Extended properties of high-order spectral-null words
Y. Xin, I.J. Fair · 2003
High-order spectral-null codes have found practical applications in systems with high-order partial response channels. We derive a necessary and sufficient condition on word length N of Mth-order spectral-null code words, denoted dc/sup M/ words. A new lower bound on the redundancy of dc/sup M/ words is also presented. Furthermore, we investigate truncations of the Morse sequence and prove that these truncations must represent two dc/sup M/ words with the shortest word length. We show that the power spectra of these short dc/sup M/ words (M/spl ges/2) have nulls at rational frequencies of the symbol frequency, and we derive the orders of these spectral nulls.