A generalized scheme for generating and detecting recording channel output waveforms with controlled pulse polarity

In ordinary NRZI modulation, the recording channel output waveform consists of a pulse (i.e., the channel step response) for each NRZI 1, and no pulse for each NRZI 0, where the pulses always alternate in polarity. In previous work a modulation scheme was discussed whereby output waveforms with controlled pulse polarity were created. The result was a larger detection window than would have been possible for ordinary (d, k) modulation with d>0. The authors present a generalization of this modulation scheme. They discuss the run-length constraint required and show what density gains are possible. They introduce an enhanced peak detection scheme which helps to combat the baseline wander present in the output waveform. The enhanced detector is compared to a standard peak detector by computer simulation