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.