Dynamic magnetic information storage or retrieval – General processing of a digital signal – Head amplifier circuit
Patent
1996-08-02
1998-06-30
Psitos, Aristotelis M.
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Head amplifier circuit
375290, 375340, G11B 509
Patent
active
057742863
ABSTRACT:
In a magnetic disk drive for writing write data by a head to a magnetic disk, equalizing a reproduced signal read out from the magnetic disk by a head at the time of reproduction, and effecting maximum likelihood detection for the reproduced signal after equalization and thus demodulating the read data, "1s" are periodically inserted as dummy bits into a data string of the write data. On the other hand, a timing signal and a clock signal which are synchronous with the positions of the dummy bits are generated from the reproduced signals after equalization, and a threshold level of binary/ternary judgement is switched by this timing signal. Binary judgement is made at the position of the dummy bit in the reproduced signal after equalization and path merge is unconditionally regarded as existing at the position of the dummy bit in the reproduced signal after equalization, and path retrieval is made, while ternary judgement is made for other code strings to execute maximum likelihood detection. As a result, in a magnetic disk drive for demodulating the read data by the maximum likelihood detection method, error propagation can be reduced, the encoding gain can be improved and a high speed maximum likelihood detection can be accomplished.
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patent: 4504872 (1985-03-01), Petersen
patent: 4918446 (1990-04-01), Yagi
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Fujitsu Limited
Psitos Aristotelis M.
Wamsley Patrick
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