Radar stands for the word Ring Radio means radio waves ring
Radar electronic system used to detect moving targets or fixed and location. Can determine the direction of radar targets far from the vision of the human eye, as well as determine the distance and height, as it can find the objectives of small insects, or the enormity of the mountains. The radar works efficiently at night, even in dense fog, rain or snow.
Radar and scalability of the implementation of several tasks to make it useful for different purposes and wide; depend on the radar for pilots landing their aircraft safely in crowded airports, as used by navigators in bad weather to drive their ships near the boats and dangerous goals. And uses a lot of countries of the radar guard from sudden attacks of the enemy planes and missiles, and can be employed weather radar to track air approaching storms. Scientists use radar to investigate the Earth's atmosphere above, and also use it to study other planets and moons.
The device operates almost all radar-mediated send radio waves toward the target, and receiving waves reflected from it. Indicates the time it takes for the reflected waves to return over the target and how far?, In addition to the direction in which it waves reflected back on the position of the target.
Different radars in size and shape, but they are all essential parts of one; and each transmitter device for the production of radar signals, and an antenna for broadcast abroad, and brings together the same antenna in most types of radar waves back from the target. And strengthens the future reflected waves which are called resonances that can be seen on the screen. Similar to the radar screen picture tube in your TV, but they are often circular rather than rectangular. Show points of light echoes, or imagination of the target viewer.
History of radar
In 1904 invented the German scientist Christian Holsmier simple device that uses radio beams to prevent ships from hitting each other in the seas, and in 1922 appeared the first system to a long-range radio at the hands of the Italian Guglielmo Marconi the world.
Christian Hulsmeyer
Uses radar
Based air traffic control centers on the radar to track and guide aircraft in flight between airports. Shows radar waves reflected from the planes illuminated points on a circular screen. The flight path can be specified for each aircraft movements follow-up points. In air navigation. Radar is an important tool in navigation. The shares used in all airports and aircraft to a large extent in the safety of navigation.
It is known that the air traffic near large airports are quite dense, so it is used monitors traffic coaches radar at all airports in the world's major to guide the continuous flow of aircraft arriving and departing; it shows the radar monitors the subject of each aircraft in the air in a minimum of 80 km from the airport. And enable this information to prevent collisions by choosing the most appropriate paths to be followed by pilots. Observers also depends on the radar for them to guide the landing ground when bad weather, when a vision becomes the pilots of the lights and they approached the stands during difficult.
And defines a system called secondary radar, the aircraft on the screens of observers in the air traffic. Vtbos wireless signal transmitter on the plane, sends signal cryptographic due, containing the aircraft call sign. And this reference painted on the screen next to the point that represents the plane.
And most modern aircraft of different types of radars to help the pilot. For example, a radar altimeter shows the amount of altitude in the aircraft in flight, and so helps to keep the pilots at a convenient height. There is another way, is the weather radar that detects nearby storms, so pilots can change the tracks to avoid bad weather as they could.
In maritime navigation. Radar is used widely as an assistant for navigation in many types of boats and ships, from cruise vehicle, small to large oil tankers. A radar ship in bad weather conditions to locate other ships, rocks and snowy mountains at the appropriate times to avoid accidents. The navigator can, when the ship near the shore, to locate the ship's radar echoes of the mediation of private floating reflectors, or islands, or signs of other land.
Is used for port officials to control the radar ships in the busy port. They track the movement of all ships in the harbor on the radar screen that gives a kind of image map of the port. And mediated by the Radiocommunication these officials can guide the ships entering and leaving the harbor safely in any weather conditions.
Stations can also track the effects of Coast Guard vessels from the radar observations, and the Coast Guard used radar to search for the ships of the Code and reported as lost.
In the armed forces. Radar uses a wide variety in the armed forces, including the following main applications:
1 - Air Defense
2 - missile defense
3 - space surveillance
4 - poll
5 - measuring range
6 - control arms fire.
Space surveillance radars include the use of superior ability to detect and track satellites, as well as any other targets placed in orbit around the Earth. For this purpose, to invest the United States and Canada called the network system of detection and prosecution space. The system includes three facilities for a missile defense system, and eight other facilities in different locations of the world. He believes this system about 20,000 daily monitoring of hundreds of tropical goals (which revolves around the earth). And help the data received from these observations to identify the satellites used for reconnaissance spy.
Mapping radar contact can be made from an aircraft, this radar map of the city of Flagstaff in Arizona, USA, (right), taken from the height of 12.000 m and show pictures of the city Kaancod yellow. The shape of the land mass to the left of the city is Mount Elden.
Poll - the compilation of information. Radar is used to collect information on the preparations being taken by other countries for the war. Can radar mapping mobile in the plane to produce detailed maps of the Earth, and shows of military installations and equipment. And can other types of radars to obtain important information on missile systems to another country to monitor its missiles during tests at all.
Measurement range. Often used to check the radar range to ensure the performance of military equipment. For example, radar can measure the extent to accurately track the missile flight again. If this is not the performance of the rocket as expected, it can be to trace data that helps the designer to determine the error.
To control traffic speed and flow. Police use radar in some countries to apply the laws of speed and make sure the speed of vehicles on streets and highways. The police radar devices can detect moving vehicles accelerated from about 370 m. And radar signals transmitted from the antenna outside the vehicle the police compound.
How does the radar
How does the radar pulse
Different groups in radar design and purpose, but they all work on the same general principles. And produces all radar and broadcast signals in the form of electromagnetic waves. The radar waves can be radio waves or light waves. And most groups of the radar transmitted radio waves, but few of them are called optical radar or laser radar waves transmitted light.
When you send a group of radio-wave radar waves hit this goal is reflected, and returns a section of the reflected waves to the radar set on the track himself, who sent it. This is similar to reflection, to a large extent, what happens when a person screaming in the mountain valley, heard his cry echoed from the rocks nearby. In this case the reflected sound waves instead of radio waves or light.
The radar waves sent by a specific frequency. The frequency is measured in such a wave is called the unity of MHz. Equal to unity Almijahrtz million hertz (cycle per second). For the waves of radio frequencies for low-frequency light waves, and most of the radars that broadcast on the radio waves operating at frequencies between 1,000 MHz and 50,000 MHz. And optical radars operate at frequencies much higher, and some wavelengths of light are born with frequencies up to a billion MHz.
The groups are designed radars, in many cases, for different purposes and operate at different frequencies. The radars are operating at low frequencies is more effective than those operating at high frequencies to penetrate clouds, fog and rain, so widely used in aircraft and ships. On the other hand gives the radar high frequency, accurate measurements and smaller antennas than those used in low-frequency radars. Optical radar, for example, produce a signal with a very narrow beam from a laser with a diameter of only 1.3 cm. Optical and radar are particularly useful in difficult terrain survey, where you must measure the distant points through the gaps between things big rocks and trees.
The groups vary in how well the radar signals, and are classified on this basis to the two general types, namely:
A radar pulse is the most common
Broadcast signals in the form of intermittent bursts of strong, or impulses, and will continue to wave radar pulses a few millionths of a second. And a set pulse radar antenna and the one used to send pulses alternately and receive repercussions.
Can find the distance to one of the objectives measured the time it takes the wave radar to reach this goal and back. The radar waves travel like the rest of electromagnetic waves at light speed 299.792 km / s. So Valmujh radar return after two seconds, which may be made 599.584 km, 299.792 km in any Go to the goal and the same distance in the second leg, turning the pulse radar automatically set the time required to go and return to a distance of (yet) toward the goal.
The broadcast antenna wave pulses in highly directional narrow beam enables a radar to determine the direction of the target. Waves can not reverse unless the target is located in the packet size only. And determines the direction in which waves are reflected from it into the goal. Pulsed Radar can pursue (follow) the goal, sending a continuous pulsed signals, and measure the distance and direction of the target at regular intervals. It uses this type of radar also for mapping radar from an airplane. The map can be produced pulses of radar scans the package on an area-specific, and draw the intensity of echoes from every direction. The echoes appear in the form of an image on the radar screen, and recorded on a film projector. And produces goals, such as buildings, bridges, mountains, pictures of shiny, because it reflects the strong echoes.
2 continuous wave radar
Broadcasts a continuous signal, rather than short bursts, and there are two types of continuous-wave radar, are:
A Doppler radar
2 radar frequency modulation.
Doppler radar has mainly been used for accurate measurements of speed, and works on the principle of the Doppler effect, a change in frequency caused by the movement. Doppler radar sends a continuous wave frequency is fixed, and uses the same antenna in both transmission and reception. When the transmitted wave to hit the oncoming of the radar, the reflected waves with a frequency higher than the frequency sender. And when the target away from the radar set, the counter-wave frequency becomes less, and the more objective was faster in either direction difference was even greater between the frequency of sending and frequency of the reflected wave. By measuring the difference in the frequency Doppler radar sets the target speed observer.
And the police use Doppler radar to detect speeders drivers. The soldiers used to measure the speed of goals to guide arms fire.
Radar frequency modulation signal is also transmitted continuously, but it increased or decreased frequency signal at regular intervals. As a result, the radar frequency modulation, in contrast to Doppler radar, can determine the distance to the goal of a fixed or mobile. At the time it reaches the radar signal to the target and return, the frequency of the sender's goal has changed. The measured frequency difference between resonance frequency and the sender, and converted to a distance of the target, which produces the echo. As the goal was increased beyond the difference between the frequencies.
Can be used radar frequency modulation, such as radar pulse, in the mapping, and in the prosecution. It can be used on aircraft altimeter.
Sections of the radar range
Varies depending on the size of a radar use; The group of radar used by police to detect speeding cars nearby, can be carried by hand, and weighs about 18 kg. The huge radar units used to study the planets and other distant targets, include large buildings. Some of these units to antennas with a diameter of 300 m.
In spite of the different groups radar are similar in size in the subdivision, and these sections are:
1 - Oscillator:
Device produces an electrical signal with a capacity of low-frequency constant. Specifies the frequency oscillator frequency radar working group.
2 - included:
In the pulse radar, electronic key, connect the sender and separated quickly. Thus, the sender produces short-wave bursts. At the radar frequency modulation changes the built-in wave sent down. And no Doppler radar is included.
3 - the sender:
Serves as the speakers, it takes the electrical signal with a low capacity, and produces high-power signal. For example, produces pulse radar transmitter, the user in control of air navigation, the ability of signal maximum of up to several million watts.
4 - the key to the transmission and reception:
You can use a single antenna for both transmission and reception. And leads key transmission and reception signals sent to the antenna, and prevents the flow of these signals to the future. And strong signals from the sender that may damage the future if it involves sensitive. After sending a wave of the antenna Aousel key transmission and reception, the antenna to the future. And such a connection can pick up echoes of the future to come.
5 - Antenna:
Large dish antenna rotor is used in the radar stations on the line of distant early warning, and wipe the reflectors that work automatically the sky, for the detection of enemy aircraft. The antenna. Sends radar signals in the form of narrow beam of electromagnetic waves, and combines the reflected echoes. As the most modern radar units have a key to send and receive, they use the same antenna for transmission and reception.
It consists of the common type of horn antennas attached at the top of a large reflector dish is called reflecting. Is called the trumpet-band radar, Verzha in narrow beam reflector. The radar antenna is going, so spread this package on the radar scanner targets in all directions.
The groups used in other types of radar antennas operating at lower frequencies or at frequencies too high. It uses radar, which broadcasts radio waves low-frequency antennas are made of metal tubes, rods or similar external antennas for TV. And are used in optical radar, a markedly different device sends high-frequency waves Kaldu ultraviolet or visible light or infrared. This is similar to the means and the telescope (the telescope) and has a glass lens focuses waves emerging in the package.
6 - the future:
Takes weak resonances mediated by the antenna and accumulated much magnified. And the future is so sensitive that it can easily detect echoes with a capacity of less than one millionth of a watt. And will nominate the future noise and other interference captured from the antenna.
7 - Signal Processor:
Pass the reference of the future, in most radar units, during the signal handler before she went to the screen. The lead signal processor and the different functions in the radars used for different purposes, it is obscure in some types of radar echoes from targets large and fixed, and only allows for the echoes from small targets moving up to the screen. And so can the radar signal processor factor, to see the plane, for example, although the echoes of the plane up at one time with a much stronger echoes coming from Mt. The computer in many modern radar signal processor serves.
8 - the viewer (the screen):
Provides for workers in the information obtained from the radar target. Some groups opposed the radar is simple. Fradarat Doppler phones used by the police, for example, have a scale refers to the speed a vehicle or truck, but most of the groups opposed the radar complex, consisting of a tube cathode rays, a vacuum tube fluorescent provider Viewer is similar to the TV. See: vacuum tube. The viewer can display cathode ray tube of radar data in many forms.
And the viewer is the most common index position opposed surface, and gives us a similar map of the area scanned radar beam. And agrees center of the image position of the radar set. And the area around the viewer is included, such as the compass in order to read the direction. And can be opposed to the circles spread from the center of the image to the surroundings to show the distance in miles or km. Show radar echoes in the form of bright spots. And gives the position of the point scale for the compass direction of the target. Shows distance from the center point of the screen after the target amount. It can determine the speed of the target by observing the time it takes to go a point a certain distance Viewer radar.
Show symptoms of other forms of high goal, and uses this type of radar beams in groups designed to help guide the aircraft during landing.
9 - Timer:
Believe play a radar efficiently and easily. And reached this Alnbith main parts to a radar accurately and separated in time automatically, and the timer is doing this by sending control signals to the various sections of the appropriate sequence.
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