Radio telephony between moving stations

This report describes the application of radio communication to duplex telephony wherein one or both of the correspondents is in motion. The examples given are - speaking with liners, small ships, air liners and trains; the evolution and technical details are described in each case. Progress appears to lie along the following lines: Marine duplex telephony on a single wave-length is already a fact (accomplished on the "Olympic"). The use of waves below 10 m. is imminent, and has already been tried for the guidance of boats on rivers and in harbours. In this connection the "micro-ray" system, already tried (with 14 cm. wave-length) between Dover and Calais, may be applicable to ship communication in certain circumstances. Aviation. - The tendency is to increase lightness and robustness of equipment rather than its power; also to use higher receiver amplifications. The limited size of the apparatus for the micro-ray should make it specially advantageous in this field.