Dan Halperin wrote: > Standards for access codes are interesting. The Barker spreading code > use in 802.11 1 and 2Mbps rates, for instance, is one of a set of > optimal codes where B (dot) B = |B| while > B (dot) (B rotated by any nonzero number of bits) = 1. This means that > if you're sliding a correlator along a set of Barker-modulated bits, you > get strong peaks at the correct offset and (basically) nothing at any > other offset.
In addition to the auto-correlation properties described above, there may be a requirement for a set of multiple access codes to have negligible cross-correlation with other members of the set. Some protocols use multiple access codes (also known as sync codes) to signal the type of frame that follows (e.g., the FLEX pager protocol, see pageri_flex_codes.cc in the tree). -- Johnathan Corgan Corgan Enterprises LLC http://corganenterprises.com _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
