Abstract:
We consider $q$-ary block codes with exactly two distances: $d$ and $d + 1$. Several constructions of such codes are given. In the linear case, we show that all codes can be obtained by a simple modification of linear equidistant codes. Upper bounds for the maximum cardinality of such codes are derived. Tables of lower and upper bounds for small $q$ and $n$ are presented.
Keywords:two-distance codes, equidistant codes, bounds for codes.