Dynamic information storage or retrieval – Binary pulse train information signal – Binary signal gain processing
Patent
1996-12-20
1999-10-05
Edun, Muhammed N.
Dynamic information storage or retrieval
Binary pulse train information signal
Binary signal gain processing
369 48, 369 97, G11B 700
Patent
active
059635258
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a process for reading a record carrier as well as to a device applying such a process.
The invention applies especially to the reading of magnetic or optical recordings and, more particularly, to the reading of high-density recordings. It finds a preferential application in recording systems such as computer peripherals and all business systems.
2. Discussion of the Background
In a digital recorder, the decoding of the binary information involves regenerating the time reference signal, referred to as the clock signal, which served in the recording of the information. This clock signal is usually produced by a voltage controlled oscillator (VCO) inserted into a phase locked loop (PLL) which is synchronized with the transitions of the reading signal.
In a multi-track recorder, it is possible to use a single clock signal reconstructed for the tracks as a whole, on condition that the synchronization between all the tracks written on the tape is preserved.
This presupposes that the recording heads and reading heads are aligned, and that the tape does not deform. If these conditions are not strictly complied with, the time references of the various tracks become offset one with respect to another, this being the slippage phenomenon known to those skilled in the art as "skew".
In the case in which the binary information is contained on a large number of parallel tracks, for example in the case in which the pitch between parallel tracks is of the order of 10 to 20 .mu.m, it is virtually impossible to maintain this slippage phenomenon within acceptable limits. It is then known to produce an independent clock regeneration circuit for each track. This has numerous drawbacks including, in particular, that of having to produce a large number of circuits.
SUMMARY OF THE INVENTION
The invention does not have these drawbacks.
The subject of the present invention is a process for reading binary information written on a carrier and constituting at least one track, the said binary information having been written onto the carrier at the frequency Fbit, characterized in that it comprises: so as to constitute a succession of successive read samples SAM(k) of the same track, k being the index of the read sample SAM(k), each read sample SAM(k) having its phase .phi.(k) lying between 0 and 2.pi., sample I(k) with phase equal to .pi. corresponding to the read sample SAM(k), on the basis of the read sample SAM(k) and of the i+j read samples (SAM(k-i), . . . , SAM(k+j)) which bracket the read sample SAM(k) such that: SAM.sub.(k+j), values chosen in accordance with the law of interpolation, intended to validate or to invalidate the interpolated sample I(k).
The subject of the present invention is also a system for reading binary information written on a magnetic carrier and constituting at least one track, the said binary information having been written onto the carrier at the frequency Fbit, comprising: luminous information the binary information read simultaneously on at least one track at the sampling frequency F.sub.e, information and making it possible to transform the said luminous information into a succession of voltage samples, the said photosensitive device comprising at least one output evacuating the said voltage samples, rearrange the gathered voltage samples on the said output in such a way as to obtain a succession of successive read samples SAM(k) of the same track, k being the index of the sample SAM(k) on the track, means of interpolation making it possible to calculate an interpolated sample I(k) for each read sample SAM(k) on the basis of the sample SAM(k) and of the i+j read samples which bracket the sample SAM(k) in such a way that: values dependent on the law of interpolation chosen, and means of validation making it possible to generate an information item (VAL) intended to validate or to invalidate the interpolated sample I(k).
An advantage of the invention is that it avoids multiplication of the clock regeneration circuits and
REFERENCES:
patent: 4815067 (1989-03-01), Webster et al.
patent: 5566155 (1996-10-01), Hayashi
patent: 5586100 (1996-12-01), Lee et al.
patent: 5602811 (1997-02-01), Ogusu et al.
patent: 5615198 (1997-03-01), Kubokawa
patent: 5633851 (1997-05-01), Kahlman et al.
Audoin Michel
Colineau Joseph
De Vito Mario
Hanna Charaf
"Thomson-CSF"
Edun Muhammed N.
Thomson Multimedia
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