Irreducible components of canonical diagrams for spectral nulls

A Barker sequence is a finite sequence a_o, ..., a_n-1, each term ±1, for which every sum Σ_ia_ia_i+k with 0 < k < n is either 0, 1, or -- 1. It is widely conjectured that no Barker sequences of length n > 13 exist, and this conjecture has been verified for ...

After several remarks on two-weight irreducible cyclic codes, we introduce a family of projective two-weight cyclic codes and a family of projective two-weight constacyclic codes and we discuss the existence of such codes.

In this paper, several families of irreducible constacyclic codes over finite fields and their duals are studied. The weight distributions of these irreducible constacyclic codes and the parameters of their duals are settled. Several families of ...$\mathrm{}\mathrm{}\mathrm{}\mathrm{}\sqrt{}\mathrm{}$$$$\mathrm{}\mathrm{}\mathrm{}\mathrm{}\sqrt{}\mathrm{}$$$${}_{\mathrm{}}\mathrm{}\mathrm{}$${}_{\mathrm{}}\mathrm{}\mathrm{}$