An improvement on constructions of t-EC/AUED codes

A common method of constructing t-error correcting/all unidirectional error detecting (t-EC/AUED) codes is to choose a t-EC code and then to append a tail such that the new code can detect all unidirectional errors. The tail is a function of the weight of the codeword. We present a technique to reduce the weight distribution of the t-EC code so that the tail needed will be shorter in some cases. The weight distribution span of the code is reduced by eliminating the all-zero codeword and replacing it with a codeword of weight greater than 2t+1.