Dynamic information storage or retrieval – Binary pulse train information signal – Binary signal gain processing
Patent
1996-10-02
1997-10-21
Edun, Muhammad N.
Dynamic information storage or retrieval
Binary pulse train information signal
Binary signal gain processing
369 47, 369124, 360 46, G11B 700
Patent
active
056803834
ABSTRACT:
In a pulse width modulated read signal channel for an optical disk drive, a data-transition threshold is maintained for data detection by a threshold tracking circuit that estimates the amplitude centerline data-transition threshold from the most recent maximum and minimum values of the read signal waveform. To improve the accuracy of the response of the centerline estimator, the threshold is increased or decreased based on the phase error at each read signal transition through the data-transition threshold. In addition, defects in the optical recording media are detected, and a defect present signal is used to inhibit the transition phase error input to the centerline estimator. This prevents the estimator from moving the threshold to an incorrect stable level. In addition, the defect present signal boosts the error feedback in the centerline estimator. The estimator then more quickly follows the read signal waveform. As a result, the estimator reacquires the centerline of the waveform after the read head moves past the defect without retriggering the defect detection circuit.
REFERENCES:
patent: 5341249 (1994-08-01), Abbott et al.
patent: 5442492 (1995-08-01), Cunningham et al.
Clark Alan Robert
Hutchins Robert Allen
Jaquette Glen Alan
Patapoutian Ara Sarkis
Sutardja Pantas
Edun Muhammad N.
International Business Machines - Corporation
Knearl Homer L.
Sirr Francis A.
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