 Hello friends, myself, Ilya Arshanjane, Assistant Professor from Department of Electronics, Valkan Institute of Technology, SolarPool. Today, we are going to see the topic TV Broadcast System from the subject Audio Video Engineering. So basically, what are the learning outcomes from this topic? At the end of this topic, students are able to explain the working principle of TV broadcast system. They can explain the working of TV transmitter system. They can explain the working of TV receiver system. So basically, this is the simplified block diagram for TV broadcasting system. And generally, this is the transmitting side for TV broadcasting system. Here, there are different blocks. As you can see here, there is a television camera, video amplifier, AM modulating amplifier, audio amplifier, FM modulating amplifier, FM sound transmitter, crystal oscillator, RF amplifier and power amplifier, which then gives the output to the combining network, which has the input from video and audio, and then the combining network gives the output to the transmitting antenna. So basically, this is the block diagram for TV transmitting system. So let us now see the explanation for the same. So here, a TV camera is used as we have seen in the block diagram, which converts optical information into electrical signals. The amplitude of which varies in accordance with the variations of brightness. An optical image of the scene to be transmitted is focused by using a lens assembly on a rectangular glass faceplate of the camera tube. The inner side of the camera generally consists of glass faceplate, which is a transparent conductive, which has a transparent conductive coating on which it is laid a very thin layer of photo conductive material. That means whenever the electrical signals which are passing through the camera, they go and bombard on the photo conductive material, which then illuminates. Thus, depending on the light intensity variations in the focused optical image, the conductivity of each element of the photo layer changes accordingly. That means according to the different, according to the light intensity variations, the brightness of the picture or the scene varies. Hence, this is done by using an electronic beam which is used to pick up the picture information. This beam is formed by using an electric gun in the TV camera tube. So, on its way to the inner side, the electrical signals pass through a pair of deflecting coils which are mounted on the glass envelope. Hence, the rays get deflected and these travel in a mutually perpendicular path towards the photo conductive material. So, these deflecting coils are generally used for achieving the scanning purpose. Here, the scanning used in TV broadcasting system is generally an internal scanning and this is done in the same way as one reads a written page. This means whenever we start to read a page, a line on a page, then we start from the left-hand side. We go on towards the right-hand side and as the line ends, we again come to the left-hand side of the next line and then again we start reading the book. So, this is the same process which is used in the scanning. So, this is all about the TV transmitting system. Now, we are going to see the TV receiving system. Here, as you can see, there are different blocks used. RF tuner, common IF amplifier, video detector, scanning and synchronizing circuits, video amplifier, audio amplifier, FM sound modulator and sound IF amplifier. So, this is the receiving antenna, this is the loudspeaker and this is the picture tube. Here, this loudspeaker is generally used for reproduction of the sound. Picture tube is generally used for the reproduction of the video signals. So, basically now we are going to see the working of the TV receiving system. Here, the TV receiving antenna intercepts radiated RF signals and a tuner is used which selects the desired channel frequency band. Here, the antenna which is used, it provides RF picture and sound signals for the RF amplifier stage. That means, the receiving antenna captures the desired RF picture signals and sound signals. The RF stage is then coupled to the mixer stage. Here, the mixer stage is generally connected to the local oscillator. These three combinedly provide a heterodyne receiver and the output of these three blocks is nothing but an intermediate frequency. Here, the RF amplifier, mixer stage and the local oscillator stages generally these three combinedly are known as RF tuners. Which is the basic block at the receiving side of the TV broadcasting system. The output signal from the tuner circuit is amplified by using a common IF amplifier. The video and audio components are separated by using a detector. As we know, these are separated because video signals generally contain the higher signals and the audio contains the less frequency signal. Here, these are needed to be separated. This is done by using a detector. Hence, after separation, the video signals are again demodulated by using a AMD modulator and audio components are demodulated by using a FM demodulator. The sound signals are then detected from the FM waves. These are then amplified and then fed to the loudspeaker which reproduces the sound signal. The video components similarly are first passed through the detector which separates the picture signal from the synchronizing pulses. Generally, a line synchronizing pulses and frame synchronizing pulses are used for the video components. These are then fed to the horizontal and vertical deflector plates of the picture tube for the synchronization between the different pictures. The blanking pulse are generally given to the control grid of the electronic gun of the picture tube. These blanking pulse are generally used for blanking up the retrace period during the scanning process. The picture signals are applied to the filament of the electronic gun of the picture tube. According to the variations of potential in the picture, potential is nothing but the brightness. Electrons are emitted from the electronic gun. Thus, the intensity of the fluorescent screen of the picture tube varies in accordance with the variations in the brightness of the picture and hence the picture gets reproduced. So, this is all about the TV receiving system. These are the references for you people. Satellite communication third edition by Dennis Roddy. Composite Satellite and cable television systems by R. R. Gulati and a research paper which consists of universal digital satellite receiver. It is of IEEE journal. Thank you for watching the video.