On-board data handling

The on-board data handling (OBDH) subsystem of a spacecraft is the subsystem which carries and stores data between the various electronics units and the ground segment, via the telemetry, tracking and command (TTC) subsystem.

In the earlier decades of the space industry, the OBDH function was usually considered a part of the TTC, particularly before computers became common on board. In recent years, the OBDH function has expanded, so much that it is generally considered a separate subsystem to the TTC, which is these days concerned solely with the RF link between the ground and the spacecraft.