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Media Noise Reduction in Disk Memory Devices

IP.com Disclosure Number: IPCOM000039107D
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Chen, M: AUTHOR [+2]

Abstract

Noise observed in the readout signal when recovering data from disk memory devices can originate from the media as well as from detection electronics. Media noise may be observed even on erased media. On the best phase-change optical disks, media noise is the dominant noise source, while on many magneto-optic disks, media noise is a significant part of the total noise. The data rate for disk memory devices is primarily determined by the disk noise in conjunction with the recorded signal strength, the sophistication of the data recovery electronics and the requirements of acceptable error rate. A method for reducing the effect of media noise in disk memory devices, particularly optical disk memory devices, is proposed. Such noise is often time-invariant, i.e.

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Media Noise Reduction in Disk Memory Devices

Noise observed in the readout signal when recovering data from disk memory devices can originate from the media as well as from detection electronics. Media noise may be observed even on erased media. On the best phase- change optical disks, media noise is the dominant noise source, while on many magneto-optic disks, media noise is a significant part of the total noise. The data rate for disk memory devices is primarily determined by the disk noise in conjunction with the recorded signal strength, the sophistication of the data recovery electronics and the requirements of acceptable error rate. A method for reducing the effect of media noise in disk memory devices, particularly optical disk memory devices, is proposed. Such noise is often time-invariant, i.e., the readout signal is reproducible upon successive readouts of the same segment of the disk. In the proposed method, the disk is read before data is written and writing conditions are adjusted to compensate for time-invariant media noise so that readout noise is effectively reduced. Referring to the figure, Write Compensation Electronics derives a compensation signal from the signal produced by a Read Detector. The compensation signal is produced during the disk revolution prior to writing or, as shown, by a separate read beam which leads the write basic spot on the disk. The compensation signal is combined with the data signal to adjust the writing power inverse...