1. STEREOPHONIC SOUND,FLAT PANEL TV RECEIVERS AND 3D TV BY, Fisal Shaikh(140753111007) Submitted to, Prof. Jigar Shah

2. Stereo sound systems The characteristics of hearing with two ears that enable perception of both direction and depth of sound besides its loudness. Two-channel recordings, in which sound is played on speakers on either side of the listener, are often referred to as stereo. It is necessary to have two completely separate channels at the transmitter and receiver. Stereophonic effect can be obtained by placing two mic infront of the stage, one taking the place of left ear and the other of the right ear. Such an effect arises due to the difference in length of sound-path lines and hence time delay with respect to each other in striking the diaphragms of two mics. The sound pattern picked up by the left mic is fed to its own recording and reproduction channel. Similarly for left mic.. Only one FM transmitter is used to broadcast both the left and right channel audio signal.

5. The two channel signals are combined in a predetermined manner in the multiplex transmitter before transmition.the signal (L+R) IS obtained by combining directly the left and right signals while the (L-R) signal is obtained on frequency translation as shown in fig. The FM station transmits an (L+R) component and a specially coded (L-R) component.and a plus a pilot carrier to synchronize detection in the receiver. The multiplex receiver designed to separate the (L+R) and (L-R) component in their original form. To obtain the left channel, the two components are added together (L+R)+(L-R)=2L. similarly for right channel (L+R)-(L-R)=2R. For steareo sound transmission in TV the basic principle remains the same. But the left and right signals are accommodatedin a different way as devised ny PHILIPS of germany.in this the IF spectrum consists of vision carrier, a first sound IF carrier at 5.5Mhzand a second IF carrier at 5.7421875Mhzfrom the vision carrier.

6. Projection television Normal TV has max 40’’ inch of screen. Some time we need larger screen where large no. of viewers. At that time projection TV is used. The simplest projection TV system is one in which the picture obtained on the screen of a picture tube is enlarged by a lens system and projected on a large screen.screen unit are attached to the receiver chassis thus making a compact reciver cum projection unit. The brightness of the enlarged image is low and it becomes necessary to darken the room while viewing any programme. An improved version of projection tv which produce much brighter image employs three special picture tubes(RGB). Distance keeping between picture tube and screen is 2.5 meter.it is two piece unit.choromatic aberration is produced when the projector is moved with respect to screen.keep projectors position fixed for optimum image reproduction.while this projector is suitable for commericial application where space is not major criteria. It is not suitable for home viewing.

7. Matsushita Electric Co. of japanpriduced a complete and compact projection TV system having the all the qualities which a home viewer would ask for.it is one piece system.handling ease of a single tube projector brightness of three tube type.the screen size in nearly 150cm square. Sutable for both home and commercial. Projection tv has grow over the years. Recent innovation is reflective technology have brought in MEMS which employ DMD,GLV and LCOS.

8. FLAT PANEL DISPLAY TV RECEIVERS. Picture tube replace by a flat panel display. It make the receiver much compact. flatpannel led to the development of LCD and Active matrix displays.since size and shape of receiver much compact.there are two type of display LCD and Active Matrix Displays. LCD Display LCD is based on the simple dot matrix approach.earlier there were some limitation on the quality of such displays more so for rapidly moving pictures but of late lot of refinement has taken place for their use in pocket TV receivers.Casio computer Co. Japan marketed a 2.6” TV receiver with colour LCD display screen earler and leter a 12” flat screen version. Active Matrix Display Some companies of japan have made considerable advancement towards the development of active matrix flat screen displays. Matsushita electric produced initially a colour display with 10” diagonal and 99 mm thick measurements. The technology employed is known as matrix drive and deflection. It is infact an array of 3000 very small electron tubes with an effective resolution of 270 scanning lines.

10. The display panel measures 370*355*99 mm. it is made up of lattice electrodes approximately 0.1 mm thick layered between insulating boards. As a shown in fig each panel has 15 very fine wire cathods and 200 electron beam control electrodes set 200 across and 150 high, deflected in six stages. The output in micro- processor controlled for uniformity over the surface. With the interlace included, the deflection stages total is 32, with o/p of 192000 picture elements in a 4008480 pixel matrix. Large TV screens based on LCD and PLASMA technology are now replacing the conventional CRT screen.In LCD screen consist of a liquid crystal solution put in between two glass plats. This on application of electric current acts like a shtter to allow more or less light to pass through depending on the intensity of applied charge that is proportional to the applied signal. This forms the basics of picture formation in the screen.

11. Three dimensional television The two-dimensional pictures as we see on the television receiver receiver screen look flat because these lack depth. We human being are able to see in three dimensions since our eyes see a slightly different image of the same scene.the cameras are located suitably like the eyes of the human observer. In practice there can be many such pairs of cameras to shoot from different angles as is the common practice in conventional telecastion.the left and right channel signals thus formed together with sync pulses are amplitude modulate with the station channel carrier in separate modulators.from the output of right channel modulator the upper side band is selected while from the left channel modulator the lower side band is filtered out.these on combing appear as shown in fig.

13. 3D PICTURE DISPLAY TECHNIQUES The techniques used in earlier 3D TV receivers for display of picture on TV CRT screen were based on the use of two video signals in different ways to create the illusion of 3Dpicture when viewed with special glasses. Anaglyphic 3D: in this method that was developed earlier, all the phosphor stripes of green colour of the picture tube are excited by the “G” video signal that originated at one of the two cameras.a viewer wering green filter glass for the right eye and red filter glass for the left eye. Polarization 3D: 3D picture can be seen in natural colours employs two video display units.one unit is fed by the right channel RGB video signals and the other by the left channel primary colour signals.a polarizing film is fitted infront of each video display unit and the two light outputs thus obtained are reflected together through a mirror arrangement on a screen.

14. ABDY 3D : system appeared more promising was developed in west germany and in this system the video signal containing red information is delayed by nearly 600ns by additional circuitary in the signal path. The result is a double image formed on the screen of picture tube which viewed through special glasses make it possible for the viewer to perceive the third dimension of depth.

15. Thank you