Local area networks.

摘要

A data transmission network includes a number of access controllers (10) connected to a central hub (12). The hub includes an arbitrator (54) to select only one access controller for data transmission. Upon selection of one controller all other controllers are disabled to prevent collision of data packets. An interlock (42) prevents enablement of a disabled controller until the data packet received by the transmitter has terminated to prevent transmission of part of a data packet. Synchronisation between the data and a master clock (166) is obtained by an initial coarse synchronisation and a subsequent fine synchronisation. The coarse synchronisation is obtained by generation of a number of identical signals with a time delay between each signal. A clock pulse latches to one of the signal paths to provide the initial coarse synchronisation.