Power spectrum of unbalanced NRZ and biphase signals in the presence of data asymmetry

The impact of data unbalance and asymmetry on the power spectral density of nonreturn-to-zero (NRZ) and biphase baseband modulations is presented. Previously reported results for this problem assumed an incorrect model for the shape and number of elementary pulse shapes that characterize an arbitrary random data stream and thus led to erroneous computations of these power spectra. This paper provides the correct analytical model and then use it to obtain theoretical power spectrum results that are in full agreement with those obtained from computer simulation.