The transmission characteristics of asymmetric-sideband communication networks. Part 2

This paper, in continuation of Part 1, which has already been published in the Journal,1 deals with the transmission of an amplitude-modulated wave through a bandpass channel the transfer characteristics of which are not symmetrical, either in modulus or phase, or both, about the carrier frequency. This paper is not concerned with any specific application of such asymmetric-sideband working; perfectly general forms of modulating wave and channel characteristics have been assumed. The theorem, given in Part 1, expressing the ¿equivalent modulation frequency characteristics¿ of such a channel in terms of the bandpass characteristics is here considered in greater detail. The idealized transfer characteristics chosen by various authors for analysis of asymmetric-sideband channel distortion are examined in the light of this theorem, as are also the characteristics of a generalized tuned circuit amplifier stage (or series of stages), taken as a practical example. The theorem is again extended to include the case of a carrier wave modulated by an envelope wave which rises or decays at a rate greater than that of the carrier itself (that is, a wave spectrum containing ¿negative¿ sidebands). An appendix is included, giving some notes on the waveform of such a modulated wave.