TELEVISION SYSTEM

Radio Record, Volume I, Issue 43, 11 May 1928, Page 2

TELEVISION SYSTEM

A SIMPLE EXPLANATION, Few scientific secrets have been more carefully. guarded in the last decade’ than those relating to the methods adopted in the television systems now undergoing trial. It is evident from the brief reports received from time to time that the problem of television has at last been solved. The success recentlv reported was one of the most striking yet achieved. A liner in mid-At-fantic, fitted with a television receiving

station, was able to "pick up" pictures broadcast fron: Great Britain, with such clearness at times those those on board declared that the images of friends ashore were practically faultless. Sixteen Pictures a Second. _ Efforts to develop a system of television have been made from time to time practically ever since the imyention of the telephone. From the beginning, the gencral principle to be adopted was clearly understood. The dificultv experienced lay in the construction of apparatus to apnly the principle. For the production of an effective

"moving" picture, about 16 successive "fixed"? pictures mst be produced, one after the other every second. If fewer pictures are produced, they do not blend together well, and the resulting moving picture is inclined to be jumpy. For the electrical transmission of a picture, the original must be analysed into a series of very smeli sections, which for effective transmission cannot be Jarger than small lots, such as make up the illustrations in "The Rad‘o Record."? Fach one of these points must he transmitted scparetely from the sending to the recciving Instrument, : and at the receiver cach seetion or dat must be placed in its correet position on the reeeiving sereen. The actual transmission of the dot in its correct tone of light presents no diffienlty. This can readily be accomplished by a photo. electric cell at the transmitter, which controls the intensity of Hieht from a special ‘ies: sat to se Sree Jhe real ditlieulty of television lies in analysing the picture into many thousands of sections so quickly that the process takes place at least 16 times a second, and then rebuilding it, equally rapidly, at the receiver. The generat method adopted by modern workers) consists of the use of a series of rapidly. revolvipg prisins. These prisms are: placed between the image and the, photo. electric cell, and as they revolve! they "sweep" the image in such a way that one sectjon after another of it is. focused on the photo. electric cell. At the receiver the proccss is reversed. ; The light from the lamp is passed on te. the series of revolving prisms, which, bend it out of its ordinary straight line, ' and scatter it over a ground glass re-! eciving plate, so that the point of light! from the lamp falls on every section of. the surface of the plate 16 times a: second in the correct intensity to build up an image. A GLASS FRONT PANEL NAV UR AT ADA NOPNGIS There are a number of advantages to be obtained through the use of glass for panet and eabinet material ‘The principal one is, of course, that glass is transparent and will allow the appatus aud the wiring to he seen frem four sides without ter the Hd af the cabinet. A direct advantage of this lies in the fact that such a cabinet will he more or Jess dust and trouble proof. When the lid of a cabinet is allowed to remain un for anv leneth of time to observe the operation of the valves, or the functioning of the other parts, dust ig sure to scitle on the condenser vlates and other parts of the set Mhris will seon give your set a sheap-worn Moapcarance and reduer dhe eeiongy of ite operation. Té vou are a careful workman and tale pride in a good, neat job of wiring, a e@lass panel and cabinet will anveal for the reason that your workmManehin wel) slewaes he in olay view Glass a Good Insulator. Last but not least, lacs is one of the

best insulators available, and is especi- | ally vatuable in the construction of | radio equipment due to its low electri- ’ cal losses. Glass does not absorl mois- | ture or have the bad capacity effects | that are inherent with some wood cahi- | | nets and panel materials With the preper degrze of care, and a: little patience, the task of drilling © holes throuvh a viece of plate-glass is | not at all diffiendt. , Secure a piece of plate-glass ent to the size you wish your panel, There. are two methods avatable for mak-. ine the holes throuel: the glass for the shafts of the instruments of vour set, screw holes, ete. One method is to e1low bvdrefluorie acid to eat a hole throueh the wlass, The other method is to drill a hole through with carherondun: and turnentine as a entting fluid Acid Makes Froles. Spot the gives at the points where you wish to drill a hole. In case you

desire to use the acid method make a small mound of clay over the spot. Make a small epening through the clay with a lead pencil, the exact size you wish to have the hole through the glass. Now pour a smaji quantity of the acid in the clay mould and allow it to stand. The length of time required for the acid to eat through will depend jon the strength of the acid and the |} thickness of the panel. Condenser-shaft holes cuonld be bushed with chonite tubing if desired.