Radar and Sonar
Sonar (previously known as ASDIK in the UK) is a system for finding directions and distance using underwater sound waves. Radar is based on the same principle, but uses radio waves instead of sound waves.
Both systems are basically simple Acoustic (sound) or electromagnetic (radio) waves are sent. When these waves diverge to a solid object, some are reflected and come back to create a sound or wave echo. The path taken is found by multiplying the time between the departure and arrival of the wave by multiplying the speed of the wave. Normally this is twice the distance to the object in question. The first radars made during the Second World War would be loaded onto the trailer to move. Some had a “lens” for directing the radar beam.
Development and Uses;
Sonar means sound maritime science and distance determination (consisting of the first letters of English soud Navigation And Ranging) and was developed primarily to detect submarines, other ships, mine terraces, glaciers, sunken ships and other underwater hazards. Sonar can be “active or” passive. ” An acoustic wave is sent in the active sonar and the echo is recorded. In the passive sonar, the ships are detected by the sounds of their machines. Today, sonar seeks fish herds by fishing vessels and uses them to examine the ocean bottoms.
In 1935, a British group led by Robert Wvatson-Watt (1892-1973) started a research program aimed at developing radio navigation tools for military use. When the Second World War broke out (1939), Britain set up an aircraft detection system along the east coast. This system, known as RDF (radio navigation), was soon placed on the southern coast, and was the main factor in the British winning the air war against the British air war despite the low number of aircraft.
The secrets of RDF later moved to the USA. Here, too, intensive research has been done here, and the new technology has been given a new name (radar). In the early years of the war, German scientists also conducted such research. The results obtained in Germany were similar to the radar but technically more backward.
A radar equipment consists of three separate units. A transmitter emitting a special radio wave, a receiver that receives and evaluates each reflected wave; and a display unit, a display where the radio can read the desired information immediately.
Radar Antenna Types:
The forms of radar antennas vary depending on the purpose of use. Most of them consist of a flat metal cage in the form of a square or circle, which can be turned in the desired direction. Some. It can be locked in a certain direction for automatic tracking of a target. The beam of the navigation radar focusing with a parabolic reflector is narrow, just like a projector beam. Thus, the height and scope of the reflected waves can be accurately measured. The surveillance radar has an antenna that transmits waves by drawing a wide arc. In the ship radar, the beam is kept relatively flat. The planes draw a vertical arc. In both cases, sometimes the antenna is rotated so that the radar can constantly scan the environment. In most radar receivers, antennas are usually made to receive as much of the weakly reflected wave as possible.
Evaluation and demonstration
The radar signals that are properly processed and enlarged are sent to the display unit along with the first sent wave.
The signal display system is a cathode ray tube, usually based on the oscilloscope. On this screen it is possible to read the distance or height, or both. On the other hand, the screen can be given a complete electronic “map” specific to the locations of the objects that reflect waves in all directions.
The direction and height of the object (for example an airplane in the sky) detected on a simple straight line display is read on a dial indicating the direction and height of the radar beam, the direction and height of the radar beam. The distance is read from a bright line in a straight line oscilloscope, where the time distance between sending and receiving is twice. The gauge (PP) image is obtained by a straight line oscilloscope screen, arranged in the center of the tube and ending around it, arranged by radial scanning. Then, the scanning pressure sensor is rotated and the scanning is rotated in accordance with the rotation of the antenna. The oscilloscope screen is covered with a long-term phosphorus-based substance. Thus, the reflected signal (a bright spot) on the screen continues to appear until the antenna has completed a lap. The reflected point shows the distance of the tube from the center, the object distance, and its size on the screen matches its actual size.
In some systems, most of the radar equipment is due to weak waves reflected from solid objects, although the relay is the receiver and transmitter to jump and send the reflected wave more strongly. Systems that receive and send the wave are called “secondary radar”.
When an electromagnetic wave is reflected from an object moving away from the radar or approaching it, the frequency of the reflected wave changes. This event, which is very well known in phonetics, is used to measure the frequency shift of the doppler phenomenon, the occurrence of the sea, the velocity of the object.