Editing Single channel per carrier (section)

{{short description|Dedicated use of satellite bandwidth}}
{{Unreferenced|date=December 2009}}
{{For|the [[Sickle-cell disease]] symptom sometimes referred to as "SCPC"|Vaso-occlusive crisis}}

'''Single channel per carrier''' ('''SCPC''') refers to using a single [[signal]] at a given [[frequency]] and [[Bandwidth (signal processing)|bandwidth]].  Most often, this is used on [[broadcast satellite]]s to indicate that [[radio station]]s are not [[multiplexing|multiplexed]] as [[subcarrier]]s onto a single [[video]] [[carrier wave|carrier]], but instead independently share a [[transponder]]. It may also be used on other [[communications satellite]]s, or occasionally on non-satellite [[transmission (telecommunications)|transmission]]s.

In an SCPC system, satellite bandwidth is dedicated to a single source. This makes sense if it is being used for something like [[satellite radio]], which [[Broadcasting|broadcast]]s continuously. Another very common application is voice, where a small amount of fixed bandwidth is required.  However, it does not make sense for [[burst transmission]]s like [[satellite internet]] access or [[telemetry]], since a customer would have to pay for the satellite bandwidth even when they were not using it.

Where multiple access is concerned, SCPC is essentially [[Frequency-division multiple access|FDMA]]. Some applications use SCPC instead of [[Time-division multiple access|TDMA]], because they require guaranteed, unrestricted bandwidth. As satellite TDMA technology improves however, the applications for SCPC are becoming more limited.