A system for synchronizing stations in a communications network comprising: at least one airborne or space-based vehicle; and at least two stations, each station having receiver means in data communication with the at least one airborne or space-based vehicle and control means in data communication with the receiver means and in control communication with a communication means. When each receiver means receives a synchronization signal from the at least one airborne or space-based vehicle each receiver means forwards the synchronization signal to its respective control means. The respective control means processes the synchronization signal to determine the operational frequency required by its respective communication means to maintain or establish communication with the other station. The respective control means also operates to control its respective communication means to change to the determined operational frequency.