Abstract: This invention proposes synchronization patterns for RLL codes with a constraint. Instead of including the synchronization pattern in the pattern the pattern is chosen to have p leading bits and q trailing bits such that all channel code constraints are met by the last code word of the section preceding the synchronization pattern together with the p leading bits and by a first code word of the section following the synchronization pattern together with the q trailing bits of the synchronization pattern. This results in a freely insertable synchronization pattern that can be inserted after coding and removed before decoding resulting in an more efficient coder and decoder.

Abstract: Presently known codes have long trains consisting of consecutive 2T runs that reduce the performance of the bit detector. By using a code with an RMTR constraint of 2 an improvement in the bit detection is achieved. A code constructed in a systematic way that provides an RMTR constraint of 2 is presented. Several variations of such a code are disclosed where one or more sub-codes are used, where coding states are divided into coding classes ordered according to more or less stringent constraints on leading bits and where code words are divided into code word types ordered according to more or less stringent constraints on trailing bits. Then, for a given sub-code, an code word of type t can be concatenated with an code word of the next sub-code if said subsequent code word of said next sub-code belongs to one of coding states of the coding class with index Tmax+1?t.

Abstract: A method is disclosed for reading information from an optical disc (2) containing tracks (11, 21) with 2D-SCIPER coded information. The method comprises the steps of: generating at least one light beam (32); focussing the light beam (32) in a focal spot (F) on an information layer of the optical disc (2); controlling the radial position of the focal spot (F) such that the focal spot (F) covers pits (10; 20) of two adjacent tracks (11; 21). The optical centre (42) of the focal spot (F) follows a trajectory (45) which is radially offset with respect to a halfway line (44) at a position exactly halfway between the said two adjacent tracks (11; 21). According to this method, the disturbing non-linear intersymbol interference is removed from the multi-level eye-pattern of 2D-SCIPER, yielding much better distinguishable signal levels.

Abstract: A loss of performance of slicer adaptation at high capacities due to the mismatch between the exact bits used in the computation of the RDS for the DC-control on the one hand and the often erroneous threshold decisions that are preliminarily made based on the HF waveform on the other hand, is resolved by performing a new method of DC-control at the encoder: the RDS is modified such that it is not based on the exact channel bits, but on the threshold decisions from a synthetic HF signal waveform that is generated based on a nominal MTF (modulation transfer function) or its IRF (impulse response function) of the channel. In this way, the impact of the erroneous threshold decisions in the receiver are already taken into account at the encoder, and the slicer control is no longer negatively affected thereby.

Abstract: The present invention relates to a device in a corresponding method for encoding a secondary information (r) of a secondary channel into a channel data stream (3) of a primary channel, said channel data stream (3) comprising at least two symbol rows of channel symbols one-dimensionally evolving along a first direction (t) and aligned with each other along a second direction (r), said two directions constituting a two-dimensional lattice of symbol positions.

Abstract: The present invention relates to a method and apparatus for controlling at least one readout parameter of a magneto-optical domain expansion recording medium. An average detected runlength of the reading signal is monitored, and an error signal is generated on the basis of a comparison of the monitoring result with the predetermined average runlength that has been set during the encoding step. The at least one readout parameter is then controlled by means of the generated error signal. Furthermore, the present invention relates to a method, apparatus and record carrier wherein a runlength constraint is applied to at least one of the following quantities: mark regions and space regions in said storage layer, said runlength constraint being selected to keep an accumulated runlength deviation from a predetermined average runlength within a predetermined range.

Abstract: In modem optical disc systems, inter-track spacing is chosen relatively small in order to allow high storage densities. As a result, the optical spot has a radius comparable with the track pitch, and the data written on neighboring tracks appear in the target track signal in the form of inter-track interference (cross-talk). To tackle the cross-talk problem, cross-talk canceling schemes are normally employed. These schemes use three spots, one spot on the main track and two satellite spots on adjacent tracks. The read signal (C) is improved by minimizing the cross-talk between the satellite signals (S+,S?) and the read signal (C). However, due to the decreasing inter-track spacing, the decorrelation concept fails since the satellite spots read too much central track information and become strongly correlated with the read signal (C), which causes “leakage” in the decorrelation.

Abstract: The present invention relates to a symbol detection apparatus for detecting the symbol values of a two-dimensional channel data stream recorded on a record carrier, said channel data stream comprising a set of contiguous symbol strips (B) of symbol rows (r) onedimensionally evolving along a first direction and being aligned with each other along a second direction, said two directions constituting a two-dimensional lattice of symbol positions.

Abstract: A recording apparatus for recording channel symbols of a channel data stream on a record carrier (50), said apparatus being adapted for recording said channel symbols as a channel band (cb) of at least two symbol rows (sr) one-dimensionally evolving along a first direction (t) and aligned with each other along a second direction (r), said two directions constituting a two-dimensional lattice of symbol cells (sc) each being associated with a symbol area (sa) of the record carrier (50).

Abstract: When processing a two dimensional data area it is known to be advantageous to divide the two dimensional are into stripes and process each stripe using a stripe-wise detector. The stripe being processed shifts row per row downwards. Each stripe has as its output the bit-decisions of the top bit-row of the stripe which is the most reliable. That output bit-row is also used as side-information for the bit detection of the next stripe which is the stripe which is shifted one bit-row downwards. The bit-row just across the bottom of the stripe on the other hand still needs to be determined in the current iteration, so only the initialisation bit-values can be used in the first iteration of the stripe-wise bit-detector. In order to prevent the propagation of errors towards the top bit row of the stripe the relative weight for the bottom branch bit in the figure-of-merit is reduced from the full 100% to a lower fraction.

Abstract: The invention relates to a signal comprising a runlength limited (RLL) encoded binary d,k channel bitstream 3, wherein parameter d defines a minimum number and parameter k defines a maximum number of zeroes between any two ones of said bitstream 3 or vice versa, comprising a number of sections of respectively N successive RLL channel bits, called RLL rows 8-13, 45, each RLL row 8-13, 45 representing a parity-check code-word, called row parity-check code-word, in which a so-called row-based parity-check constraint for said RLL row 8-13, 45 has been realized, characterized in that K sections of respectively N successive channel bits, called column parity-check rows 21, 22, 43, 44, 46, are located at predetermined positions of a group of M RLL rows 8-13, 45, K, N and M being integer values, said column parity-check rows 21, 22, 43, 44, 46 comprising a plurality of column parity-check enabling channel words 30, 42, 48, wherein each of said column parity-check check enabling channel words 30, 42, 48 realizes a so-

Abstract: When processing a two dimensional data area it is known to be advantageous to divide the two dimensional are into stripes and process each stripe using a stripe-wise detector. When using several iterations it is advantageous to use higher complexity detectors in later iterations and lower complexity detectors in the initial iterations.

Abstract: The present invention relates to a method of determining write parameters for recording information on a record carrier, said information being in the form of a multidimensional channel data stream to be recorded as a channel band of at least two symbol rows one-dimensionally evolving along a first direction and aligned with each other along a second direction.

Abstract: The present invention relates to a coding strategy for joint modulation coding and ECC coding. It relates in particular to the situation where 2D coding is performed along one-dimensionally evolving strips containing a number of bit rows in the radial direction of the strip, which is orthogonal to the former direction. The idea further relates to high-rate modulation coding. According to the invention, a strip is built up by an alternation of two basic sub-units, each with their own modulation code. The first sub-unit comprises a larger number of bit rows, and its (high-rate) modulation code has a high coding efficiency realized through the use of large codewords.

Abstract: An optical scanning device for scanning an optical record carrier comprising an information layer. Crosstalk cancellation is provided using a phase modulating element (40, 140) for generating a non-rotationally-symmetric phase profile in a subsidiary radiation beam. The phase profile varies with an azimuthal angle measured about the optical axis of the beam portion, the phase profile varying such that successively different phases are introduced in at least five locations which are each at successive azimuthal angles (?1, ?2, ?N) and each at a given radial distance from the optical axis, wherein the phase profile is such that the phases introduced, when taken in modulo 2? form, successively cycle through 0 to 2? at least twice, whereby the subsidiary beam spot is provided with an intensity distribution on the information layer which overlaps that of the side-lobe of the main beam spot.

Abstract: The present invention relates to a Viterbi bit detection method for detecting the bit values of bits of a channel data stream stored on a record carrier along an N-dimensional channel tube, N being at least two, of at least two bit rows one-dimensionally evolving along a first direction and being aligned with each other along at least a second of N-1 other directions, said first direction together with said N-1 other directions constituting an N-dimensional lattice of bit positions, comprising application of a row-based one-dimensional Viterbi bit detection method independent for each of the bit rows of said channel tube.

Abstract: The invention relates to an interference-free LMS-based asynchronous receiver for digital transmission and recording systems. The receiver, having an asynchronously placed LMS-based adaptive equalizer, has 2 control loops: a timing recovery loop (by means of, for instance a PLL (Phase locked loop) and an equalizer's adaptation loop. Interference between the two loops is avoided by deriving a condition the equalizer should fulfill to avoid the interference between the two loops, which implies “orthogonal control functionality” and by combining the condition with the equalizer's adaptation loop. The equalizer shall adapt so that the condition is always true.

Abstract: The invention relates to a method of multi-dimensionally encoding a user data stream of user words into a channel data stream of channel words evolving in a one-dimensional direction of infinite extent. The invention relates further to a corresponding method of decoding.

Abstract: The invention relates to a signal comprising a runlength limited (RLL) encoded binary d,k channel bitstream 3, wherein parameter d defines a minimum number and parameter k defines a maximum number of zeroes between any two ones of said bitstream 3 or vice versa, comprising a number of sections of respectively N successive RLL channel bits, called RLL rows 8-13, 45, each RLL row 8-13, 45 representing a parity-check code-word, called row parity-check code-word, in which a so-called row-based parity-check constraint for said RLL row 8-13. 45 has been realized, characterized in that K sections of respectively N successive channel bits, called column parity-check rows 21, 22, 43, 44, 46, are located at predetermined positions of a group of M RLL rows 8-13.