Numerical calculations concerning pulse position-modulated (PPM) infinite (periodic) and finite trains of bright pulses in a single mode optical fibre are presented. Use is made of an inherent feature of the beam propagation method which yields truly periodic solutions. The solitons are organised into unit cells containing various numbers of solitons, and phase differences are permitted between them. A comparison between the behaviour of a group of solitons in a unit cell of a periodic train and the same number of solitons, standing alone as a group, is made. Generic plots for the maximum temporal displacement against the position-modulation coding parameter are presented for both 8 and 16 bit patterns.