Radio Broadcast (May 1928-Apr 1929)

OCTOBER, 1928 TELEVISION— ITS PROGRESS TO-DAY 333 Station wrny of New York has installed a television transmitter and are transmitting programs through their regular broadcasting station and their short-wave station, as indicated in Table 1 . According to a recent release from the Westinghouse Electric and Manufacturing Company, the experimenter will soon be able to look to the station this company operates for programs of radio movies — it will be noted from Table I that this company has obtained an experimental license. A demonstration of radio movies was held in Pittsburgh on August 8th — a demonstration which we, unfortunately, did not see. The system used was in one respect at least, unusual: a mercury arc lamp, magnetically controlled by the incoming signals, we understand, was used in place of the neon tube, the advantage being that much more light can be obtained from the arc than can be obtained from the neon tube so that brighter images are possible. The neon tube doesn't give any too much light. On the other hand, it seems likely that the arc will be more expensive than the neon tube. Incidentally, the statement in the Westinghouse release to the effect that the demonstration held August 8th, 1928, "was the world's first demonstration of radio movies and posSibly the most astounding of the many advances in the science of radio announced in the past year," is rather surprising since, as mentioned previously, FIG. I. HOW JENKINS CONTROLS THE DISC SPEED Jenkins has been transmitting radio movies ever since July 2nd. Furthermore, in the May, 1927, issue of the Bell Laboratories Record we read, among other statements, that during research in television, "a strip of motion picture film was projected from a standard machine upon a photoelectric cell. The moving picture of this film was then re-created for an observer by receiving equipment involving a suitable neon tube and a scanning disc." But whether first or last the Westinghouse tests are of interest to experimenters as another possible source of television signals. APPARATUS FOR RECEPTION HpABLE 1 sums up the situation with as com* plete a list as could be obtained of those who expect to transmit television signals. The table also gives the data one must have in order to receive the programs. In this connection the important facts are the number of holes required in the scanning disc and the speed of the disc. The column headed number of pictures per second is equal to the speed of the disc in r.p.m. divided by 60. The table shows, among other things, lack of cooperation for as many as five different scanning discs (or one scanning disc with five sets of holes: 24, 36, 45, 48, and 60) would be required to receive all of the stations. A complete television receiver consists of a tuner, which may be any ordinary broadcast band or short-wave set depending upon whether the signals to be received are being transmitted on the broadcast or short-wave bands. Strong signals are required for the operation of the neon JENKINS SCANNING DRUM This view of the scanning drum shows clearly the quart^ rods extending from the holes in the surface of the drum to the neon lamps in the center. The wire connections to the four-element neon lamps are seen at the right tube. As a basis of comparison we might say that the signals should preferably be strong enough to load up a 1 7 1 a tube with 180 volts on the plate and a 40volt C bias. If a transformer-coupled amplifier is used, three stages instead of two may be necessary unless the signals are good and loud. A three-stage resistance-coupled amplifier is preferable, however, especially as quality improves. An amplifier of this type properly constructed will pass the higher frequencies which would be cut off by a transformer-coupled amplifier. The cost of a television receiver disc neon lamp and motor will vary, depending upon the parts used. Forty or fifty dollars should cover it in all cases. Table 2 shows the companies which are at present manufacturing apparatus for use in television reception. Complete details for the construction and operation of a television receiver are not given here, but will be the subject of a future article. In these pages we have aimed merely to make clear for the readers of this magazine the present status of experimental television. CONCLUSIONS IN RESULTS, none of the demonstrations 1 which we have seen, possibly with the exception of those by the American Telephone and Telegraph Company, first held on April 7, 1927, produces pictures which hold one's interest for any length of time. The present appeal of the art is not one of receiving good pictures, but is to do at home — all by oneself — what is demonstrated in the laboratories of a large corporation with the aid of a thousand engineers, and a million dollars worth of apparatus. When one sees such a demonstration, its greatest appeal — of doing it oneself — is lost, and there remains nothing but comparatively poor reception of the image of a person, made pink-faced because of the characteristic glow of the neon tube in the receiver. Television, then, is still the province of the experimenter, the man who likes to do h s own pioneering. And to the experimenter it should be among the most fascinating of all the fields of modern scientific advance — because its possibilities are so vast, its perfection so tenuously in the future, and its technique so amenable to new ideas and new ways of doing things. And what does the experimenter, the scientific enthusiast, get out of it? To the world at large, perhaps, pep and a hearty laugh are the attributes of the stock promoter, a fish-tail handshake and absent-mindedness the concomitants of the scientific outlook. Such views, however, must be held by persons who have never been on the inside. The scientist and experimenter get as much fun out of peeping through a spectrobolometer (a device for measuring the energy associated with a spectrum) as does the baseball fan when he catches the ball that Babe Ruth knocks into the stands. They merely get their joy out of life in different ways. C. Francis Jenkins is a shining example in the field of television of the man who is carried on by the sheer joy of being on the inside of a great development. He is sixty years old, and has been working some twenty-five years on photo broadcasting, television and a host of other things, yet he still retains an enthusiasm which seems to charge his whole staff. Jenkins' attitude, that of getting a thrill out of working with something new, and putting together stuff that frequently utilizes some gadgets from the junk box, is that of a born experimenter. Do you want to experiment with television? Then answer this question: Can you get a kick from twisting dials and rheostats for a couple of hours to get finally some fleeting, perhaps hardly recognizable image in the viewing window of a scanning disc? Or do you have to see the previously mentioned Babe Ruth knocka homer to get a thrill? Although the cases aren't exactly synonymous, think of the thrill Galileo got out of looking through his glass — the first telescope. As a young lad, Galileo used to watch the candelabrum in the cathedral swing slowly to and fro; he timed its motion by the pulse beat in his wrist, and thought of using such a device for the measurement of time. In later life he invented the telescope, and with it saw thousands of stars never before seen by man. In 1610 he wrote to Kepler: "Oh, my dear Kepler, how I wish that we could have one hearty laugh together! Here, at Padua, is the principal professor of philosophy, whom I have repeatedly and urgently requested to look at the moon and planets through my glass, which he pertinaciously refuses to do. Why are you not here? What shouts of laughter we should have at this glorious folly! And to hear the professor of philosophy at Pisa laboring before the Grand Duke with logical arguments, as if with magical incantations to charm the new planets of the sky." Some joy is surely to be derived from doing what hasn't been done a thousand times before. TABLE II: WHO IS MAKING TELEVISION APPARATUS Name of Manufacturer Apparatus Daven Corp. Insuline Corp. of America National Co. Raytheon Mfg. Co. Interstate Electric Co. Motors, scanning discs (either 24, 36, or 4& holes), neon tubes, rheostats for controlling motor speed, completely assembled resistancecoupled amplifiers. Complete kit for about $45.00 Complete kit listing for $52.50, containing scanning disc with either 24, 36 or 48 holes, motor and control apparatus, magnifying lenses (to make the picture appear larger), hardware 48-hole scanning disc. Price: $15.00 Kino Lamp. A neon lamp with TJ" plates for use in television receivers. Price: $12.50 Type M2V Baldor television motor. Price: $23.00