Downlink
The radio frequency transmission path from a satellite to an earth station or user terminal. Contrasted with uplink, which is the ground-to-space path.
Full Definition
The downlink is the signal path from the satellite's transmit antenna to the receiving earth station or user terminal. Downlink frequencies are assigned below uplink frequencies within the same band pair to take advantage of the lower noise environment at ground receivers relative to satellite receivers. In document editing, 'downlink' is always one word, and its direction (space-to-ground) should be carefully distinguished from 'uplink'. The term is used as a noun ('the downlink was strong'), a verb ('the spacecraft downlinked telemetry'), and an attributive adjective ('downlink frequency', 'downlink margin'). Confusing the direction of uplink and downlink is a critical editorial error in technical satellite documents.
Usage
Usage note: Always one word: 'downlink'. In VSAT hub-spoke terminology, 'return link' (remote-to-hub direction) is a distinct concept; do not use interchangeably with 'downlink'.
In Context
- "The broadcast downlink at 12.5 GHz was receivable with a 60 cm dish across the entire European footprint." — Coverage Analysis Report
- "Spacecraft engineers confirmed the downlink telemetry stream was nominal following the orbit-raising manoeuvre." — Mission Status Report