Communications system with contention protocol

摘要

A communications system for data acquisition and control is provided, communicating on a time-division multiple- access communications channel, such as a radio channel. Time on the channel is divided between first periods (contention time) during which a central station 10 receives signals from remote stations 11 and second periods (polling time) when signals are transmitted to the remote units to grant access to the channel. Means are provided for transmitting a signal to the remote units to inform the remote units of a change in the length of at least the first periods of time in response to traffic measuring means.