These communication systems include public address systems, interior telephone systems, alarm systems, engine telegraphs to communicate orders for changes in engine speed from the bridge (ship's command station) to the engine room, certain kinds of ship control and equipment monitoring devices, the ship's gyrocompass, the rudder position indicator, audio-visual equipment for the ship's TV entertainment systems, advanced navigation and various other equipment.
These communication systems on board include public address systems, interior phone networks, alarm systems, engine telegraphy for transmitting orders from the bridge to the engine room, various control and monitoring devices, the ship's gyrocompass, rudder position indicators, entertainment audio-visual gear, navigation aids, and other critical equipment.