Here Comes Television!
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In a television studio. Left: Directing a scene on a "live" stage. Two cameras are used to introduce variety in the angles of view. Right: Another stage setting showing, in the foreground, the latest type of lighting equipment med in television studio work HERE COMES TELEVISION! Will Serve Entertainment Needs • • • Technical and without a trace of flicker. The trans mission apparatus, although almost in· Equipment Has Limitations Standards Laid finitely complex in design, is entirely re liable. In a recent demonstration at Down to Prevent Obsolescence of Receivers Washington, D. c., in which the NBC mobile television units were the trans By o. B. HAN SON mitting station, not one minute was lost Vice President and Chief Engineer in more than 30 hours on the air through National Broadcasting Company equipment failure. I assume that the com mercial- receivers soon to be marketed OR years people who knew of my will also be reliable and simple in Fconnection with television have been operation. UST prior to the arrival of asking: "When do we get it?" When· J scheduled television programs y description of television's appa ever the temptation to predict grew on the American scene, we pre· M strong within me, I would mentally turn sent the accompanying artide to ratus will naturally veer toward the the pages of old magazines-"Television give a comprehensive view of the technical. And since I am most familiar Comes to the Home" (1928), "Television situation as it stands today. Writ with the NBC equipmeu"t, I shall use it Gets Ready for Business" (1930), and so ten by Mr. Hanson at our reo as an example. Our apparatus embodies (luest, it dears- up many miscon. on-then mutter a few incomprehensible the RCA all·electronic system of tele· ceptions about the subjecl.-The phrases and let it go at that. Now I am vision. In the camera, fitted with a pho Editor. in happier circumstances. Broadcasting tographic lens system, the light image is of regular television programs to the focused on a photo-sensitive mosaic in metropolitan area of New York will start· side the Iconoscope, a highly evacuated in April. The same time has been chosen tation that will be used in other media. tube shaped somewhat like a dipper. The for marketing the first commercial reo Will there be national television net photo image is here registered and its ceivers. Together; the two events mark works? What about the movies and tele light values 'converted to electrical po the real beginning of American tele· vision? Who will appear on the television tentials. We have here a "picture in volt vision. screen and what will the programs be ages," which, to be useful, must be an It is probable that the average intel like? And what is television and how alyzed, taken off the mosaic, amplified, ligent reader, having scanned a few does it work? and broadcast. magazine articles and news stories about Let me begin with the last question. A The analysis, or "scanning," is accom television, has arrived only at the point convenient definition of television is "the plished by a beam of electrons originat of confusion. Perplexing questions pop transmission of scenes or images in mo· ing in the neck of the Iconoscope and into. existence, speculation arises, and tion, by electrical communication meth focused on the mosaic to the fineness of nobody seems very certain of anything ods." Broadly, it is a radio medium a pin point bi' an electrostatic lens. The about television. TelevisiOli is bound to designed for the entertainment and beam is drawn across the mosaic, by have profound effects on our social or education of the home audience. The horizontal and vertical deflection coils, der. It will affect existing industries, television system which has gained wid· in a predetermined pattern of 441 lines create at least one new one. Some dav est acceptance is entirely electronic, at the rate of 30 frames a second. Ac it may encroach on other entertainmen't without a single moving mechanical part. tually the rate of scanning is 60 half and educational media. Perhaps it will Its bright, ml)ving images are in black frames, or "fields," Per second. Inter cause a change in the styles of presen- and white, filled with interesting detail lacing-scanning of the odd lines dur- 207 © 1939 SCIENTIFIC AMERICAN, INC 208 SCI E N T I FIe A;\1 E RIC A N APRIL - 1939 tors and cameras are located in the film studio. All technical equipment has its limita tions. Television apparatus offers no ex ception. Our camera's depth of focus still leaves something to be desired, although improvements are constantly being made in this respect. Likewise, the spectral re sponse of the Iconoscope is not equiva lent to that of the human eye, though its range is considerably greater, since it extends into the infra-red frequencies. In a more practical sense, television service at present is limited to a few transmitting stations_ NBC has been broadcasting intermittently with the RCA all-electronic system of television since June, 1936. Several other stations employing the electronic system, how ever, will soon be broadcasting. One other station is licensed in New York City, another in nearby New Jersey and two others upstate. Bridgeport, Connecti cut, will be the location of a sixth eastern Mobile television unit consisting of station. Most of these will be isolated two trucks that carry all equipment stations, although I believe the two in necessary for relaying television pro upstate New York will be interconnected grams from remote points to the main transmitter located some miles away by radio relay. THIS brings us squarely against the ing the first field, followed by the even problem of television networks_ If numbered lines in the second-complete television is to fulfill even a small part I y eliminates flicker. of its promise it must create networks. In so scanning the mosaic, the electron Spontaneity will be the life blood of tele beam neutralizes the charge that has vision, and it cannot deliver news events accumulated on each element of the to viewers in many cities, while they are mosaic_ In so doing, the beam sets a still happening, without building net current flowing in the circuit; in aggre works. Eventually, I am sure, the coun gate, these impulses constitute the vision try will be covered with such networks ("video") signaL They are amplified in much the same manner as radio net many times and sent to the transmitter works reach into all parts of the United either by radio relay or coaxial cable, States today. Economic considerations where they modulate the station's ultra also make the creation of such networks high frequency carrier before being imperative, but technical and cost prob broadcast over a specially designed wide lems still limit our progress in this direc band-pass antenna system_ tion. Most circuits comprising our na At the receiver, after again being am tional sound radio networks cannot Mr_ Hanson, author of the accom plified, the video signal modulates the panying article, with one of Icono transmit sound frequencies beyond 5000 electron beam in the neck of a large seope tubes used in transmission cycles. Good television demands circuits funnel-shaped vacuum tube called the capable of transmitting a band of fre Kinescope_ The modulated beam is quencies from 30 to 4,000,000 cycles per drawn over a fluorescent screen of zinc . film- programs, and a mobile television second for the video signal alone. sulfide at the large, or screen, end of the station for outside pick-ups_ This latter Two methods are available. The co tube in the predetermined pattern of 441 should be of great assistance to us in axial cable, a concentric conductor lines, 30 times a second_ And since the presenting programs from athletic sta capable of passing the wide band of light values created in the fluorescent dia, parades, and sidewalk interviews, frequencies used in television, is ap screen vary directly with the intensity of and all types of outdoor news events, in parently the new art's equivalent of the the electron beam, a replica of the orig addition to floor shows from popular wire circuit used to interconnect sound inal image is produced_ Viewing is either night clubs and hotel grill rooms_ We broadcasting transmitters. One such ex direct from the end of the tube or by shall use either our present mobile sta perimental circuit, connecting New York reflection in a mirror_ tion, or one similar to it, in televising the and Philadelphia, is already in existence, This is the system we shall use in in next Presidential Inauguration in Wash although some modification of it would augurating our television program ser ington, D. C- be necessary if we were to transmit 441- vice in the New York area. We are con Our studio for live talent programs is line images over it. Its cost, I understand, fident that with the inevitable technical fitted with three Iconoscope camera was about $5000 a mile. The other possi improvements that will develop once a chains for multiple camera pick-up of bility for networking is the use of au television service gets well under way, performances_ This assures the variety of tomatic beamed micro-wave radio relays the system will serve the needs of the shots necessary in the pictorial art. which, in tests, have given us reason to American people_ Switching from one camera to another suppose that they will be at least an im Our technical facilities at W2XBS in is done in the studio control room by portant element in the final answer to clude studios for both live talent and means of push-buttons.