A new coding technique for spectral shaping of data

Spectrum shaping codes introduce redundancy and correlation into a transmitted data stream in order to alter the transmitted spectrum without affecting the pulse shape or peak-to-average power ratio. Most are based on algebraic properties, or on a running digital sum. A new and very general approach to spectral shaping, in which the Viterbi algorithm is used at the transmitter to minimize the transmitted power in specified bands, is introduced. The principal advantage is greatly increased flexibility of width, depth, and placement of spectral notches. The computational load at the transmitter is greater than that of earlier algorithms, although the receiver is unaffected