Impact of Group Delay Ripple in Transmission Systems Including Phase-Modulated Formats

We derive an analytic expression for the signal distortion that results from the effects of group delay ripple. When reduced to its simplified, first-order form, our expression provides a clear physical picture of how the signal is affected by the ripple. We find that both the signal distortion itself and the Q-factor penalty associated with it are dependent on the ripple period and magnitude, and on how the mean signal frequency is located with respect to the ripple peaks. We also find the penalty to be dependent on the temporal profile of each "one" and on the phase relationship among the "ones."