Modulation Codes for Storage Systems

This chapter provides an introduction to the theory and practice of modulation coding for data storage channels. First, modulation codes are motivated as codes which can improve channel performance. Then basic properties of constraints, capacity, and codes are described, and some code construction methods are surveyed very briefly. Next, distance-enhancing codes and codes for colored noise and offtrack interference are developed. Finally, there are discussions of two topics of very recent interest: soft output decoding of modulation codes and the interplay between modulation codes and error-correction codes. The chapter includes many references to the literature, including more detailed and self-contained expositions of the subject.