The phenomenon of a train of optical fibre solitons, modulated in some way by impressed disturbances, is increasingly being identified as a new type of dynamical system, with interesting dynamical behaviour which can be studied both experimentally and mathematically. This perception leads rather naturally to an investigation of the behaviour of this system when subjected to various forms of pulse-analogue modulation, to which this chapter is devoted. The principal motivation for the study of solitons in pulse position modulation (PPM) arises from the fact that PPM with short pulses permits a greater transmission rate than longer pulses, and intense pulses exhibit higher signal-to-noise ratio than weak pulses. Consequently, intense short pulses are desirable for PPM, but fibre dispersion limits the minimum width an individual pulse can have after linear transmission. This consideration leads naturally to speculation on solitons in PPM because the soliton does not suffer dispersion. However, this is only one example of a general interest which is developing in the understanding of dynamical phenomena involving solitons, to which this work is addressed.