The Estimation and Forecasting of Short-Wave Propagation Conditions, with special reference to Naval Communications

The paper describes the development and application of techniques for the use of ionospheric data in the solution of high-frequency communication problems, during the years 1941¿1945, at the Admiralty Signal Establishment. An account is given of the investigation of the computation of ionospheric absorption, and of the technique developed for the determination of lowest usable high frequency based on this investigation. Semi-empirical expressions are derived for ionospheric absorption for both short- and long-distance transmission. The formulae were found to fit well with existing ionospheric absorption data. A brief summary is also given of the general underlying principles of ship-to-shore communication. Using ionospheric methods, charts were developed to enable ships to choose the optimum frequency of transmission or reception with a given base. Charts were constructed for special services, and also for general use, embracing the whole network of naval shore receiving-stations.