Abstract: An information reproducing apparatus (1) is provided with: a waveform shaping device (14) for performing waveform shaping on a read signal (RRF) read from a recording medium (100), on the basis of a reference amplification factor; a correcting device (18) for correcting waveform distortion occurring in a read signal corresponding to at least a long mark, of the read signal on which the waveform shaping is performed; and a waveform equalizing device (15) for performing a waveform equalization process on the read signal in which the waveform distortion is corrected, the waveform shaping device arbitrarily increases the reference amplification factor.

Abstract: A disk recording medium which can implement a recording method having a high degree of reliability for additional information is disclosed. The disk recording medium has a recording and reproduction region into and from which first data can be recorded and reproduced in accordance with a rewritable or write-once-read-many recording method and from which second data recorded in the form of wobbling of a groove can be reproduced. The second data includes address information and additional information. The additional information of the second data is coded in accordance with a first error correction method, and the coded additional information and the address information are recorded in a state coded in accordance with a second error correction method.

Abstract: The focus offset FE0 corresponding to minimum jitter is learned in advance. When performing spherical aberration adjustment for each disk, the spherical aberration is adjusted so that the jitter reaches a minimum, while maintaining the focus offset at FE0. The invention provides a method for performing high-precision adjustment of the focus offset and spherical aberration, even in the case of a disk which does not have data recorded on it.

Abstract: To provide a disk reproducing apparatus capable of reading data at a lower error rate without requiring a complicated circuit configuration. An embodiment of the present invention provides a disk reproducing apparatus for reproducing a data signal based on a signal read from a disk and having a clock cycle that is an integral multiple of a cycle of a reproduction clock, including: a clock generating unit generating the reproduction clock based on an input signal obtained by binarizing the signal read from the disk; an error component detecting unit detecting an error component in the input signal; a threshold storage unit storing a threshold value for determining the error component; and a data signal reproducing unit reproducing the data signal in the input signal based on the error component detected by the error component detecting unit and the threshold value stored in the threshold storage unit.

Abstract: In a circuit for detecting a recorded area of an optical disk, when unnecessary noise is superimposed on the space portion of the digitized signal (RF) of an RF signal from the optical disk, a counter (20) for detecting a space portion detects the noise and resets a counter (81) for detecting a recorded area with an output signal S21 therefrom. This prevents the counter (81) for detecting a recorded area from erroneously outputting a recorded area detection signal (S12) due to the noise. As a result, a counter (80) for detecting an unrecorded area outputs an unrecorded area detection signal (S20) with high accuracy to bring a recorded area signal (RECD) from a flip-flop circuit (82) to the L level. Accordingly, an unrecorded area can be detected as it is inherently with high accuracy without being erroneously recognized as a portion in which a mark portion has been recorded.

Abstract: Methods and structures for performing field flawscan to reduce manufacturing costs of a dynamic mapped storage device. In a dynamic mapped storage device in which all user supplied logical blocks are dynamically mapped by the storage device controller to physical disk blocks, features and aspects hereof permit flawscan testing of a storage device to be completed substantially concurrently with processing write requests for its intended application. A fraction of the storage device may be certified by an initial flawscan performed during manufacturing testing. Statistical sampling sufficient to assure a high probability of achieving specified capacity may be performed to reduce manufacturing time and costs in testing. Final flawscan of the remainder of the storage locations may be performed substantially concurrently with processing of write requests after the device is installed for its intended application.

Abstract: A reading unit for reading data from a digital data carrier, the reading unit comprising: a reading head including a sensor for sensing data from the data carrier and generating a sensor signal indicative for the sensed data; head positioning apparatus for positioning the head relative to the data carrier in response to a head positioning control signal; a head positioning controller for receiving the sensed data and being operable in accordance with a stored instruction set to process the sensed data to generate the head positioning control signal; and a data decoder for decoding the sensed data to form a digital output signal.

Abstract: The present invention discloses an apparatus for generating a TE signal in an optical disc drive. The disclosed apparatus includes a signal generation module, a quality detection module coupled to the signal generation module, and a signal-synthesizing module coupled to the signal generation module and the quality detection module. The signal generation module generates a first and a second candidate TE signal according to a light beam reflected off an optical disc. The quality detection module estimates the signal quality of the first and/or the second candidate TE signal and controls the signal-synthesizing module accordingly. The signal-synthesizing module generates the TE signal according to the first and/or the second candidate TE signal.

Abstract: The resistance against recording defects of a write-once optical disk is enhanced allowing realtime recording and playback of data streams with a single speed disk drive. A data stream is recorded in data blocks on the optical disk. An error correction block for one or more data blocks is generated and written on the same optical disk during recording. A spare data area is kept blank on the storage medium and used for storing a defect data block reconstructed by using the error correction block.

Abstract: A recording and reproducing area and a reproduction-only area are formed by wobbling a groove formed in a spiral fashion to form a track to be tracked on a disk. The recording and reproducing area has address information recorded by wobbling of the groove and information recorded and reproduced by phase change marks on the track formed by the groove where the address information is recorded. The reproduction-only area has prerecorded information recorded by wobbling of the groove.

Abstract: A data read system comprising a read channel for processing a signal, and a diagnostic controller in communication with the read channel. The diagnostic controller is configured to measure at least one metric of the read channel during processing of a signal containing unknown data. The measured metric is then compared against a stored nominal metric and a warning is generated in response to a result of the comparison. In particular, the warning is generated only if the difference between the measured metric and the stored nominal metric exceeds a threshold.

Abstract: Before initiation of tracking control, an optical disk device performs an offset amount obtaining operation, in which a difference between a middle value of the amplitude of a tracking error signal and a predetermined reference value is obtained as an offset amount. After the initiation of the tracking control, the optical disk device initiates an attenuation operation, in which an offset amount attenuation section attenuates the offset amount obtained by the offset amount obtaining operation to obtain an attenuated offset amount, while initiating, with an initial value being 0, an estimation operation, in which an observer estimates the offset amount according to a tracking driving signal to obtain an estimated offset amount. The optical disk device corrects the tracking error signal by using the attenuated offset amount obtained by the attenuation operation and the estimated offset amount obtained by the estimation operation.

Abstract: According to one embodiment, an optical disk device includes a semiconductor laser, a circuit which generates a timing signal to determine a recording pulse timing, a circuit which sets a magnitude of a current for the laser, a circuit which switches the magnitude of the current according to the timing signal, a generation circuit which generates a correction signal from the timing signal to correct response characteristics of a recording pulse, a circuit which synthesizes the correction signal and signals obtained as the switch result to determine the magnitude of the current, and a circuit which feeds the current to the laser according to the synthesis result. The generation circuit extracts high-frequency components from the signals obtained as the switch result and the signal generated by the synthesis circuit, and switches a frequency and a signal gain of each of the components, in accordance with recording pulse conditions.

Abstract: An information recording medium in which bottoms of a guide groove and a pit array formed on a disc substrate are allocated on a same flat plane and shaped in flat. Further, in a transition area from a pit array to a guide groove or from a guide groove to a pit array, the information recording medium is provided with an intermediate area composed of a pit array of which height changes from a height between a bottom and a side of a groove to another height between the bottom and a side of the pit array.

Abstract: In a DPP-type tracking error signal (TE signal), an offset caused by the difference between the reflectance of a main-beam irradiated part and the reflectance of side-beam irradiated parts is appropriately compensated without individual normalization of an MPP signal and an SPP signal. An analog signal processing unit 40 produces the MPP, MPI, SPP, and SPI signals on the basis of the amounts of received reflected light of the main beam and side beams detected by a photo-detection unit 130, produces a DPP-type TE signal and a CE signal on the basis of the MPP and/or SPP signal, and outputs the analog signals of the TE, CE, MPI, and SPI signals.

Abstract: An information recording medium in which bottoms of a guide groove and a pit array formed on a disc substrate are allocated on a same flat plane and shaped in flat. Further, in a transition area from a pit array to a guide groove or from a guide groove to a pit array, the information recording medium is provided with an intermediate area composed of a pit array of which height changes from a height between a bottom and a side of a groove to another height between the bottom and a side of the pit array.

Abstract: An information recording medium in which bottoms of a guide groove and a pit array formed on a disc substrate are allocated on a same flat plane and shaped in flat. Further, in a transition area from a pit array to a guide groove or from a guide groove to a pit array, the information recording medium is provided with an intermediate area composed of a pit array of which height changes from a height between a bottom and a side of a groove to another height between the bottom and a side of the pit array.

Abstract: An optical recording device includes a light source, a spatial light modulator, a correcting optical system and a light guiding section. The spatial light modulator includes plural pixels, a signal light region that displays a signal light pattern, and a reference light region that displays a reference light pattern. The spatial light modulator modulates and outputs incident light for each pixel in accordance with a display pattern. The correcting optical system includes a pair of axicon lenses that correct the emitted light from the light source so as to flatten the light intensity distribution thereof on an irradiated surface of the spatial light modulator. The light guiding section guides the corrected light to the spatial light modulator. The signal light and the reference light are irradiated onto an optical recording medium simultaneously and a hologram is recorded into the optical recording medium.

Abstract: An information recording medium in which bottoms of a guide groove and a pit array formed on a disc substrate are allocated on a same flat plane and shaped in flat. Further, in a transition area from a pit array to a guide groove or from a guide groove to a pit array, the information recording medium is provided with an intermediate area composed of a pit array of which height changes from a height between a bottom and a side of a groove to another height between the bottom and a side of the pit array.

Abstract: An information recording medium in which bottoms of a guide groove and a pit array formed on a disc substrate are allocated on a same flat plane and shaped in flat. Further, in a transition area from a pit array to a guide groove or from a guide groove to a pit array, the information recording medium is provided with an intermediate area composed of a pit array of which height changes from a height between a bottom and a side of a groove to another height between the bottom and a side of the pit array.

Abstract: A method for adjusting at least one alignment control axis of a holographic data storage system or device to or towards a sufficiently optimal recovery position for recovery of a hologram based on a derived feedback error signal and/or a derived feed-forward signal. For the next hologram in the sequence, the derived feedback error signal estimates the direction and magnitude of misalignment of the at least one alignment control axis for one or more previously recovered holograms based on alignment-indicating data. The derived feed-forward signal estimates an optimal alignment value for the at least one alignment control axis for one or more holograms based on recording and recovery operating condition data for the holograms. An iterative alignment procedure may also be used to derive a feedback error signal for one hologram.

Abstract: An information recording medium in which bottoms of a guide groove and a pit array formed on a disc substrate are allocated on a same flat plane and shaped in flat. Further, in a transition area from a pit array to a guide groove or from a guide groove to a pit array, the information recording medium is provided with an intermediate area composed of a pit array of which height changes from a height between a bottom and a side of a groove to another height between the bottom and a side of the pit array.

Abstract: An information recording medium in which bottoms of a guide groove and a pit array formed on a disc substrate are allocated on a same flat plane and shaped in flat. Further, in a transition area from a pit array to a guide groove or from a guide groove to a pit array, the information recording medium is provided with an intermediate area composed of a pit array of which height changes from a height between a bottom and a side of a groove to another height between the bottom and a side of the pit array.

Abstract: A digital data demodulator which can reduce a loss of decodable digital data, and increase capability of reproducing digital data inputted through a transmission line even when an error occurs in the transmission line. In the digital data demodulator, a specific pattern detector (113) detects a specific pattern to be included in a modulation code, from a bit string inputted through a transmission line (104). A modulation code identifying unit (117) generates a demodulation data strobe signal (119) according to a phase of the modulation code including the specific pattern. An error corrector (121) samples demodulation data (109) in response to the demodulation data strobe signal (119) and reproduces the data to the original digital data.

Abstract: A phase error detection apparatus capable of performing offset correction of a tracking error signal accurately even when there is a defect or a non-recorded position on an optical disc. There are provided a phase difference detection circuit (107) which receives two sequences of digital signals, performs phase comparison using a distance between zerocross points of the two sequences of digital signals, and outputs a phase comparison result PCR and a phase comparison completion signal PCC, and an offset control circuit (11) which outputs an offset correction amount for each phase comparison completion signal PCC from the phase difference detection circuit (107), and the offset correction amount ?? is added to the phase comparison result PCR to avoid offset correction in a position where phase comparison is not carried out.

Abstract: A reproducing device includes a detection circuit and an integration circuit. The detection circuit detects a push-pull signal PP. The integration circuit carries out integration processing with respect to one or greater frames of the push-pull signal, and carries out binarization processing with respect to integration results thus obtained, thereby detecting sub data. In the integration circuit, the more the frames to be used for detecting sub data is, the higher the accuracy of the detected sub data is. The reproducing device further includes a control circuit for controlling the total number of the frames to be used for generating valid sub data in the integration circuit. The control circuit controls the total number of the frames in accordance with a result of an error correction made by an error correction circuit.

Abstract: A waveform shaping portion receives a digital reproduced signal generated from an analog reproduced signal reproduced from an information recording medium and shapes the waveform of the digital reproduced signal. A maximum likelihood decoding portion applies maximum likelihood decoding to the digital reproduced signal in the shaped waveform and generates a binarized signal indicating the result of the maximum likelihood decoding. A phase detection portion extracts, during the maximum likelihood decoding, a phase error using state transition patterns having only a single zero cross point among differential metrics at a plurality of merging points at which a set of paths branched from a given state merges. A synchronization detection portion generates a reproduction clock signal using the phase error that has been detected and brings the digital reproduced signal into synchronization with the reproduction clock signal that has been generated.

Abstract: An optical disc playback apparatus includes an optical pickup, an RF amplifier that generates a tracking error (TE) signal based on an electrical signal from the optical pickup, a defect detector that detects a defect on the optical disc and that outputs a DFCT signal indicating the detected defect, a switch that outputs a hold signal when a defect is detected based on the DFCT signal, a driver that controls the optical pickup based on the output signal of the switch, a corrector that extracts an oscillation component of the optical pickup from the TE signal in response to the DFCT signal when a defect is detected and that outputs a correction signal indicating the oscillation component, and an adder that adds the correction signal from the corrector to the hold signal.

Abstract: An optical disc reading apparatus, such as a Near Filed optical disc reading apparatus, comprises a disc reader (401) which generates a first signal by reading an optical disc (403). A bit detector (407) detects data values in response to the first signal. The detected data is fed to an error correction processor (407) which performs error correction on the stream of detected data. In addition, the reading apparatus comprises an error signal processor (411) which generates a reading head position error signal. The error signal may for example be indicative of an air gap error or a tracking error for the reading lens. The error signal is fed to a reliability processor (413) which sets reliability values of at least some of the detected data in response to the head position error signal. The error correction performed by the error correcting processor (407) then performs the error correction taking the reliability values into account. The invention may allow improved error correction performance.

Abstract: A device providing for microstructuring a storage medium includes a radiation source for producing an at least partially coherent beam from electromagnetic radiation, a modulator-provided with a plurality of individually switchable modulator elements, a beam-forming optical element for illuminating the modulator, a reducing optical element for reducing a beam radiated by the modulator, and a transport table for displacing the storage medium in relation to the reducing optical element. The device solves technical problems caused by writing of microstructuring and individual diffractive optical elements, in particular computer-generated holograms having a high speed and high writing energy. The device is achieved in that the reducing optical element is configured with limited diffraction and produces a surface reduction of at least 25 from a surface of the individually switchable modulator elements.

Abstract: A method for inspecting an optical information storage medium includes the steps of: irradiating the storage medium with a laser beam and rotating the medium by a constant linear velocity control technique by reference to the radial location at which the laser beam forms a spot on the medium; changing the rotational velocities according to the radial location on the medium between at least two linear velocities that include a first linear velocity Lv1 and a second linear velocity Lv2 higher than the first linear velocity Lv1; generating a focus error signal and/or a tracking error signal based on the light reflected from the medium; performing a focus control and/or a tracking control on the laser beam that irradiates the medium based on the focus and/or tracking error signal(s); and passing the branched outputs of control loops for the focus and/or tracking error signal(s) through predetermined types of frequency band-elimination filters for the focus and/or tracking error signal(s) to obtain residual errors

Abstract: An optical recording medium having a track on which data has been previously recorded, comprising on the track a plurality of data block regions each of which includes main data of a block which is divided into a predetermined number of main data pieces, each of which has data for identifying the main data, and linking regions each of which has pseudo data and is inserted between the data block regions. When the linking regions on said track are adjacent, recording patterns of the pseudo data of the adjacent linking regions are different from each other. Further provided is a recording apparatus forming the data block regions and linking regions on a recording medium.

Abstract: A recording and/or reproducing method, a recording and/or reproducing apparatus, and a computer readable recording medium storing a program for performing the method. A recording unit block in which invalid data is partially padded is written on an information storage medium along with padding information indicating that the invalid data is included in the recording unit block. The padding information is useful in determining whether the recording unit block includes the padding data. Accordingly, unnecessary retrial processes of a drive system are reduced such that the performance of the drive system is improved and error correction capability is enhanced.

Abstract: An optical information reproduction apparatus for reproducing a recording signal by irradiating a light beam onto a recording surface of an optical information recording medium having at least two information recording layers and by receiving reflected light of the light beam is provided. The optical information reproduction apparatus includes an extraction section for extracting an envelope signal of a reproduction signal when the reproduction signal reproduced by focusing the light beam onto one information recording layer in the plural information recording layers has been modulated by interlayer crosstalk from another information recording layer; and a distortion correction section for correcting the distortion of the target reproduction signal caused by the interlayer crosstalk by gain-adjusting the reproduction signal containing DC components so that the envelope signal becomes constant.

Abstract: A method for recovering video data in a disk when a reading error occurs is provided. First, the disk is scanned to obtain a next writable address (NWA) of a last video chapter previously recorded into the disk. An end address of a successfully recorded video chapter is then read from a specific area of the disk and stored into a memory. Next, when a disk player/recorder is requested to read content of data according to the NWA, the disk player/recorder determines whether the content of the data is a file system. If the content of the data is not a file system, the NWA obtained by scanning the disk is replaced with the end address read from the specific area to read the file system, so as to recover the video data in the disk. Thereby, the video data in the disk can be protected.

Abstract: An information recording medium includes a lead-in area and a data area for storing contents information. The lead-in area includes a first lead-in information area and a second lead-in information area. The first lead-in information area corresponds to a first playback mode. The second lead-in information area corresponds to a second playback mode different from the first playback mode. The first lead-in information area has a first depth and is designed for storing lead-in information related to the contents information stored in the data area. The second lead-in information area includes pre-pits having a second depth greater than the first depth. The pre-pits represent predetermined information, such as information of copyright protection, related to the contents information stored in the data area.

Abstract: The present invention relates to an optical recording apparatus capable of recording information on an optical record carrier. Radial tracking control is performed by the 3 spot differential push pull (PP) method. The optical recording apparatus has means for obtaining a first and second difference signal from detection signals of a reflection of a main light beam (C) and a first and a second sub light beam (A,B), and means for subtracting the second difference signal from the first difference signal so as to obtain a tracking error signal (TES). The second difference signal is adjusted by a gain factor (g) so as to compensate for a difference in intensity between the reflected light of the first and the second sub light beams during information writing. In particular, a solution may compensate for the difference in the reflections for the first and second sub light beam (A,B) so that a possible radial offset is avoided.

Abstract: A position control method is disclosed that is capable of precisely and stably controlling a position of an object lens relative to a recording medium. When controlling the position of the object lens in the tracking direction, first, an attempt is made to read address information recorded on the recording medium, and if the address information is not readable, the polarity of the tracking error signal used for servo control is reversed. As a result, even for a recording medium of a low quality or a nonstandard recording medium, which are treated as invalid media in the related art, it is possible to locate the object lens to the target position.

Abstract: An apparatus and method to modulate address data of a disc type recording medium, include generating the address data, performing error correction coding of the address data and outputting coded address data, receiving the coded address data in a unit of at least two bits, generating a first modulated signal of the coded address data using a first modulation technique, generating a second modulated signal of the coded address data using a second modulating signal, and generating a unit wobble signal by synthesizing the first and second modulated signals.

Abstract: In an information recording, a first data processor divides input data into a plurality of frames so as to arrange the plurality of frames for each unit block. The unit block is a unit of error-correction with respect to the input data and the frames include first identification information, respectively. A second data processor inserts a linking block on a boundary portion between unit blocks in the record data. The unit blocks are adjacent to each other. The linking block includes a second identification information and the second identification information is different from each of the first identification information. A controller controls to record the unit block and the linking block on the information recording medium.

Abstract: The invention relates to a method of writing data to a disc (OD). The method comprising a) performing a writing action in which a first data portion is written to the disc; a2) deciding to perform b) or not and b) verifying at least part of the first data portion that is written to the disc and deciding to replace the first data portion that is written to the disc or not. Finally the method comprises c) performing a further writing action in which a second data portion is written to the disc.

Abstract: A plurality of retry tables is used for adaptive and flexible error correction during a read/write operation within a disk drive. The plurality of retry tables is stored in a data storage unit, and one of the retry tables is selected to be used for the error correction. In addition, firmware is not modified for using any of the plurality of retry tables during the error correction. One of the retry tables becomes eventually selected as being optimum for the error correction depending on an application, operating conditions, and head/mechanical characteristics of the disk drive.

Abstract: An apparatus and a method removing offset of a Phase Lock Loop (PLL) circuit in a disc drive without using a disc when data playback is performed, the apparatus including an ENDEC module and a PLL circuit. The ENDEC module outputs a binary signal if an offset removal mode is set. The PLL circuit removes the offset of the PLL circuit by comparing a phase of the binary signal with a phase of a channel bit clock signal. Therefore, a time to remove the offset of the PLL circuit is reduced and the possibility not to remove the offset of the PLL circuit due to a damaged disc is prevented.

Abstract: A bit detector (203) for an optical disc reading apparatus comprises an interface (401) which receives central aperture signal values from an optical disc reader (101). The interface is coupled to a threshold detector (403) which assigns a first data value to data bits having corresponding central aperture signal values above a first threshold and a second data value to data bits having corresponding central aperture signal values below a second threshold. The thresholds are set to provide high reliability of the assigned data values and to restrict the data resulting in central aperture signal values between the thresholds to minimum run length sequences. A run length detector (405) assigns data values to at least one data bit of a sequence of data bits having corresponding central aperture signal values between the first and second threshold in response to a run length coding of the data bits and a data value of at least one data bit adjacent to the sequence.

Abstract: An aligned write signal generator with alignment calibration utilizes an alignment unit to align a plurality of write signal. The aligned write signal generator includes a write signal generator for receiving an EFM signal and converting the EFM signal into a plurality of write signals according to a write strategy waveform generating rule, an alignment unit for receiving the plurality of write signals, aligning the write signals and outputting phase adjusted write signals, and a phase calibration unit for receiving the phase adjusted write signals, detecting phase error between the phase adjusted write signals, and outputting phase control signals. The alignment unit further receives the phase control signals to adjust the delay time of each write signal.

Abstract: A system and method for detecting degeneration in an optical media by defining a set of error correction code (ECC) blocks uniformly on an optical media and reading each of the ECC blocks to determine a number of correctable errors for each of the ECC blocks once the optical media is placed into use. The result of the reading of the ECC blocks is stored on the optical media. The reading of the ECC blocks can be a repetitive reading of each of the ECC blocks with the results for each of the ECC blocks averaged. Each ECC block from the set is readout several times and for each ECC block the average number of ECC Corrections is memorized also on disc. Degeneration of the optical should be uniform over the disc. By performing the reading of the ECC blocks over a long period of time, long term degradations of the disc can be determined and an indication made that data on the disc should be copied to another storage device.

Abstract: In an optical disk of HD-DVD, data is recorded in both grooves and lands. A groove track includes its own data region called a groove (G) track address system formed therein and a land track includes its own data region called a land (L) track address system formed therein. One bit of address data is composed of four redundant wobble waves. When only three or two of the four wobble waves can be detected, an error is determined. When an error is determined in tracing of a groove track, bit data of the L track address system is used to correct the error. When an error is determined in tracing of a land track, bit data of the G track address system is used to correct the error.

Abstract: In an information recording, a first data processor divides input data into a plurality of frames so as to arrange the plurality of frames for each unit block. The unit block is a unit of error-correction with respect to the input data and the frames include first identification information, respectively. A second data processor inserts a linking block on a boundary portion between unit blocks in the record data. The unit blocks are adjacent to each other. The linking block includes a second identification information and the second identification information is different from each of the first identification information. A controller controls to record the unit block and the linking block on the information recording medium.

Abstract: The invention discloses a decoding apparatus and the method thereof for decoding a signal retrieved by an optical information reproducing system from an optical information recording medium. N legal codes are predetermined. According to the invention, first, the retrieved signal is converted into a data stream. Then, in a Viterbi decoding manner, the data stream is decoded into a digital code in accordance with a level of the data stream and N reference levels. Then, the binary code is decoded by a binary array into one of the N legal codes, and each of the N legal codes corresponds to one of N reference levels. In particular, the N reference levels are corrected by various detected conditions to enhance the correctness of decoded data.

Abstract: A calibration method for a slice level of zero cross signal and a method of producing zero cross signal are disclosed. In this invention, the positive cycle and the negative cycle of the zero cross signal are sampled to obtain an error value related to the slice level due to asymmetry of the zero cross signal. By this invention, the asymmetry between the positive cycle and the negative cycle of the zero cross signal can be adjusted.