Patent ID: 6914948

Claim:
A post-processing method for correcting media noise errors and producing a recovered data output signal, for use in a sampled data read channel of a mass data storage device that has a Viterbi detector that receives actual sampled partial response target data from a data medium of the mass data storage device, comprising: filtering a recovered partial response target signal derived from said recovered data output signal and said sampled partial response target data to produce a filtered output signal; providing a threshold circuit to provide a threshold against which said filtered output signal is compared; adding a predetermined value to the filtered output signal when a predetermined error event pattern due to media noise occurs in said recovered data output signal; and modifying the recovered data output signal when said filtered output signal exceeds the threshold of said threshold circuit, wherein said predetermined value in an EEPR4 channel is determined from the following tables: Recovered Write Current ĉ(k) k −3 −2 −1 0 1 2 3 Output X 0 0 X 0 0 X Ajitter 1 1 0 X 0 0 X X 0 0 X 0 1 1 X 1 1 X 1 1 X −Ajitter 0 0 1 X 1 1 X X 1 1 X 1 0 0 Others 0 Polarity Check Correction Amplitude Polarity ĉ(0) ĉ(1) ĉ(0) ĉ(1) *fexA(6) *>VthA FexA(6) > 0 0 X 1 X FexA(6) < 0 1 X 0 X *FexB(6) *>VthA FexA(6) > 0 0 1 1 0 FexA(6) < 0 1 0 0 1 wherein the polarity check correction table is logically or'd with the output of the recovered write current ĉ(k) table to produce a correction value where x is either 1 or 0.