On Asymmetric Telegraphic Spectra

It is shown that single side band Morse transmission, if practicable, would relieve the present long-wave spectral congestion. Methods are developed whereby the wave shape of the single side band signals can be visualized when the original message envelope is given, and it is shown that the prolonged transmission of true single side band signals would in general necessitate the radiation of infinite amplitudes. Wave forms of approximations to single side band signals which evade this difficulty are determined: the wave form of the original message can be recovered without distortion from these "asymmetric side band" waves, the use of which, however, requires more power and also greater crest amplitudes than normal double side band transmission. The production and reception of asymmetric side band waves is discussed. The subject is treated de novo, and the paper therefore overlaps considerably that of H. B. Nyquist† in which many of the present conclusions were obtained by slightly different analytical methods.