Transponder
A satellite payload channel that receives an uplink signal, frequency-converts it, amplifies it, and retransmits it as a downlink signal. Transponders are the fundamental bandwidth unit leased by satellite operators.
Full Definition
A satellite transponder is an electronic package aboard a communications satellite that performs the receive-translate-retransmit function for a defined portion of radio frequency spectrum. Conventional transponders are 'bent-pipe', meaning they translate frequency and amplify without processing signal content. Transponder bandwidth is typically 36 MHz for Ku-band and 54 MHz for C-band, though this varies. Satellite capacity is bought and sold in units of transponder bandwidth or MHz equivalents. Editors should not confuse 'transponder' with 'repeater', nor with TT&C transponders aboard the satellite, which serve a different function. The term is one word, never hyphenated.
Usage
Usage note: One word, no hyphen. When referring to leased capacity, specify bandwidth: 'a 36 MHz transponder at Ku-band'. Distinguish from TT&C transponders, which handle housekeeping signals rather than payload traffic.
In Context
- "The broadcaster leased one full 36 MHz transponder on the geostationary satellite for its direct-to-home bouquet." — Capacity Lease Agreement
- "Editors should verify that 'transponder' and 'payload' are not used interchangeably in this technical specification." — Editorial Review Note