Spectral characterisation of offset pulse position modulation

Offset pulse position modulation (PPM) has been shown to be more attractive for use in optical fibre channels than on-off keying, digital PPM and in some respects multiple PPM in some applications. However the spectral analysis of this coding scheme has not yet been addressed. In this study the authors present, for the first time, the spectral characteristics of an offset PPM sequence. The results show strong frequency components at the frame rate and, if return-to-zero pulses are used, the slot rate.