Great Advance in Television Tests

Poverty Bay Herald, Volume LV, Issue 17502, 26 February 1931, Page 10

Great Advance in Television Tests

CECKET researches in tJio application j ~f television to entertainment have* I ■ Iji'-iiii carried mil lor some tinfi' in the iaboiatoru's of tlio ( Iramophono | (“JI.M.V.”) Co., at Hayes, Middlesex, j England, and demonstrations of the insults were given recently at the f'hysi- ! cal and Optical Society’s exhibition, [ South Kensington. |j These demonstrations show that telej vision is fast becoming a practical (entertainment proposition. What now remains to he accomplished is chiefly a matter of increased power, technical relinement, and tlio co-operation of the broadcasting authority. The system invented by the Gramophone Co.’s engineers is not associated in any way with the Bail’d system, nor with tho demonstration given in J America by Dr. Alexanderson, of the ! Radio Corporation, with which the Gramophone Co. is affiliated. It is. in essence, an original system, as British as its inventors, chief among whom are Mr. 'Whitehouse and Mr. Browne. It marks a considerable technical advance on any system yet demonstrated, especially in the direction lof bringing television vapidly into use for entertainment purposes, j Even such small details as a piece of | wire netting and the number on a tram car are plainly visrible. i How it is Done

j It would bo useless to describe the technical aspects of (ho invention in detail, because few people .would be wiser for it, but. here, in non-technieal language, is a brief summary of the prol cess:

; The films are passed through an j ordinary > standard-sized film projector, j This is vonnocted with a selective np- ' puratus that dissects each picture into |is component elements of light and shade, a process known as “scanning.’ I The reader will get. an idea of the number of light elements that may he in a picture if lie will examine, by means of a magnifying glass, tlio number of dots that go to make up a ! photograph as reproduced in a uews--1 paper (there are over 2000 dots to the j square, inch in every photograph in some papers). The more dots there are. the more definition •there is in the result.

Each, light element, as it leaves the scanning device, is transformed into an cicatrical impulse, carried over wires, and re-transformed as a light element oil the screen in a position corresponding exactly to its place iit the. original picture l . The dclinilion of the picture mi the screen depends, of course, on the number of light elements that can be transmitted per second. In the case of a, tilin' the transmission must bo fast enough to enable pictures to be formed mi tiie screen at the rate of not. less than per second, the speed actually attained in the “H.M.V.” television demonstrations. Below this speed the pictures flicker, and the intermittenees of the scanning device obstruct the view. The average speed of ordinary film projection is 16 pictures to the second.

200,000 Elements per Second Definition begins at a transmission speed of 120,000 light elements to the. '•second, and full definition will probably •be reached at 300,000 to the second. The transmission speed attained in the ‘•11.M.V.” demonstrations is something under 200,000 light elements per second. These demonstrations, therefore, show Unit the optical illusion called •‘persistence of vision,” oil which the entire cinema entertainment is based, can ho obtained by televised film, pictures, and that definition equal. to ordinary film projection will follow in duo time. It will come very soon if the process can enjoy the full facilities of short-wave broadcasting instead- of land wires. \

The Gramophone iCo.’.s system, is not confined to the transmission oftfilms, though films were cleanly born to he tclovised. Any image, moving or otherwise, that can he formed in , a translucent reflector, -such as a ground-glass screen, similar to tho view-finder of a camera, can he televised by this process as films can bo televised. It is mainly a question of cost and distribution.

It. would bo possible to refleejt an image of the winning-post at- Kpsuin and transmit tlio finish of the Derby, but it would be more convenient to film the •iinisli and transmit lbe film to all who had receiving sets within the effective radisu —a question of power and facilities. Stageplays could he transmitted while in prograss from rebeclors set up jp the theatre. Questions of color and sound-syn-chronisation still remain to be settled, but they do nut present insuperable difficulties.