The dynamical behaviour of infinite periodic trains of optical fibre solitons subjected to modulation of the position of each soliton is studied by analytical methods. It is concluded that multigigahertz pulse-analogue transmission over amplified links many times longer than the linear dispersion limit at high signal-to-noise ratio is achievable. The principal limitations are the nonlinear intersoliton interaction and amplifier spontaneous emission. The analytical techniques developed are useful for the study of a wide range of modulation and noise phenomena in soliton pulse trains.