Radio age research, manufacturing, communications, broadcasting, television (1941)

RADIOPHOTO STANDARDS Uniformity in Machines and Methods of Transmission Would Insure Success in International Exchange of Pictures by Radio. By S. H. Simpson, Jr., and R. E. Hammond Program Transmission Service RCA Coinmunicatioiis, Inc. STANDARDIZATION seems to be necessary in our modern life. Imagine, for instance, how- much nicer a Sunday on the high- way would be if automobile bump- ers were all the same height; and whoever thought so much argument would arise about fixing the length of women's skirts fourteen inches above the ground! In present day Radiophoto operations, too, stand- ardization is a major objective. Prior to World War II, RCA op- erated direct Radiophoto circuits between New York and London, Berlin, Moscow, and Buenos Aires, and from San Francisco to Tokyo. These circuits operated on stand- ards recommended by the Cairo Conference in 1935. During the war many additional direct Radiophoto circuits were es- tablished by commercial companies, foreign administrations and govern- ments, by the U. S. Army, Navy, and the Office of War Information. PHOTOGRAPHS SENT BY THE EARLIER RADIOPHOTO SYSTEMS USED THE "VARI- ABLE dot" METHOD OF TRANSMISSION, RESULTING IN THE HALF-TONE EFFECT SHOWN BELOW. Wartime urgency and production difficulties forestalled progress in standardization and consequently, many types of Radiophoto machines were pressed into use. These machines performed well on their own networks but not when teamed with each other. Therefore after the war, when these circuits were taken over by commercial com- panies, they found it necessary to opei-ate with four or five types of machines in order to cooperate with points throughout the world. Fundamentals of Radiophoto To operate a worldwide Radio- photo service on an economical and efficient basis, all transmitting and receiving centers must conform to the most desirable standard of op- eration. With the ever increasing tempo of today's business there is a serious need for adherence to standard methods which permit faster exchange of Radiophotos and which will enable the wire networks of Europe to be tied in directly with those of the United States. Before the problem of standard- ization in Radiophoto communica- tions can be understood, it is help- ful first to understand something about the fundamentals of picture transmission and also about radio circuits. Basically, all picture transmission systems operate by breaking down the copy, which is to be transmitted, into small areas for transmission and then, after reception, building up these small areas to form an image of the original. In Radio- photo this is accomplished by me- chanical means; in television, which is considerably faster, the process is performed electronically. In Radiophoto the mechanism consists of a revolving cylinder and a scanner or recorder which tra- verses on a lead screw across the cylinder, like the tool holder on a lathe. In this manner the subject is scanned in a continuous spiral and the photoelectric cell in the scanner changes the light reflected from the subject into correspond- ing electrical currents. At the re- ceiving end the same arrangement is used but the scanner is replaced by a pin-point of light which, as it is varied in brightness, exposes a photographic film or paper fastened on the rotating cylinder. One of the TODAY'S IMPROVED RCA RADIOFOTO SYSTEM PRODUCES THE MUCH FINER DE- TAILS AND GREATLY IMPROVED CONTRAST EVIDENT IN THIS ILLUSTRATION. [14 RADIO AGE]