SPECTRAL PROPERTIES OF (D,K)-CODES WITH MULTIPLE SPACING

The multiple spaced (d, k) codes seem to have some application value f or magnetic recording and magneto-optic recording systems. Recently it was shown that these codes have a performance advantage when a partia l-response channel is considered, In this paper we will show that the multiple spaced (d, k) constraint has some interesting spectral proper ties. Certain choices of d and the spacing parameter will result in sp ectral nulls in the power spectrum. From these results it is shown tha t the previous choices of d and the spacing parameter are not optimal in terms of matching the spectral null of the sequence and that of the partial-response channel.