Thomson Licensing

Thomson Licensing S.a.

Deutsche Thomson-brandt Gmbh

Marten Kabutz

Alexander Kravtchenko

Bruno Peytavin

Christian Büchler

Stefan Müller

Axel Kochale

Klaus Gaedke

Richard Rutschmann

Friedrich Timmermann

Xavier Lebegue

Herbert Schütze

Lothar Freissmann

Ralf-Detlef Schaefer

Qilong Feng

A method is provided for receiving and restoring data from an optical recording medium exhibiting strong asymmetry in the regenerated RF signal. The method provides digital partial response asymmetry compensation of a digital RF signal. The asymmetry of the digital RF signal is detected through the measurement of the envelopes of a short T pulse (xT pulse) and a long T pulse (yT pulse), where the T is the bit clock of the recovered bit stream. Through the evaluation of the xT upper and lower envelopes and the asymmetry factor, upper and lower thresholds are determined. Only the asymmetric parts of the digital RF signal are selected and compensated.

Digital partial response asymmetry compensation

A bit clock recovery apparatus for digital storage readout employing sync frames, where an oversampled readout signal is stored in memory, sync patterns are located in the signal using DSP means, distances of consecutive sync pattern locations are calculated, and bit clock is recovered from these distances and the knowledge about the data framing structure.

DSP-based data recovery

A method and apparatus for error correction of an encoded data stream. A demodulated data stream is saved in an input buffer. A first correction process is performed on-the-fly in the input buffer. The data is transferred to an external SDRAM after correction. A data frame is copied from the external SDRAM to an embedded SRAM. A multipass correction is started in the embedded SRAM. The corrected data frame is copied back from the embedded SRAM to the external SDRAM.

Error correction method for reed-solomon product code

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

The invention relates to a Reed-Solomon decoder and to a method of soft decision decoding of Reed-Solomon codes, wherein a syndrome polynomial, an erasure polynomial, and a modified syndrome polynomial are computed on-the-fly in parallel by iteratively updating coefficients of these polynomials.

Method of soft-decision decoding of Reed-Solomon codes

A method for determining the address of a frame inside a data sector of an optical recording medium (), the sector comprising a plurality of frames, each frame being preceded by a synchronization code, and an apparatus () for reading from and/or writing to optical recording media () using such method. A method for determining the address of a frame inside a data sector of an optical recording medium () that is robust against streaming loss is proposed. The method comprises the steps of:

Method for in-sector data management in frame addressing

A method and arrangement for using Synchronous Dynamic Random Access Memory (SDRAM) as storage for correction and track buffering in front end ICs of optical recording or reproduction devices. Data to be stored or read is organized in appropriate bursts for accelerating the SDRAM (SDR) traffic. The SDRAM is built around two banks of memory, and are accessed using a pipelined address logic, thereby accelerating access speeds.

Usage of an SDRAM as storage for correction and track buffering in frontend ICs of optical recording or reproduction devices

An apparatus for reading from or writing to optical recording media, having a photodetector and a phase detector for detecting a phase difference between output signals of the photodetector. An object of the present invention is to propose an apparatus in which a phase signal which is as correct as possible is generated. A further object of the invention is to specify a method of which a correct track error signal is determined using a phase detection method. According to the invention, the apparatus has an edge sequence detector for detecting the sequence of edges of the output signals, and a signal blocking unit for blocking the output signal of the phase detector. In particular, the output signal of the phase detector is blocked when an impermissible sequence of zero crossings of phase detected signals.

Apparatus for scanning optical recording media using a differential phase detection method

Method for tracking in an apparatus for reading from and/or writing to an optical recording medium, and corresponding apparatus for reading from and/or writing to an optical recording medium. In order, in an apparatus for reading from and/or writing to an optical recording medium (), to enable exact counting of the tracks of the optical recording medium () crossed by an optical scanning unit (), it is proposed to derive a signal corresponding to the TZC signal (Tracking ZeroCross) and also a signal corresponding to the MZC signal (Mirror Zero Cross) from the output signal or the output signals (OUT1, OUT2) of a phase comparator () provided for tracking in accordance with the so-called differential phase detection method.

Method for tracking in an optical recording/reading apparatus, and corresponding apparatus

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.

Growing community of inventors

Villingen-Schwenningen, Germany

Marten Kabutz