SEED AND ORGANISATION OF OSCILLATORS IN DIGITAL TELEVISION BY OSCILLATORS IN ANOTHER TELEVISION

摘要

A method and apparatus are described synchronizing oscillators at the network junctions in a pulse code modulation (PCM), time division multiplex (TDM) telecommunication network. In each network node pulse trains of clock pulses are received via incoming lines, and corresponding clock pulse trains are produced in the network node in accordance with the node's clock frequency division factor. The received and locally produced pulse trains are phase-compared, and a control signal resulting from the comparison is used to control the frequency of the clock oscillator in the network node. In each network node of a first network which has a direct line connection to a network node in a second network a phase comparison takes place between the two networks, and the result of the latter comparison is compared with the result of an intra-network comparison. The result of the latter comparison is used to adjust the line clock frequency of a given network.