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1945 Theatre Catalog, 4th Edition, Page 587 (559)

1945 Theatre Catalog, 4th Edition
1945 Theatre Catalog
1945 Theatre Catalog, 4th Edition, Page 587
Page 587

1945 Theatre Catalog, 4th Edition, Page 587

' point to be watched in this connection is that high-tension cables should be as short and direct as possible and without pronounced bends, to avoid the production of brush discharges.

Program Distribution

Very little work has been done so far in the setting up of a network for the particular purpose of distributing television to cinemas. Normally, the programs haVe been taken from an established radio transmission, and for this purpose directional aerials have been erected on the roofs of cinemas which feed the radio energy down to the radio receiver in the projector. In the future, two methods of distribution will have to be worked out in parallel. .One method is by coaxial cable, which has so far proved to be very expensive, and which, in terms of present technique, has set a limit on the amount of detail which can be carried, but helpful results have been obtained over short distances by the use of standard telephone cable with repeater stations at frequent intervals to correct for the losses incurred. It is quite possible that, in due course, standard telephone connections will be satisfactory for working from one point to another inside a particular city, but, for transmission from one city to another, the cable method is bound to be very expensive. It has the advantage, however, of maintaining secrecy and reducing interference compared with the second method, which is by radio relay. (Figure 12.) DeVelopments during the war on ultra shortwaves indicate that the point-to-point radio transmission of high-definition television signals will be a practical possibility, and the technician who wishes to deveIOp a network of nation-Wide distribution will undoubtedly study each method and make use of either cable or radio in accordance with circumstances. One of the disadvantages of the radio method is that the ether is subject to many forms of interference which are not yet under control. Diathermy installations, high-power highfrequency heating equipment in factories, motorcar interference, and many other types all need to be watched as being factors liable to ruin the reproduction of a television picture. For instance, close by one of the theatre installations in London was a medical establishment where diathermy equipment was in constant use. The only way to insure a satisfactory demonstration free from interference was to ask all the members of the medical institution to attend the performance so that their equipment remained silent. No doubt, many of these forms of interference can be eliminated by local screening and other methods which may have to be enforced by legisIation.

Costs and Charges

It is difiicult to estimate at this early stage of the art what the exhibitor will have to pay to have a complete television large-screen equipment. Before the war, the cost of a projector for providing pictures 15 x 12 feet, which would satisfy the public on the occasion of special events and including the cost of







FIGURE lO.-Here is a diagram of the light-valve (storage) proiedlon system. In this equipment a thin film of liquid is subiect to the action of a cathode-ray beam, which deforms its surface in such a manner that the point-by-poinf density is changed in accordance with the picture pattern scanned on its surface. An exterior arc lamp proiects through this film and a lens on to the Iheaire screen. The proiector (see Figure 9) appears expensive.

spare tubes for replacement, was approximately f2,500 ($10,000). This figure, however, cannot be taken as a basis for commercial installation. The figure may be higher or it may be lower, and it is

duction price of equipment can be established, and then the exhibitor will have to know What service he is going to get with it, before he will be able to decide how far the exploitation of television


will benefit him. In due course, naturally as the situation develops both technically and commercially, he Will find that he will have to install television to satisfy his public.

impossible at this stage to give an exhibitor a basis which will enable him to calculate whether such a capital outlay would be justified in box-oiiice results. Several years must pass before the pro FIGURE ll.-Here is a diagram of a complete 1hearre television System, comprising pick-up, control, distribution, and theatre reproduction. Such a system would be capable of dealing with events taking place in one urban area (such as London) and distributed not only lo theatres in that city bu! also to theatres in the provinces. Note that the pickup points include motion-picture studios, stage theatres and music halls, and the centers for sports.

LONDON FiI-m West End Wembleg Lord's Harrinqag Albert Mobile PROGRAMME Shjdios Theatres Stadium Ground Arena (Paggalits Units i (Sta e) (F0 lb III (Ci k t) (B ' ) u i I D b , SOURCES 9 0 a "C 8 m9 " 5 c) [Boaingca] Ca bIe Wimbledon able TennIs Cable Cable cable Cable F-m- mmmmj RadioLink [ - STUDIO I FILMS FOR INTERVIEWS I DISTRIBUTION I l CENTRE I I (LONDON) I CONTROL ' L a . a - - a - - - -I Cable LONDON Provincial THEATRES Epdkio ProgrammeSources In 5



Birmingham Manchester Glasgowefc.

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1945 Theatre Catalog, 4th Edition, Page 587