Dynamic magnetic information storage or retrieval – General recording or reproducing – Specifics of equalizing
Reexamination Certificate
2008-04-15
2008-04-15
Nguyen, Hoa T. (Department: 2627)
Dynamic magnetic information storage or retrieval
General recording or reproducing
Specifics of equalizing
C360S051000, C360S039000
Reexamination Certificate
active
11733934
ABSTRACT:
A read channel equalizer of a magnetic tape drive which equalizes digitally sampled magnetic signals detected by a read head is dynamically adapted. A detector of equalizer dynamic adaptation logic compares equalizer output signals to desired values that are based on the decoding scheme (such as +2, 0 and −2 for PR4) to sense equalizer output signals that are offset from at least one desired value, and signals the fact of each offset and it polarity as amplitude independent error signals. The signaled sensed amplitude independent error signals are fed back to adjustable taps of the equalizer. The simplified error signals thus avoid complex calculations of waveform errors, such as least mean square calculations. The error signals may be weighted and may be adjusted to align synchronously provided error signals with asynchronous taps of the equalizer.
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Shahid U. H. Qureshi, Adaptive Equalization, Proceedings of the IEEE, vol. 73, No. 9, Sep. 1985, pp. 1349-1387.
Eleftheriou Evangelos S.
Hutchins Robert Allen
Jaquette Glen Alan
Oelcer Sedat
Holcombe John H.
Mercedes Dismery
Nguyen Hoa T.
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