Gold code

A Gold code, also known as Gold sequence, is a type of binary sequence, used in telecommunication (CDMA)[1] and satellite navigation (GPS).[2] Gold codes are named after Robert Gold.[3][4] Gold codes have bounded small cross-correlations within a set, which is useful when multiple devices are broadcasting in the same frequency range. A set of Gold code sequences consists of 2n − 1 sequences each one with a period of 2n − 1.

A set of Gold codes can be generated with the following steps. Pick two maximum length sequences of the same length 2n − 1 such that their absolute cross-correlation is less than or equal to 2(n+2)/2, where n is the size of the LFSR used to generate the maximum length sequence (Gold '67). The set of the 2n − 1 exclusive-ors of the two sequences in their various phases (i.e. translated into all relative positions) is a set of Gold codes. The highest absolute cross-correlation in this set of codes is 2(n+2)/2 + 1 for even n and 2(n+1)/2 + 1 for odd n.

The exclusive or of two different Gold codes from the same set is another Gold code in some phase.

Within a set of Gold codes about half of the codes are balanced – the number of ones and zeros differs by only one.[5]

Gold codes are used in GPS. The GPS C/A ranging codes are Gold code of period 1,023.

See also

References

  1. ↑ George, M.; Hamid, M.; Miller, A. "Gold Code Generators in Virtex Devices" (PDF). Xilinx.com. Archived from the original (PDF) on July 5, 2008.
  2. ↑ "Transmitted GPS Signals". The GPS System. kowoma.de. Archived from the original on 2012-08-04.
  3. ↑ "Robert Gold, BS, MS, Ph.D." Robert Gold Comm Systems. 2011.
  4. ↑ Gold, R. (October 1967). "Optimal binary sequences for spread spectrum multiplexing (Corresp.)". IEEE Transactions on Information Theory. 13 (4): 619–621. doi:10.1109/TIT.1967.1054048.
  5. ↑ Holmes 2007, p. 100

Further reading

  • Holmes, Jack K. (30 June 2007). Spread Spectrum Systems for GNSS and Wireless Communications. GNSS Technology and Applications Series. 45. Artech House. ISBN 978-1-59693-083-4.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.