Some lower bounds on the minimum weight of cyclic codes of composite length

An extension of Goethals' results [3] is presented. Cyclic codes of composite block length
n = n_{1}n_{2}
with
n_{1}
and
n_{2}
relatively prime are considered. By using a modified form of the Mattson-Solomon formulation [5], some lower bounds on the minimum weight are obtained. These lower bounds improve on the BCH bound [4] for a considerable number of nonprimitive BCH codes.