| 摘要 |
In accordance with one embodiment, a computer program product includes a computer readable storage medium having computer readable program code that is readable and/or executable by a processor to: receive a signal including precoded data read from a magnetic tape medium and pass the signal through a soft detector to calculate first soft information about each bit of the signal and to provide adaptive compensation for the precoded data, send the first soft information to a soft decoder, pass the signal through the soft decoder to calculate second soft information about each bit of the signal, and send the second soft information to the soft detector, wherein the precoded data is passed through at least one precoder prior to being written to the magnetic tape medium via a precoder that applies 1/(1⊕D2) to bits of data, where D is delay corresponding to bit duration. |
| 主权项 |
1. A data storage system, comprising:
a soft detector configured to calculate first soft information about each bit of a signal comprising precoded data read from a magnetic tape medium via a tape channel, and send the first soft information to a soft decoder, wherein the precoded data comprises a characteristic of being passed through at least one precoder prior to being written to the magnetic tape medium, wherein the soft detector provides automatic compensation for the preceded data, wherein the soft detector applies a Dual-Max (DMAX) algorithm comprising:αk(Sk)≅maxSk-1{γk(Sk-1,Sk)+αk-1(Sk-1)}βk-1(Sk-1)≅maxSk{γk(Sk-1,Sk)+βk(Sk)}LLR(αk)≅maxSk-1->Skak=+1{αk-1(Sk-1)+γk(Sk-1,Sk)+βk(Sk)}-maxSk-1->Skak=-1{αk-1(Sk-1)+γk(Sk-1,Sk)+βk(Sk)}, wherein yk is the signal, αk denotes a bit in a bit sequence of the signal, αk(Sk) is an alpha term for a current state (Sk) in a forward recursion, αk(Sk−1) is an alpha term for a previous state (Sk−1) in the forward recursion βk(Sk) is a beta term for the current state in a backward recursion, βk−1(Sk−1) is a beta term for the previous state in the backward recursion, and LLR(αk) is an approximation of a log-likelihood term that calculates a posteriori probabilities. |
