Application of Phase-Locked Oscillator for PCM Network Synchronization

In PCM integrated communication systems in which PCM telephone signals are transmitted and switched in an integrated manner, the clock frequency of the PCM signals in the whole network must be synchronized. Mutual synchronization was proposed for this purpose. This is an important application of a phase-locked oscillator. By interconnecting two phase-locked oscillators to control each other, the frequency of the interconnected system will be the average of the free-running frequencies of the two oscillators. By interconnecting a number of multiple input phase-locked oscillators, all the oscinators can be synchronized. The synchronization system based on this principle is called mutual synchronization and various versions of mutually synchronized systems have been proposed. Since the interconnected system of phase-locked oscillators includes many positive and negative feedback loops, to design a system, the dynamic as well as the static behavior of the system should be carefully analyzed. This paper describes the principle of various versions of mutually synchronized systems and the results of analyses on the dynamic and static behavior of mutually synchronized systems.