Distance enhancing constraints for noise predictive maximum likelihood detectors
Bruce E. Moision, Paul H. Siegel · 2002
Using performance analysis of reduced state sequence estimators (RSSE), we characterize dominant error events for a noise predictive maximum likelihood (NPML) detector in high density magnetic recording systems. The error event characterization may be used to determine distance enhancing constraints that improve the reliability of NPML/RSSE detection. An example of a constraint that provides approximately 0.8 dB asymptotic coding gain for an NPML detector operating at a user bit density of 2.54 is illustrated.