Thomson Licensing S.a.

Thomson Licensing

Deutsche Thomson-brandt Gmbh

Bruno Peytavin

Marten Kabutz

Alexander Kravtchenko

The present invention relates to a device for reading from and/or writing to optical recording media () having an optical scanner () for scanning the recording medium () by means of a light beam () and for generating scanning signals (HF) from the reflected beam (), a data slicer () for converting a scanning signal (HF) output by the optical scanner () into a binary signal (HF&#x2033;), an averaging unit () for forming an average value (M) from the scanning signal (HF, HF&#x2033;) as input signal of the data slicer (), and a control unit () for changing a parameter (T, OF) of the averaging unit (). The object of the present invention is to propose a device of this type and also a suitable method therefor in which the average value (M) can be adapted to disturbances during the scanning of the recording medium. According to the invention, this is achieved by virtue of the fact that the control unit () has a unit () for outputting a comparison value (S, HFN) and a comparator () for comparing the average value (M) with this comparison value (S, HFN), and triggers a chance in the parameter (T, OF) in the event of the comparison value exceeded or undershot.

Device for reading from or writing to optical recording media having a control unit for a data slicer

Disclosed is an apparatus for detecting a signal received from a channel signal and for transforming this signal into a binary code sequence via a signal processing apparatus, which can perform a maximum likelihood detection of the reproduced data from an optical disk with reduced complexity. Accordingly, a method to detect a signal (EBS) received from a channel signal (HF), comprises the steps of digitizing the signal received from the channel, equalizing the digitized signal (A ), generating branch metrics (b_mp, b_pm) from the equalized signal (B ), determining the minimum (b_ml) of the generated branch metrics (b_mp, b_pm), determining a merge (m&minus;, m&plus;, m ) from the minimum (b_ml), and generating a bitstream signal from the succession of merges (m&minus;, m&plus;, m

Method and apparatus to detect a signal received from a channel signal

DVDs have currently the highest storage density among the optical discs of practical use. Due to the high storage density the reproduced signal is deteriorated by noise caused by inter-symbol interference, crosstalk, focus error, or mastering errors. A conventional threshold bit detector generates a high bit error rate in case of low SNR. For accurate reproduction of digital data from a DVD under low SNR conditions, a specific Viterbi detector is used which performs maximum likelihood sequence estimation.

Method and apparatus for determining the value of samples received from bitstream data stored on a storage medium, and for recovering bits of said bitstream using a viterbi detector

The present invention relates to an apparatus for reading and/or writing data markings of an optical recording medium having data markings arranged along a track and header markings arranged laterally offset with respect to the center of this track. The apparatus has a signal conditioner, a header identification unit and a switch unit driven by the latter. The object of the invention is to enable data and header markings to be read out with the lowest possible error rate. For this purpose, the apparatus according to the invention has a threshold value forming unit and a storage unit with at least two storage locations, in which case, by means of the switching unit, the input of the storage unit can be connected to the output of the threshold value forming unit and the output of the said storage unit can be connected to a threshold value input of the signal conditioner. The apparatus according to the invention is suitable for reading from or writing to optical recording media such as a DVD-RAM, for example.

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Grenoble, France

Bruno Peytavin