Uplink

In telecommunication, the term uplink (U/L) has the following meanings:

1. The portion of a communications link used for the transmission of signals from an Earth terminal to a satellite or to an airborne platform. An uplink is the converse of a downlink. An uplink or downlink is distinguished from reverse link or forward link.
2. Pertaining to data transmission from a data station to the headend.

Source: from Federal Standard 1037C in support of MIL-STD-188