Intersymbol Interference in Pulse-Amplitude Modulation Signaling Systems Satisfying a Spectral Mask Constraint

The Space Frequency Coordination Group (SFCG) has recently recommended a set of restrictions on the power spectral densities of space-to-Earth telemetry signals, which may apply to signals sent from Mars to Earth by future JPL missions. These restrictions take the form of spectral “masks” restricting the shape of the power spectral densities. In this article, which is semi-tutorial, we investigate the impact such masks have on the issue of intersymbol interference. For example, we shall give a necessary and sufficient condition for a given spectral mask to be compatible with non-intersymbol interference, i.e., Nyquist, signaling. We shall also see that the important class of root-raised-cosine Nyquist pulses is compatible with the current SFCG recommendations.