Editing Transponder (section)

==Satellite/broadcast communications==
{{See also|Transponder (satellite communications)}}
A [[communications satellite]]’s [[Communication channel|channels]] are called transponders because each is a separate [[transceiver]] or [[repeater]]. With [[digital video]] [[data compression]] and [[multiplexing]], several [[video]] and [[sound reproduction|audio]] channels may travel through a single transponder on a single [[wideband]] [[carrier signal|carrier]]. Original [[analog video]] only has one channel per transponder, with [[subcarrier]]s for audio and automatic transmission identification service ([[Automatic Transmitter Identification System (television)|ATIS]]). Non-multiplexed [[radio station]]s can also travel in [[single channel per carrier]] (SCPC) mode, with multiple carriers (analog or digital) per transponder. This allows each station to transmit directly to the satellite, rather than paying for a whole transponder, or using [[landline]]s to send it to an [[Earth station (communications)|earth station]] for multiplexing with other stations.