Generation of spectral nulls with permutation sequences

This paper describes the construction of classes of spectral null codes, which are obtained by shaping permutation sequences. The properties and the construction techniques of binary spectral null codes are used. The power spectral densities (PSD) of the proposed codes show nulls at the zero frequency and at submultiples of the frequencies of the transmitted symbols. The channel symbols or voltage levels mapped to each transmitted permutation symbol are chosen to satisfy the spectral null equation. Interesting results show the elimination of the DC component at the lower frequencies. The well-shaped power spectral densities of these codes may overcome some communications problem like zero frequency components. The proposed technique is generalized and the corresponding spectral null permutation sequences that generate spectral null codes are presented.