Forums

Generator polynomial for reed solomon codes

Started by Sudeep April 22, 2004
Can anyone tell me which generator polynomial to use for rs(255,223) code

and also how to find out generator polynomila for other rs codes...(n,k)
                 sudeep
sudeepkumarts@hotmail.com (Sudeep) wrote in message news:<8dbc777c.0404212307.1b701aac@posting.google.com>...
> Can anyone tell me which generator polynomial to use for rs(255,223) code > > and also how to find out generator polynomila for other rs codes...(n,k) > sudeep
Use rspoly(n,k) [or rsgenpoly(n,k) in new Matlab versions] to get the generator polynomial for any RS(n,k) code. You can also specify the Primitive Polynomial if you like to. Rider
sudeepkumarts@hotmail.com (Sudeep) wrote in message news:<8dbc777c.0404212307.1b701aac@posting.google.com>...
> Can anyone tell me which generator polynomial to use for rs(255,223) code > > and also how to find out generator polynomila for other rs codes...(n,k) > sudeep
Hi, a Reed-Solomon Code is a code where the generator polynomail consists of h = n - k , i.e. h = (255-223) = 32, consecutive roots of a primitive element of the GF(2^m) field. Thus, for a (255,223) RS code you would use GF(2^8). The Galois Field polynomial in GF(2^8) with primitive element z will be a RS generator: g(x) = (1 - z^1)(1 - z^2)..(1 - z^32). Actually, the more general form would be g(x) = (1 - z^{i+1})(1 - z^{i+2})..(1-z^{i+32}). An RS code is also a cyclic code, implicating that g(x) should divide x^n - 1, or in the case above, x^255 - 1. Hope this helps a bit Jaco Versfeld