Comment by mijowi

I, too, was in the navy and supervised this very exercise on a ship. The exercise simulates a doomsday scenario that presumes satellite comms are out after a nuclear strike. Ships and other stations retransmit the messages over HF in order to eventually reach nuclear-armed subs for assured second strike capability. HF, with its semi-BLOS (beyond line of sight) range, is used to form a global communications network without satellites. The range of course depends on how much signal bounces off the atmosphere, which is why many stations are needed for redundancy. The whole exercise is Top Secret.