The Power Spectrum of a Digital Signal

An analysis of the spectra of digital signals is presented that includes Lundquist's and Glance's results for PSK signals as special cases while at the same time being much simpler than previous analyses. The signal is assumed to be modulated in phase and/or amplitude by a sequence of pulses that may have different shapes for different symbols. In addition, the pulse representing a given symbol may be affected by neighboring symbols, so that intersymbol interference in the modulating process is permitted. The results, nevertheless, take a simple form, and they are applied to two binary cases.