Radio Broadcast (May 1928-Apr 1929)

A RADIO MOVIE DEMONSTRATION Dr. Fran\ Conrad, Assistant Chief Engineer of the Westinghou.se Electric and Manufacturing Company, with the transmitting apparatus with which he recently demonstrated the radio transmission of moving pictures. At the right is the light source; next to it are the scanning disc and focusing lenses; at the left are the film reels and (in the cylindrical can) the photoelectric cell Television — Its Progress To-day By HOWARD E. RHODES Radio Broadcast Laboratory TT I KE the search of the ancient philosophers for the elixir of life, television has ^ been for years an inspiriting dream of man. Although its first fruits in experimental demonstrations have been shown only in the past few years, the principles on which these demonstrations have been built have been work of several generations of scientific endeavor. The scanning disc, for example, which is an essential part of all the systems being utilized in this country to-day, is the invention of Nipkow, and dates back to 1884. To a considerable extent the problems which it was necessary to solve to make the recent demonstrations possible have been associated with the applications of already known principles, but the future development of the art will be the result of research — the systematic pursuit of knowledge — or the result of some new television tool, and it seems likely, to the writer, that such is necessary to make television really practical. Enough has already been done in television, however, to excite the interest of everyone. Some stations are now on the air with television, and some are getting ready to go on, so that dyed-in-thewool experimenters will find it hard to resist the temptation to set up apparatus to receive the broadcasts — even though their quality and program interest is negligible. For the benefit of these experimenters, and also for those interested only in the thrill of "looking in," we here report the progress of television in this country to date. The questions that immediately pop into one's mind — how good are the results, what stations are transmitting, how much does the receiving apparatus cost — are answered as fully as possible. In order that the article might be written with a background of experience, the past few weeks have been spent collecting data and personally seeing several demonstrations. TELEVISION DEMONSTRATIONS THE first television demonstration seen by * the writer which showed promise of being applicable to home use was the demonstration by Dr. E. F. W. Alexanderson at the Schenectady JIJGV JN THE July and August issues this magazine published two articles by Mr. R. P. Clarkson which set forth quite clearly the fundamental problems associated with television. By no stretch of the imagination could Mr. Clarkson be considered optimistic in his outlook, and by some he is probably considered decidedly pessimistic in regard to the present methods of approach to the problems of television. It should be realised, however, that Mr. Clarkson was writing from the point of view of one who wished to bring this science from Us air-castle fancies back to terra firma. The present article has a different purpose. It is the result of a careful survey — in many cases, by personal visits — of the stations now broadcasting, or about to broadcast television, and its aim is to give the reader information on who is doing the work, how it is being done, and what results have so far been accomplished. — The Editor. plant of the General Electric Company. This company through three of its stations is now transmitting television signals in accordance with the schedule given in Table 1. The receiver in this demonstration consisted of a scanning disc with a neon tube back of it, the disc being turned by a motor and manually synchronized by varying the resistance of a rheostat. Essentially similar apparatus was used for part of the American Telephone & Telegraph Company's demonstration, with the difference that synchronization in the latter case was accomplished by means of synchronous motors — a more scientific method of holding the receiver in step with the transmitter, but also much more expensive. To the Telephone Company television constitutes a method of communication complementary to the telephone, and its interest is to develop a system giving quality reproduction. Therefore it cannot consider any system in which synchronization is not positive and automatic. In the same classification fall the more recent tests of this company in which actual outdoor events were televised. The apparatus used was entirely beyond the scope of the-experimenter. The experimenter must depend upon other sources for television signals — and who knows but that some interesting results might come from his work. Even the greatest are sometimes caught napping! More recently we saw a demonstration at the laboratory of the Daven Company, which has employed Mr. P. H. Kober, a former associate of Doctor Alexanderson, to develop television apparatus for them. In the Daven laboratory, a complete television transmitter and receiver have been constructed, similar in operation and results, so far as the writer can see, to that demonstrated at the General Electric Laboratories. Synchronization of the receiver with the transmitter is accomplished by means of a rheostat in series with the motor, across which a push-button switch is placed. The resistor is adjusted so that the motor tends to turn at slightly below the correct speed; pressing the 331