Channel coding for binary recording with intersymbol interference

The saturation recording channel with fixed-amplitude bipolar inputs, a linear Lorentzian read-back transition response, and additive Gaussian noise is modeled. Linear density increase on such a channel can be achieved only by increasing the clock rate of the written data signal. The authors define a measure of coding gain for the recording channel that compares a coded system with an uncoded system, each at a different clock rate, but with the same linear density (or data rate). This measure can be decomposed into the sum of an equalization gain and a fundamental coding gain. It is shown that good equalization gain can be achieved by choosing multidimensional codewords such that their power spectra are `matched´ to the channel pulse response spectrum, and they have increased minimum distance at the channel output