Mutual radio interference in H.M. ships

The purpose of this paper is to outline the subject of interference to and from radio and radar installations in H.M. ships. Interference caused by machine-generated radio frequencies is not dealt with, as this type of interference is not greatly different in ships from similar conditions elsewhere. The general principles involved in avoiding mutual interference caused by simultaneous transmission and reception in the same ship have been well known for many years, and these principles had been enforced in the design and installation of radio equipments in H.M. ships prior to 1939. During the war these principles could not be maintained, owing to the necessity to fit commercial equipment, and, with the coming of radar, interference became worse than anything previously experienced. To ameliorate these conditions without drastic re-design of the offending equipment, various expedients had to be devised which are here described.