Channel coding for digital recording

Finding a digital code that maximizes the net linear density while maintaining satisfactory data reliability is a frequent objective in designing a channel for digital magnetic recording. This tutorial paper summarizes analog channel characteristics significant to the modulation and error-correction codes. Selection parameters for a modulation code are also discussed. Three statistical distributions are considered that describe the observable effects of the underlying probability of error. These distributions form the basis for selecting the error-correction code. Consideration is also given to the impact of system constraints on the selection of digital codes.