Radio Broadcast (May-Oct 1925)

26 Radio Broadcast Boston will recall hearing mysterious buzzes accompanied by clicks occurring at intervals of a little more than a second apart on a 200 meter radio wave during the month of December, 1922. Many inquiries were answered by explaining that "special tests on radio control were being conducted." Probably no one had the slightest conception that pictures were being sent over the air. It was from the experimental radio station Ixm, located at the Institute, that the pictures were transmitted. They were received in Dr. Hainsworth's laboratory, not far distant. The quality of the received pictures was poor, but the work must be given considerable credit, for it was probably the first time that the synchronizing of the receiver with the transmitter was accomplished by radio. The development work on the phototelegraphic system was conducted in Dr. Hainsworth's laboratory and radio station Ixm where Mr. Cooley spent most of his time. In the summer of 1923, the first tests on the new system designed by Mr. Cooley were made in this radio "shack." It is seldom that apparatus of new and unusual design meets its builder's expectations. Mr. Cooley was prepared to be disappointed. But on the contrary, unusual and encouraging results were obtained. With the aid of a colleague, Mr. R. A. Cunningham, Mr. Cooley rushed along the construction work on a complete set of apparatus to be used for demonstration purposes. Dr. Hainsworth left Boston during the summer of 1923 to take up some other work in Seattle. Since that time he has not been able to take an active part in the development of the phototelegraphy system for which he is responsible. AT THE RADIO BROADCAST LABORATORY \A7HEN Arthur H. Lynch, editor of this * V magazine, was asked to assist in obtaining laboratory space for the development of the Cooley phototelegraphic work, he was quick to realize its possibilities. Without the slightest hesitation he freely offered the facilities of the Radio Broadcast Laboratory for the test of Cooley's ideas. Accordingly, night and day, and with this precious equipment constantly under the eyes of watchmen, Cooley pursued his tests of a high speed phototransmission device for reproducing at distant points photographs having all the shades necessary to make up a perfect picture. It was not until after the International Radio Broadcast Tests in December, 1924, that the various units of the new Cooley phototelegraphic system had been properly coordinated and it was possible to send pictures of satisfactory quality in the Radio Broadcast Laboratory. Arrangements were made to loop the picture signals through two local telephone exchanges and to return them to the Laboratory, where both transmission and reception might be watched by the operators. The transmitter was connected to a telegraph line which terminated at the Radio Broadcast office. At this point, the signals were acoustically transferred to a telephone which was connected to the private branch exchange of Doubleday, Page & Company. This private branch exchange was in turn connected to the Garden City telephone exchange, where the usual telephone connections were set up for the wire which serves the Laboratory telephone. success on the first test IN THIRTY minutes ten pictures were transmitted. The apparatus was readily synchronized within ten seconds before the reception of each picture began. The pictures transmitted were taken from magazines and rotogravure sections of newspapers. In the receiving apparatus, the pictures were printed out on an inexpensive photographic paper that required developing and fixing before the image could be seen. The thirty minutes mentioned included the time required for this work. The quality of the received pictures was fair, in spite of a defective device in the transmitter. This device was the photoelectric cell, a necessary part of the equipment. Air had leaked into it and caused its action to be sluggish. A new one is now being built by Dr. Kunz, especially designed to meet the high speed requirements in this system of phototelegraphy. The limitations of the Cooley system are unknown. It is probable that a commercial type model, which can handle four hundred messages an hour, will be constructed within the next year. Compare this with the present machine-printing telegraph, which averages about fifty messages an hour. Using the Cooley design, the transmitter or receiver is neither bulky nor expensive to construct. In a commercial embodiment planned for an early date, a portable transmitter will be built for the use of newspaper photographers. It will be necessary only to connect the machine to the electric light socket, get the newspaper office by telephone, and place