Dynamic magnetic information storage or retrieval – General processing of a digital signal – Head amplifier circuit
Patent
1996-06-05
1998-07-28
Psitos, Aristotelis M.
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Head amplifier circuit
360 65, G11B 509, G11B 5035
Patent
active
057869510
ABSTRACT:
This invention provides apparatus and a method to assist in calibrating a read channel in a magnetic data storage system. More particularly, the invention provides a read channel including a digital noise generator. During a calibration procedure, the digital noise generator injects an analog noise signal into the read channel, thereby increasing the read channel's bit-error rate, and consequently allowing rapid calibration of the read channel. The digital noise generator comprises a number of linear feedback shift registers that together generate a pseudo-random digital word sequence, and a digital-to-analog converter that converts the pseudo-random digital word sequence into the analog noise signal. The digital-to-analog converter comprises a plurality of one-bit digital-to-analog converters whose outputs are summed by an analog adder. This configuration causes the analog noise signal to exhibit a binomial probability distribution which is close to a normal probability distribution for a sufficiently large number of linear feedback shift registers. The linear feedback shift registers are driven by a clock that operates at a higher frequency than the rate at which data is processed in the read channel. The analog noise signal, therefore, has bandwidth that is wider than that of the data, thereby insuring that calibration of the read channel includes effects due to aliasing. The digital noise generator is disabled while the read head passes over synchronization marks and embedded servo wedges.
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Behrens Richard T.
Mehr Iuri
Welland David R.
Cirrus Logic Inc.
Neal Regina Y.
Psitos Aristotelis M.
Sheerin Howard H.
Shifrin Dan A.
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