series of waves. Radar then is radio frequency waves sent out from the radar gun to the vehicle under consideration. These waves travel at a set speed that is constant, nothing can change how fast they go, but the distance the waves are from each other can be varied. This spacing of the radio waves is referred to as the frequency.
The closer the waves are to each other, then more of them can travel past a certain point in a given second. The farther apart the waves are, the number passing a certain point in any given second will be lower. Frequency then is a measurement of number of waves per second passing a certain point. Usually we don't consider unit-less values in such measurements so frequency is just considered to be (/second), (per second), or Hertz.
When a radio wave strikes a car it is reflected back the way it came, back to the radar gun where there is a coil that can detect them. If the radar gun were fired at a stationary wall the frequency of the waves coming back would be exactly the same as the frequency of the waves going out, and the instrumentation of the gun would interpret this as a stationary object.
If the wall was moving towards the gun however, then, in the time between the successive radio waves striking the wall, the wall moved a little bit closer to the gun. This makes the second radio wave get reflected sooner and the second wave travels back to the gun closer to the first wave then when the two of them left the gun. This is an increase in frequency. The radio waves are still traveling at the same speed (the speed is always constant, can't vary) but they are closer to each other, more concentrated.
The instrumentation in the radar gun detects this change in frequency and uses it to calculate the speed of the approaching wall. It works the same way to determine the speed of a car.
Wiki User
∙ 14y ago
Add your answer:
Earn +20 pts
What is radar cruise control?
basic cruise control but the speed maintained is controlled by radar sensors. the car decelerates when a slower vehicle pulls in front and the accelerates when the road is clear. ANSWER: above is not quite right it does provide a safety margin of distance from an object. I will accelerate but only to the previous set speed.
What is the advantage and disadvantage of radar range over radar bearing?
There is no "advantage and disadvantage of radar range over radar bearing" because they're two separate measurements. You take both measurements with a radar. Your first measurement listed was radar range. It's pretty simple to measure. Your radar puts out a pulse of energy. That energy flies through free air at 300,000 kilometers per second--it's a little less but that number will work. It has to hit the target and come back, so the speed of radar is actually 150,000 km/sec. If the pulse comes back 1/10,000 of a second after it went out, the target is 15 km away. Radar bearing is even simpler: you index your antenna to true north. If your antenna is turning and it gets a reflection when your antenna is on a 40-degree azimuth, and the target is 10 km from where you are, you can pinpoint the guy pretty easily. There are a few other tests you can do with a radar, like altitude (this is done with a radar that scans up and down rather than side to side, used in conjunction with a distance-measuring radar - if you know the angle from you to the plane you're trying to shoot down and its distance from you, you can calculate its altitude) and speed. Measuring speed is done with a radar with a fixed antenna, and it uses the Doppler principle. You send out a radar beam at a known frequency. It reflects off the target, changing frequency as it does - the frequency increases if the target is moving toward the radar, and decreases if the target is moving away from it. (This is how police radar works, and a million cops can't be wrong.) When the beam returns to the radar, they mix the returned signal with the signal coming off the oscillator. They will "beat" together and produce a signal with the difference frequency - if you send out a 10 GHz signal and get one back that is 1200 Hertz lower, mixing the two signals out-of-phase produces a 1200 Hertz signal. They know the number of Hertz the signal will shift for each mile or kilometer per hour; divide the difference signal by the difference-per-unit of speed, subtract the legal speed in the area, and you get the amount of trouble you're in. You can also guide missiles with radar. This takes two radars. One of them is a target tracking radar. The other is on a different frequency and its antenna is steered by the target tracker so it illuminates the thing you're trying to kill. The missile senses that second radar's frequency and rides in on the radar beam. And finally is the Phased Array Radar. Phased array radars consist of a panel containing thousands of radar transceivers arranged in a grid, that are switched and interpreted by a computer. You can install multiple panels in your system; the AEGIS radar system the US Navy uses has four panels in it. The advantage of a phased array is it can do everything all the other radar types can do, at the same time and on multiple targets. The disadvantages are that it's expensive, it's big and it requires a huge amount of power to make this work - the AEGIS system has a maximum power output off all four arrays of 6 megawatts. (This also introduces a workplace safety issue; an antenna emitting 1.5 megawatts of microwave energy will cook - literally cook, just like a microwave oven - anything within ten feet of it. Crewmen on AEGIS warships have to pick up the dead seagulls off the deck after the radar is used; if a bird flies in front of one of those arrays, it gets killed.) The advantages - being able to track altitude, speed and direction on every plane in the sky, and guide missiles on the hostiles, all at the same time on the same screen - so outweigh the disadvantages that designers will use phased arrays any time they can.
What was titanic top speed?
Its top speed was 21 knots, so they could determine the exact time it would arrive at its destination.
In outer space the astronauts can turn the rocket engine off and still continue to travel at their current speedhow is that pssible?
On Earth, this would be impossible because of friction. Moving objects hit air particles and start to slow down. In space however, there is no air. It is a complete vacuum. So, free from friction, moving objects keep their speed.
What was the minimum speed in the movie speed?
The bus must be kept moving above 50 miles per hour (80 km/h) or the bomb will explode.
What are the uses of speed gun?
Not actually a gun, it is a hand held radar unit that can measure the speed of moving objects, such as cars, baseballs, etc.
What is raddar?
Radar is an object-detection system that uses radio waves to determine the range, altitude, direction, or speed of objects
What does the radar show?
speed of movement of the objects detected.
What is the palindrome for-instrument-used-to-determine-speed?
radar
What is the palindrome for an instrument used to determine speed?
Radar.
Which radar is used to measure the speed of vehicles?
A radar gun measures speed of a moving object basically cops use them
What does the Doppler radar show?
speed of movement of the objects detected.
What does Doppler radar shows?
speed of movement of the objects detected.
When was RADAR first used to clock pitching speed?
RADAR was first used to clock pitching speed in 1972. Earl Weaver was the first person to use the RADAR gun to determine speed in baseball.
What do you need to know other then speed to determine an objects velocity?
The direction in which it's moving. This is a very important concept, and a great question.
What is blind speed problem in radar?
The speed at which he moving target cannot be detected means uncancelled clutter interference with moving target takes place is called as blind speed. It occurs in MTI radar-----------------afsha(TE EXTC)
Air craft detecting device?
Radar is an object-detection system that uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircrafts.
