Pseudo-ternary run-length limited spectrum shaped codes

A method to convert binary to pseudo-ternary sequences is proposed. The method keeps run-length constraints imposed on finite-length binary sequence and also provides a unit value of a channel transition. The resulting finite-length pseudo-ternary sequence has exponential sums falling within specified regions. This allows spectrum shaping. The average power spectral density of infinite sequences obtained by concatenating spectrally-constrained sequences is examined. Thus we obtain the pseudo-ternary spectrum shaped code, which generally yields higher capacity than the binary one.