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How to send and receive television pictures? | Audio Video
How to send and receive television pictures? In order to understand how to send and receive images, we must go back in time and look at a very outdated technology: cathode ray tube television
In order to understand how to send and receive images, we must go back in time and look at a very outdated technology: cathode ray tube television. Without giving too much in physics, the tube is a piece of glass with no air. Inside the tube is a cathode that emits electrons when it warms up - this is why we need a little time to have your picture appears on television, because the cathode must first be heated to an appropriate temperature to emit electrons -.
There also is a strong electromagnetic field that accelerates electrons toward the front of the tube, and is used to position the electron beam - a lot of electrons is sent to the front of the tube -. front of the tube is a phosphor-coated, and when the electrons hit light will be emitted on the other side - the side on which you sit and look at the screen -. Television means remote viewing. It is a way of sending pictures of the event at a time when they occur - live broadcast - or broadcast movies from tape or tape recorder. Simultaneously with transmitting pictures by radio and the sound is sent.
First of all, images are sent through the air. Transfer is actually electrical impulses. This means that the image should be converted into electrical impulses at one end, that would be turned back into the picture at the other end. look, in outline, how this is achieved. lens camera transmits the image on the glass plate sensitive to light. This panel ejects electrons. With the bright area of the image throws a lot of electrons, with small dark . These electrons are then collected on a separate plate.
On the other side of the plate in which electrons are collected in a tube camera, there are elements that send electrons in a thin stream to the board. This jet moves left to right, descending when this is so that the cross across the board in line 625 and is repeated 25 times per second. jet that returned from the board was changed - modulated - with regard to refuse if it is light or dark surfaces. return jet is sometimes strong, sometimes weak, depending on the image to the board.
This return stream of varying strength is actually a group of electrical impulses, which goes to the amplifier, and thereafter at the antenna from the TV stations that broadcast. At the other end, on which is done before and captures pulses home TV antenna, and sends them to the TV amplifiers, and hence the source of electrons is placed in your TV tube. This source emits a jet of electrons falling on the TV screen. This jet moves in the same way as a stream of electrons in a tube camera, converting the image into 625 lines 25 times per second. The screen is coated with phosphor, which emits light when it comes to the electron beam to finally get the one with the picture that was sent to the air from the camera.
amount of electrons in the jet pipe in the television receiver shall be amended in the same manner as in the modulated stream of camera tubes, making the screen bright and dark areas in those same areas as seen by the camera