International projectionist (Jan-Dec 1939)

throughout the whole broadcast circuit, to bJanket the country? Mr. Kaar: That is a difficult question to answer because I am not familiar with the recent progress on coaxial cable. You will find a description of the New YorkPhiladelphia cable in the literature. As I remember, it has repeaters every ten miles and as yet will not transmit the full band required. Perhaps some day transcontinental cables may be laid capable of handling television programs, but I can not say that they will. The other system is satisfactory and has been tried. As to the economic balance between the future use of cables and ether channels, that still remains to be answered. Mr. Goldsmith: The New York-to-Philadelphia cable was said to have cost $540,000. Whether that included large engineering developmental expenses or not, it is not known. In any case, that would have indicated a per-mile cost of $5,000 or $6,000. The major broadcasting networks in the United States today use somewhere on the order of 40,000 or 45,000 miles of lines, and if one multiplies that by $5,000 for the cost of laying a similar coaxial cable network, the result of the multiplication is an extremely large and uneconomic amount. However, it is believed that development will lead ultimately to less costly coaxial cables with repeater stations closer together and satisfactory for the purpose, or to economic radio relay systems that will work very effectively. Mr. Kaar: The fact that such a serious problem exists in chain programs comes pretty close home to the motion picture engineer, because for the immediate present there is an answer to the chain broadcasting of television programs, namely, the transmission of motion picture films, which will undoubtedly be done extensively. Mr. Goldsmith: There are many practical and artistic reasons why film will necessarily be widely used. Mr. Williford: Does the adoption of the 60-cycle frequency as standard mean that communities having 25 or 50-cycle power supply are definitely out of the picture as far as television is concerned? Mr. Kaar: There is no connection between the synchronizing mechanism of television and the power frequency. The synchronizing is accomplished by transmitted signals. The only reason and the advantage of choosing a frame frequency that is a multiple or submultiple of the power-line frequency is this: If a system should develop a ripple, as we know it in audio work, that ripple would occur at power-line frequency. If the frame frequency occurred at some other frequency than that, this ripple, which would be either a light area or a dark area, would travel across the screen. If the system is perfect and there is no ripple, it makes no difference at all. This is simply chosen as a safety measure. Mr. Goldsmith: If the power-supply system of the receiver and its shielding are so engineered that no such effects appear, the receiver can be used equally well regardless of the power supply. Mr. Cable: It seems to me that the frequency chosen as 30 places a definite limitation on the picture brightness, because frequency is a function of brightness. Mr. Goldsmith: The present standard is 60 pictures per second. We see 60 "half pictures," with interlaced scanning. First is shown a picture with lines 1, 3, 7, and so on, as a full picture; and the one with lines 2, 4, 6, 8, and so on, as the next picture, a sixtieth of a second later. So the frame frequency is 30 but the field fre PROJECTION steady, brilliant, snow-white ... 2 to 3 times as much, at less cost per unit. Essential to satisfactory projection of color pictures. Write for catalog on the Strong Mogul and other unconditionally guaranteed products . . . your guide to better projection. Demonstration without obligation. For Sale By Independent Theatre Supply Dealers Everywhere. THE STRONG ELECTHICCOHPOHATION 2501 LAGRANGE STREET • TOLEDO, OHIO Fxport Office Room 2(1112. 2211 W. l >"H St.. Nm Yn-k r:.v How Many? Was this copy dog-eared when it came to you? How many men read it ahead of you? You would receive a clean, fresh copy if you had a personal subscription — and you wouldn' t have to wait — you would be first to read it. Use coupon below. INTERNATIONAL PROJECTIONIST, 580 Fifth Ave., New York, N Y. Enter my subscription for □ 1 D 2 year — 12 years — 24 issues — $2.00 issues — $3.00 . ?oreign: Add 50c per year. City State JANUARY 1939 25