Abstract: The radio station comprises a receiver antenna system responsive to direct transmissions from each of the other radio stations in the system with two remote transmitters operated alternately, i.e. one can be moved while the other is transmitting. The antennae system provides input signals to a receiver bank, each receiver being responsive to the current transmission frequency of a respective one of the other radio stations in the system. The received signals, comprising packets of data addressed to a particular station, are processed in decrypt section and switch section, then the data packets are either passed to a database, one of the workstations or rejected, depending on the addressee of each packet. Data from the database or any of the workstations for transmission to specified addresses are processed and stored in the switch section ready to be transmitted from one of the two remote transmitters during one or more subsequent transmission periods.