Updated: Sep 18, 2020
✔️✏️📘A satellite data unit (SDU) is an avionics device installed in an aircraft that allows air/ground communication with a satellite network.
✔️✏️📘It is an integral part of an aircraft's SATCOM (satellite communications).
✔️✏️📘The device connects with a satellite with radio frequency (RF) communication and the satellite then connects to a ground station.
✔️✏️📘It maintains an update of ground stations in the aircraft's current area and the order of preference for selection of which ground station to use which thus guides the choice of satellite.
✔️✏️📘It is also used to offer Internet services to passengers in flight.
✔️✏️📘The SATCOM system uses aircraft supplied navigational position data to electronically or mechanically steer the antenna so it can orient itself toward the satellite in use.
✔️✏️📘As the aircraft moves out of the optimum communication position with one satellite, the SATCOM automatically switches to the next best satellite