Projection engineering (Sept 1929-Nov 1930)

Page 16 Projection Engineering, June, 1930 Fig. 2. Tuning in on television program. a large case below for the batteries. In front of the camera case is the revolving scanning disc, driven by a large synchronous motor, together with the photographic lens. The image is focused by means of a peep tube at one side of the lens. The camera may be tilted to any angle by a screw handle, while the entire mechanism may be moved about on the four rubber-tired wheels of its truck. A control board serves to start and stop the motor, vary the electrical adjustments, and otherwise regulate the mechanism. The subject to be picked up by the television camera is fully illuminated. The usual motion picture lights may be employed. However, it is interesting to note that the photoelectric cell critically interprets the slightest differences in illumination. While the human eye and again the photographic negative may not draw very fine distinctions between slight differences in illumination, the photoelectric cell shows clearly the variations, and, indeed, accentuates them. Thus the most troublesome dark spots may appear in the reproduced radiovision image, and yet when the original is viewed in its full illumination, there appears to be no reason for such effects. However, the engineers have now become accustomed to the critical gaze of the photoelectric cells and know how to adjust the illumination accordingly. The direct pickup, with full illumination, is a decided step ahead in the commercial exploitation of radiovision. It serves to provide an endless flow of fresh television material. In the absence of a permanently recorded program, as in the case of film pickup, the radiovision broadcaster is certain to provide greater subject matter interest. Anything serves as program material today. Any person, stepping before the camera, is flashed over the air, and so there need be no dearth of material even though some of it may be prosaic in everyday terms. Increased Variety of Subjects However, the main advantage of the direct pickup camera with full illumination is the greater variety of subjects than is available with the scanning beam method. It now becomes possible for radiovision broadcasters to go out in the field and select news subjects, prominent personalities, and so on. Now let us not misunderstand what this means : this is not a promise that baseball games, automobile races, horse races, football games, parades and so on will be placed on the air shortly. Anyone, even with a modest knowledge of radiovision technique, knows how utterly impossible it is to radiovise such events for a long time to come. However, it is possible, now, immediately and practically, to pick up a close-up of a person and to broadcast this image at the same time that the microphones of the regular sound broadcasters are picking up that person's voice. For instance, what is to prevent the properly equipped radiovision broadcaster from picking up the closeup of Admiral Byrd as he sails up New York Harbor, or Colonel Lindbergh upon his return from some distant flight, and so on? The close-up of our President may be broadcast at the same time that his voice goes forth over the broadcast networks. All that is required is a television camera out on location, so to speak, with the radiovision transmission either by remote control over wire lines to the usual transmitter, or, better still, by a portable transmitter. These things are, please note, no longer pipe dreams. They are realizable realities. It is just a question of initiative on the part of radiovision workers. Something has been said about the radiovision pickup of subjects which are being broadcast over sound broadcasting systems. This is an ideal tieup, for obviously the sound end of radio transmission is fully established and perfected. By tying in with sound, the radiovision program is made immeasurably more effective. Even though the pictures may lack in detail, the sound accompaniment serves to carry them along and to make for better understanclability. Standard Films and Discs Several months ago, the Jenkins staff undertook simultaneous and synchronized sight and sound broadcasting by means of standard talking picture films and discs. The subjects were recorded and filmed under typical "talkie" studio conditions. The film was placed in the Jenkins film pickup machine, to which was connected the 33% r. p. m. turntable by means of a flexible shaft. Thus the pictures and sound record were in step at the starting tape. The picture signals were transmitted via the Jenkins transmitter W2XCR at Jersey City, N. J., while the sound signals were transmitted over direct wire to the DeForest experimental radio telephone transmitter, W2XCD at Passaic, N. J., for transmission on 187 meters. Fortunately, most broadcast receivers reach down that low, so that with a standard broadcast set tuned to W2XCD, and with a short-wave receiver and radiovisor tuned to W2XCR, the average home could enjoy complete sight and sound broadcast reception for the first time.. Only a few weeks ago, the Jenkins organization opened a television theatre in connection with the Radio and Television Week of the Jersey City Chamber of Commerce. The television theatre, held in the Lodge of West Side Park of Jersey City, took the form of a combination sound and radiovision studio. The Jenkins camera, surrounded by powerful motion picture lights, served for the picture pickup, while one or more microphones picked up the sounds. The theatre had much the general atmosphere of the usual "talkie" studio, although on a more modest scale. Various prominent stage, lecture platform, publiclife and other personalities appeared before the combined radiovision and sound broadcast pickups, and were flashed to a number of receiving devices placed about the city, as well as to an unknown number of "lookersin" scattered far and wide. This demonstration served to prove the subject matter interest which is possible even with the admitted limitations of the present 48-line technique. How Much Detail? And speaking about limitations, just how much detail is possible? Actually, the detail possible with a 48-line pic