Interleaved maximum likelihood decoding in high-order partial responses for high-speed magnetic recording systems

A high-order partial response (PR) that is generally represented by (1+D)(1-D/sup n/) and provides both high density and high speed in hard disk drive (HDD) signal processing is proposed. By using a pre-coding 1/(1+D), the n-bit interleaving operation for high-speed processing can be used. When n=3, the reduced equalization noise gain is about 4 dB higher than in the conventional PR4 at a channel density of 3.0, and the same squared Euclidean distance as with the PR4ML is attained in a 3-bit interleaving maximum likelihood detector. High-order PR channels for perpendicular recording are also proposed.