Editing Error detection and correction (section)

=== Deep-space telecommunications ===
The development of error-correction codes was tightly coupled with the history of deep-space missions due to the extreme dilution of signal power over interplanetary distances, and the limited power availability aboard space probes. Whereas early missions sent their data uncoded, starting in 1968, digital error correction was implemented in the form of (sub-optimally decoded) [[convolutional code]]s and [[Reed–Muller code]]s.<ref name="deep-space-codes">K. Andrews et al., ''The Development of Turbo and LDPC Codes for Deep-Space Applications'', Proceedings of the IEEE, Vol. 95, No. 11, Nov. 2007.</ref> The Reed–Muller code was well suited to the noise the spacecraft was subject to (approximately matching a [[Gaussian function|bell curve]]), and was implemented for the Mariner spacecraft and used on missions between 1969 and 1977.

The [[Voyager 1]] and [[Voyager 2]] missions, which started in 1977, were designed to deliver color imaging and scientific information from [[Jupiter]] and [[Saturn]].<ref name="voyager">{{cite book |first1=William Cary |last1=Huffman |first2=Vera S. |last2=Pless |author-link2=Vera Pless |title=Fundamentals of Error-Correcting Codes |publisher=[[Cambridge University Press]] |year=2003 |isbn=978-0-521-78280-7 |url-access=registration |url=https://archive.org/details/fundamentalsofer0000huff }}</ref> This resulted in increased coding requirements, and thus, the spacecraft were supported by (optimally [[Viterbi decoder|Viterbi-decoded]]) convolutional codes that could be [[concatenated code|concatenated]] with an outer [[Binary Golay code|Golay (24,12,8) code]]. The Voyager 2 craft additionally supported an implementation of a [[Reed–Solomon code]]. The concatenated Reed–Solomon–Viterbi (RSV) code allowed for very powerful error correction, and enabled the spacecraft's extended journey to [[Uranus]] and [[Neptune]]. After ECC system upgrades in 1989, both crafts used V2 RSV coding.

The [[Consultative Committee for Space Data Systems]] currently recommends usage of error correction codes with performance similar to the Voyager 2 RSV code as a minimum. Concatenated codes are increasingly falling out of favor with space missions, and are replaced by more powerful codes such as [[Turbo code]]s or [[LDPC code]]s.

The different kinds of deep space and orbital missions that are conducted suggest that trying to find a one-size-fits-all error correction system will be an ongoing problem. For missions close to Earth, the nature of the [[Noise (electronics)|noise]] in the [[communication channel]] is different from that which a spacecraft on an interplanetary mission experiences. Additionally, as a spacecraft increases its distance from Earth, the problem of correcting for noise becomes more difficult.