Remote control population warning system - has transmission channel divided into wideband and narrow band channels used in opposite directions

摘要

The system a large number of remote control stations from which terminal stations can be reached through a remote control network with transit nodal stations, end nodal stations and local nodal stations. Return signals are transmitted by sections. The transmission channel available in the remote control network is divided into a wideband channel for the main transmission direction, and a narrow band channel for the opposite direction. Normally the wideband channel is used in the top to bottom direction, and the narrow band channel in the bottom to top direction.