Cooperative study of radio fading

Radio progress depends upon an increasing knowledge of the vagaries of radio-wave transmission. Radio transmitting and receiving devices have been highly-perfected, but received signals are still subject to variations and distortions. In order to secure data on the causes of these variations, the bureau invited a number of university and other laboratories to cooperate in their study. The principal work was the conducting of special radio transmissions from broadcasting stations, during which all the laboratories made simultaneous graphical records of fading.