Power spectra of digital p.m. signals

A formula of Shimbo et al. for the power spectrum of signals pulse-modulated in accordance with random sequences is specialised for Markov chains. In the analysis, z transform techniques are used rather than explicit matrix methods. The resulting expressions may be used to find the spectra of a wide class of digital signals obtained by pulse modulating the amplitude, frequency, phase, or any combination of these, of a radio-frequency carrier. Attention is directed to phase modulation and, in particular, to ideal phase reversal and signals which practical systems might produce as approximations to it. In the first such signal, amplitude modulation is introduced in addition to the phase modulation, while in the other there is a nonzero switching time between the two phase levels. The power spectra of these signals are determined and compared with the phase reversal spectrum.