The Space Communications Protocol Specifications (SCPS) are a set of extensions to existing protocols and new protocols developed by the Consultative Committee for Space Data Systems (CCSDS) to improve performance of Internet protocols in space environments. The SCPS protocol stack consists of:

  • SCPS-FP—A set of extensions to FTP to make it more bit efficient and to add advanced features such as record update within a file and integrity checking on file transfers
  • SCPS-TP—A set of TCP options and sender-side modifications to improve TCP performance in stressed environments including long delays, high bit error rates, and significant asymmetries. The SCPS-TP options are TCP options registered with the Internet Assigned Numbers Authority (IANA) and hence SCPS-TP is compatible with other well-behaved TCP implementations.
  • SCPS-SP—A security protocol comparable to IPsec
  • SCPS-NP—A bit-efficient network protocol analogous to, but not interoperable with, IP

The SCPS protocol that has seen the most use commercially is SCPS-TP, usually deployed as a Performance Enhancing Proxy (PEP) to improve TCP performance over satellite links.

The SCPS protocols are part of a broader ecosystem of space communication protocols. Beyond SCPS, satellite communications use various protocols depending on the mission type:

Protocol decoding

Reverse engineering and decoding satellite communications involves several steps:

  • Protocol documentation: documenting the protocol structure for future automated decoding.

Common tools for protocol decoding include GNU Radio, GQRX, SatDump, and gr-satellites.

See also

External links

  • is a web page devoted to the SCPS protocols and contains links to the protocol specifications, briefing material, and test results.[dead link] (at theWayback Machine(archive index))
  • The distributes a free reference implementation of the SCPS protocols that includes a transport-layer PEP application.
  • is the main web page for the CCSDS.