SCPC

Single Carrier Per Channel (SCPC) refers to using a single signal at a given frequency and bandwidth in a Satellite link. Contrasts with TDMA.

In a SCPC system, satellite bandwidth is dedicated to a single source. This makes sense if it is being used for something like satellite radio, which broadcasts continuously. But, it doesn't make sense for "bursty" transmissions like satellite internet access or Telemetry, since a customer would have to pay for the satellite bandwidth even when they weren't using it.

Some applications use SCPC instead of TDMA, because they require guaranteed, unrestricted bandwidth. As satellite TDMA technology improves, the applications are becoming rarer.

History

SCPC got its name from the older analog transmission technology, when a single satellite channel could carry only one data carrier.

Advantages

• Reliable, Simple Technology
• Low cost equipment
• Any Bandwidth (up to a full transponder)
  • usually 64 kb/s to 2 mb/s
• Easy to add additional receive sites

Disadvantages

• Inefficient use of satellite bandwidth for bursty transmissions
• Usually requires on-site control.
• When used in remote locations, the transmitting dish must be protected.
  • A dish which is moved out of alignment can result in fines as high as $1,100 per MINUTE (2003) from the satellite operator.

MCPC

Multiple Channels Per Carrier (MCPC) - several carriers are combined on a carrier transmitted from a single location to one or more remote sites. Usually uses Frequency-division multiplexing (FDM).