Abstract :
The paper forms the first part of two papers on efficiency and reciprocity in pulse-amplitude modulation. A method of converting a low-frequency signal into a modulated pulse train and back again, with low power loss, provides multiplex communication on a 2-wire basis, without amplifiers. In principle, lossless 2-way channels with a bandwidth of half the sampling rate are feasible. The paper furnishes a theoretical study of the transmission properties of such channels.
