Clock synchronisation for mobile radiotelephony

The case for the use of pulse-code modulation for radiotelephony is summarised. The nature of the problem of achieving clock synchronisation for a time-division-multiplexed/pulse-code-modulation system with mobile terminals is discussed. The problem is first shown to be soluble under the ideal (noiseless) conditions of a perfectly synchronised slave-clock system. Noise in the system has two deleterious effects. It may cause two mark indications to be fed into the system where only one exists, this effect can be eliminated by circuitry arrangements. It may also cause a mark indication to vary its position in the time frame from frame to frame, this effect can be overcome by a clock-phase reversal at a mobile terminal. The parameters used in an experimental system are included as an Appendix to the complete paper.