Technical Digests - Transoceanic Radio Telephone Development

EN years have elapsed since the opening to public use on January 7, 1927, of the first long distance radio telephone circuit. This form of intercontinental communication has now come into practical business and social use. A network of radio circuits interconnects nearly all the land wire telephone systems of the world. The art has passed through the pioneering stage and is well into a period of growth. The technical side of this development, which the present paper reviews, divides naturally into four categories. The first covers those factors which made possible the beginning of commercial radio telephony. 1 In the second are the things without which its rapid growth and wide expansion could not have occurred. In the third, are a few incidental but interesting or valuable technical features. The fourth considers future improvements now in view. ESSENTIAL INITIAL DEVELOPMENTS Radio telephony presents difficulties in addition to those existing in radio telegraphy because: (1) The communication is two-way, and the radio system must be linked in with the wire telephone systems and available to any telephone instrument; (2) The subscriber cannot deliver himself of his message until the connection is actually established, and on this account delay due to unfavorable transmission conditions is less tolerable; (3) The grade of transmission required to satisfy the average telephone user is higher than that tolerable in aural tone telegraph reception by an experienced operator. These requirements emphasized the need for accurate and quantitative knowledge of radio transmission performance as a basis for engineering radio telephone systems.