Abstract: An apparatus and method detecting synchronization of address in pre-groove (ADIP), allowing an optical storage device to write data to an accurate location of a disc includes a bit synchronization detecting unit and a word synchronization detecting unit. The bit synchronization detecting unit determines synchronization of bits of the ADIP to be in a bit synchronization locked state when synchronization of raw bits is detected within a bit synchronization window having a first predetermined period a first predetermined number of consecutive times. The word synchronization detecting unit determines synchronization of words of the ADIP to be in a word synchronization locked state when synchronization of raw words is detected within a word synchronization window having a second predetermined period the first predetermined number of consecutive times.

Abstract: A control circuit for an optical disk drive includes a frequency detector, a phase detector, a low pass filter, a voltage-controlled oscillator (VCO), and a controller. The frequency detector and the phase detector both receive an eight-to-fourteen modulation (EFM) signal and a data phase-locked loop (DPLL) signal. The controller can calculate a target frequency and control the VCO to output the DPLL signal according to the target frequency. During a non-seek mode, the VCO outputs the DPLL signal according to output of the frequency detector, phase detector, and low pass filter. During a seek mode or when spindle speed of the optical disk drive changes, the VCO outputs the DPLL signal according to the target frequency. The controller further outputs charge pump currents for the frequency detector and the phase detector and sets an RF equalizer signal and a differential phase detector (DPD) equalizer signal according to the target frequency.

Abstract: A noise removal circuit of the present invention comprises a 180-degree odd multiple shifting section for outputting a 180-degree shifted signal that is phase-shifted from an input signal by an odd multiple of 180 degrees and difference output section for outputting a difference between the input signal and the 180-degree shifted signal. The noise removal circuit comprises a 360-degree shifting section for outputting a 360-degree shifted signal that is phase-shifted from an input signal by an integral multiple of 360 degrees and sum output section for outputting a sum of the input signal and the 360-degree shifted signal.

Abstract: Data not stored in the DRAM array of a SDRAM module is read from the SDRAM module in a synchronous data transfer. The data transfer, referred to as register read command/operation, resembles a read command/operation directed to data stored in the DRAM array in timing and operation. The register read command is distinguished by a unique encoding of the SDRAM control signals and bank address bits. In one embodiment, the register read command comprises the same control signal states as a MSR or EMSR command, with the bank address set to a unique value, such as 2?b10. The register read command may read only a single datum, or may utilize the address bus to address a plurality of data not stored in the DRAM array. The register read operation may be a burst read, and the burst length may be defined in a variety of ways.

Abstract: A protecting device installed in an optical storage system for protecting a plurality of physical identification data synchronous signals includes a synchronous pattern detecting device, a data synchronous signal insertion device for adding the amount of data synchronous signals to a first predetermined number, a counting/reloading device for sequentially counting the first predetermined number of data synchronous signals and an additional second predetermined number of data synchronous signals, a PID window generator for generating a plurality of protecting windows respectively corresponding to the plurality of physical identification data synchronous signals while the counting/reloading device is counting the second predetermined number of data synchronous signals, and a PID synchronous signal protection device for protecting the plurality of physical identification data synchronous signals according to the plurality of protecting windows.

Abstract: A synchronization circuit for an optical disc apparatus, which performs synchronization operation based on a playback signal of an optical disc, the circuit comprises a playback signal recovery timing detection circuit that detects timing corresponding to the recovery of the playback signal for a defect signal from a defect signal detection circuit, a delay counter that counts frame synchronization signals from timing at which loss of recorded data on the optical disc is not detected by the defect signal detection circuit, a delay determining circuit that determines whether a count of the frame synchronization signals by the delay counter has reached a predetermined delay count, and a circuit that starts the synchronization operation when informed by the delay determining circuit to the effect that the count of the frame synchronization signals has reached the predetermined delay count.

Abstract: Data not stored in the DRAM array of a SDRAM module is read from the SDRAM module in a synchronous data transfer. The data transfer, referred to as register read command/operation, resembles a read command/operation directed to data stored in the DRAM array in timing and operation. The register read command is distinguished by a unique encoding of the SDRAM control signals and bank address bits. In one embodiment, the register read command comprises the same control signal states as a MSR or EMSR command, with the bank address set to a unique value, such as 2'b10. The register read command may read only a single datum, or may utilize the address bus to address a plurality of data not stored in the DRAM array. The register read operation may be a burst read, and the burst length may be defined in a variety of ways.

Abstract: An apparatus for generating a wobble clock includes an operation circuit for receiving a wobble signal and counting cycles of an oscillating signal during a cycle of the wobble signal to derive a cycle value and for comparing the cycle value with a preset cycle value to output a first protection signal, and a phase-locked loop circuit connected to the operation circuit for receiving the wobble signal, the wobble clock and the first protection signal, and determining whether the wobble clock is to be synchronized with the wobble signal according to the first protection signal.

Abstract: A method and apparatus for detecting information recorded as a phase-modulated wobble along a track of an optical disk, whereby a reference phase section is recorded with wobble having a predetermined reference phase and whereby respective polarities of phase integration values obtained by synchronous detection of phase-modulated unit sections following the reference phase section, in a playback wobble signal, are compared with the polarity of a reference phase integration value obtained for the reference phase section, to thereby detect respective bit states expressed by the phase-modulated unit sections.

Abstract: A method for optical drive decoding of address in pre-groove (ADIP) data is provided to decode an input wobble signal to an ADIP unit signal. The method includes generating a wobble carrier frequency signal having the same phase with the wobble signal, multiplying the wobble carrier frequency signal by the input wobble signal to generate a product signal, accumulating the value of the product signal in each clock to generate a quotient summation signal, determining the phase change of the input wobble signal according to the value of the quotient summation to generate a phase change signal, and generating the ADIP unit signal by comparing the phase change signal with a plurality of ADIP patterns.

Abstract: An optical recording method and apparatus with different recording rates are provided for effectively increasing the average recording rate. The optical recording method includes the steps of: controlling a recording rate with a constant linear velocity (CLV) control mode; recording data; judging whether the recording rate has to be increased according to a rotating speed of a spindle motor or a recording position; and performing a process for changing the rotating speed if the recording rate is increased, and continuing recording data at the same recording rate if the recording rate is not increased. The step for changing the rotating speed includes the steps of: pausing recording data; registering a paused zone of a disc; determining a new rotating speed of the spindle motor, and driving the spindle motor at the new rotating speed; and linking recording zones to continue recording data at a new recording rate from the paused zone, when the rotating speed of the spindle motor is stable.

Abstract: The invention provides a phase lock loop (PLL) in a controller of an optical disk system and methods therefor. According to a preferred embodiment of the invention, the PLL comprises a write phase detector, a read phase detector, and a common read/write module shared by the write and read phase detectors. Further according to the invention, the common read/write module comprises a read/write mode selector coupled to the write and read phase detectors, a charge pump coupled to the mode selector, a loop filter coupled to the charge pump, and a voltage control oscillator (VCO) coupled to the loop filter.

Abstract: As the result of the detection of the runaway of the optical disc when the light pickup cannot detect sync signal in the reproducing signal sent from the optical disc, the control circuit turns off the tracking servo mechanism which controls the tracking of the optical disc by the light pickup. The direction of rotation of the optical disc that is running away is detected by comparing the initial mirror count value obtained by counting for a predetermined period of time the mirror pulse detected in correspondence with the RF signal based on the reproducing signal, with the mirror count value during braking obtained by counting the mirror pulse for the predetermined period of time when the spindle motor is applied with the brake pulse. The brake signal working in the direction opposite to the detected direction of rotation is applied to the spindle motor so as to stop the rotation of the optical disc.

Abstract: A laser beam recording system for exposing a photoresist master disc having a photoresist layer formed over a substrate for making a hybrid optical recording disc having a read only (ROM) portion and a writable portion, including a first optical modulator for modulating an intensity of a first laser beam having a wavelength selected to provide activating radiation to expose a pattern in the photoresist layer formed over the substrate of the master disc between a lower intensity for exposing a groove in the photoresist layer and a higher intensity for exposing the groove and a pattern of depressions in the groove in the photoresist layer; and a second optical modulator for frequency-modulating an intensity-modulated second laser beam with a wobble-frequency to cause the exposed groove to be a continuously frequency-modulated groove.

Abstract: An optical disk device that records and reproduces information on/from a recordable optical disk is provided.

Abstract: An apparatus for recording data on and reproducing data from the disk in which a recording area is divided into sectors, includes a reproducing signal generator for generating a reproducing signal including sum signals V1 and V2 of radial pairs, a sum signal RF_sum, and a push-pull signal RF_pp from an optical signal reflected from the disk, a header area detector for generating a header area signal including a header area from the reproducing signal, a first synchronous signal level detector for detecting a magnitude Ivfo1 of a first synchronous signal in the first header by being synchronized with the header area signal, a second synchronous signal level detector for detecting a magnitude Ivfo3 of a second synchronous signal in the second header by being synchronized with the header area signal, and a balance calculator for calculating the balance of the magnitude Ivfo1 and the magnitude Ivfo3.

Abstract: A method and apparatus for normalized bit counting is described. The method comprising incrementing a bit counter using a first clock, and adjusting a target bit based on a difference in frequency between the first clock and a second clock. The method further comprising determining when the bit counter reaches the adjusted target bit.

Abstract: The present invention relates to a method of changing a recording mode from CAV (Constant Angular Velocity) mode to CLV (Constant Linear Velocity) mode in the middle of recording data to a disk recording medium. A method according to the present invention reads ATIP-framed data encoded in a wobble signal formed along a spiral physical track while recording input data to a recording medium, and detects a sync signal contained in the read ATIP-framed data. Another method measures the frequency of a low-frequency component of the wobble signal instead of reading ATIP-framed data. These two methods determine, in common, when to change the recording mode from CAV to CLV based on the period of the detected sync signal or the measured frequency. The present invention makes it possible to record input data to an entire area of a disk more rapidly without fatal errors such as imperfect writing. As a result, total recording time can be reduced with stable recording guaranteed.

Abstract: A method and device for controlling a rotation speed of a spindle of an optical disk drive includes a frequency detector, two phase detectors, a frequency divider, a low pass filter, a switch circuit, and a drive circuit. The method uses a wobble signal, an encoder EFM frame synchronization (EEFS) signal, an encoder subcode frame synchronization (ESFS) signal, and other related signals to generate five control signals for controlling the rotation speed of a motor connected to the spindle of the optical disk drive. Using the five control signals, the method limits the phase difference between the Absolute Time in Pre-groove (ATIP) sync and the ESFS to be within a predetermined value, and thus improves an update rate and a writing efficiency.

Abstract: Methods and apparatus for using physical synchronization markers during optical disc data acquisition are provided. In accordance with this invention, physical synchronization markers on optical discs and/or disc covers can be used to determine absolute and/or relative positions on the disc or cover and control data acquisition. A method for acquiring data includes detecting at least one physical synchronization marker and reading data in response to detecting the marker.

Abstract: A first delay circuit receives a sampling clock obtained by multiplying detected frequency of reference clock patterns and outputs delay clocks from first delay stages, respectively. Recording frequency of the sampling clock is not obtained using the reference clock patterns but obtained using received addresses. A disk driving apparatus obtains the number of the first delay stages to be used which correspond to one cycle of the obtained recording frequency and necessary for phase adjustment of the sampling clock, and disables not-used first delay stages. Any of the delay clocks is selected and at least one of regenerating operation to read data from a disk media and recording operation to write data thereto is executed in synchronization with the selected delay clock. Consequently, the number of delay stages to be disabled can be obtained with simple control, reducing power consumption of circuits for adjusting phases of the sampling clocks.

Abstract: A tuned circuit is used to detect wobble clock inversions. The tuned circuit reacts to a wobble inversion with a change in amplitude that may be detected by a threshold detector. A bandpass tuned circuit is used to detect wobble clock inversions. The output of the bandpass tuned circuit is input to a saturating high-gain amplifier such as a comparator. The output of the saturating high-gain amplifier reacts to wobble inversions with a half-cycle that has an increased duration as compared to half-cycles without wobble inversions.

Abstract: An optical disc is manufactured under a uniform condition by forming grooves and lands on the entire surface of the disc. The optical disc is configured to obtain a reliable reproduction signal, and the grooves and lands are formed on a lead-in area, a user data area and a lead-out area of the optical disc. Since the same manufacturing condition can be adopted in mastering discs, the yield can be enhanced and the manufacturing cost can be reduced.

Abstract: In order to generate a clock signal (fT1) that is coupled to a reference signal (FBAS), especially to an analog video signal, a free-running clock pulse (fT1) is generated from a high-frequency clock pulse (f0) and the reference signal (FBAS) is digitized therewith. In addition, a second clock pulse (fT1) is generated from the high-frequency clock pulse (f0) and the phase deviation between the first clock pulse (fT2) and the second clock pulse (fT1) is determined. The digitized sampling values of the reference signal (FBAS) at the first clock frequency (fT1) are converted, according to the phase deviation determined, into corresponding digitized sampling values having the second clock frequency (fT1) and are used as a target specification for generating the second clock pulse (fT1) thus coupled to the reference signal.

Abstract: Method and device for controlling an optical recording/reproducing device, for detecting a wobble signal in advance during free running when only a focus servo is turned on, carrying out wobble PLL, detecting the present rotating speed of the optical disk from the wobble signal, and controlling the spindle to reach to a target speed quickly, thereby stabilizing the servo in advance before regular data recording/reproduction, and enhancing performance of the optical recording/reproduction device.

Abstract: A recording/reproducing apparatus and method are provided to record and reproduce data on and from a disk-shaped recording medium that has an address data area with embossed pits and a recording/reproducing area with a wobbling spiral groove. A wobble-signal processing circuit is used to extract a wobble signal from the signal the head obtains from the wobbling spiral groove and to provide the wobble signal to a PLL circuit to produce a sync signal therefrom. A pulse is produced at least during a wobble signal disturbance period occurring when switching between at least one of a recording and reproducing operation and provided to the PLL circuit in order to provide an unchanging sync signal during the wobble signal disturbance period to avoid the wobble disturbances from being carried over to the sync signal.

Abstract: An information signal is read from a recording medium to generate a reproduced signal. A sync detector detects a sync signal in the reproduced signal on a pattern search basis during operation in a direct mode. The sync detector sets a detection window and detects a sync signal in the reproduced signal in the detection window during operation in an inertia mode. A special pattern signal in the reproduced signal is detected and counted to generate a count result. The count result is reset in response to detection of a first special signal in the reproduced signal. A detection flag is generated in cases where a second special signal in the reproduced signal is detected when the count result denotes a last sector in a block of the reproduced signal. The sync detector changes its operation from the inertia mode to the direct mode when the detection flag is generated.

Abstract: An optical disk device for writing data onto an optical disk having a wobble track comprises an optical pickup for irradiating laser light of a writing power and laser light of a replaying power onto an optical disk and for converting return light from the optical disk into an electrical signal, a filter for extracting a wobble component contained in the return light signal when the laser of a writing power is irradiated, a processor for detecting the direction of track deviation based on the phase of the wobble component, and an actuator for driving the optical pickup in the width direction of the track based on the direction of the track deviation in order to control the tracking. Because the phase of the wobble component differs for a case when a light spot is deviated radially inward and for a case when a light spot is deviated radially outward, the direction of the track deviation can be detected based on the phase of the wobble component and the tracking can be controlled during data writing.

Abstract: An apparatus which records/reproduces data with respect to an optical recording medium, includes a data processing unit which detects a phase difference between a phase reference signal and a groove wobble signal detected from the optical recording medium, and compensates for the phase difference and performs a signal processing to record data on or reproduce data from the optical recording medium in response to the phase difference being equal to or greater than a predetermined reference value. By detecting a phase difference between a phase reference signal and a wobble signal and compensating for the phase difference, a recording of data on and a reproducing of data from the optical recording medium can be more accurately performed.

Abstract: A writing method for an optical disc to optimize a writing speed, wherein a spiral track on the optical disc is divided into a plurality of zones, and different CLV writing speeds are used for performing a ZCLV writing to the zones respectively. The writing method comprises steps of: setting a plurality of writing modes; storing a plurality of zone parameter sets for the writing modes respectively in a memory, wherein each of the zone parameter sets comprises dividing times for dividing the zones, and the different CLV writing speeds for the zone respectively; determining a disc type of the optical disc by a disc type determining device before the ZCLV writing is performed; selecting one of the zone parameter sets that is suitable to the disc type of the optical disc; and performing the ZCLV writing with the writing mode corresponding to the selected zone parameter set.

Abstract: An optical disc apparatus includes a recording section for recording new data on an optical disc so as to be continuous to data which is previously recorded on the optical disc; a detection section for detecting an amount of deviation between a position at which the previously recorded data is recorded and a position at which the previously recorded data should have been recorded; and an adjustment for adjusting a position at which the new data is to be recorded so that an amount of deviation between a position at which an end of the new data is to be recorded and a position at which the end of the new data should be recorded is smaller than the amount of deviation detected by the detection section.

Abstract: The present invention provides a disk driving apparatus which includes an interpolating edge circuit for generating an interpolating signal in accordance with a cycle of an edge detection signal, and a phase switching unit for performing phase switching by both the timing signal and the interpolating signal when a period for which the edge detection signal is normally generated reaches a predetermined value.

Abstract: An optical recording apparatus for recording a plurality of information units on an optical storage medium. Each of the information units includes a long run-length sync pattern. The optical recording apparatus includes a recording means for recording the plurality of information units on the optical storage medium and a sync pattern selector for determining the type of each of the long run-length sync patterns. The sync pattern selector determines at least one long run-length sync pattern as a mark when marks with run-lengths longer than a first length threshold do not appear for a time period longer than a first time threshold. The sync pattern selector determines at least one long run-length sync pattern as a space when spaces with run-lengths longer than a second length threshold do not appear for a time period longer than a second time threshold.

Abstract: A recordable or rewritable optical disk device capable of reproducing a wobble signal accurately at a high S/N ratio to thereby get address information even at a time of high-speed recording is disclosed. An optical disk is formed with wobbled guide tracks, and the light reflected from the optical disk is picked up by an optical pickup unit, which supplies corresponding electric signal to a wobble signal reproducing section. In the wobble signal reproducing section, at a time of recording, the input signal is sampled not only during a period of reproducing power and also during a period of recording power, and the two sampled signals are added to reproduce a wobble signal. The sampling during the period of recording power may be carried out within a period where the quantity of reflected light is in a stable condition after a pit is formed on the optical disk.

Abstract: A method and related circuit for synchronizing a writing clock with a wobble clock of a compact disk (CD) drive. The CD drive is capable of rotating a CD that has a data track for recording data and a wobble track. The CD drive is capable of generating the wobble clock according to movement of the wobble track while the CD is rotating. Also the CD drive is capable of writing data on the data track according to the writing clock. The method includes adjusting the frequency of the writing clock so as to synchronize the writing clock and the wobble clock.

Abstract: To resume data writing onto a disk, a recording start position detection means (19) detects a recording start position, and a synchronous setting means (20) synchronizes recording data with recorded data on a disk so that recording data successive to the recorded data on the disk can be additionally written onto the disk without a break. Data writing onto a disk is suspended until an amount of data equivalent to data writing capacity has been stored in the buffer memory (13). Data writing is resumed upon detection of the fact that an amount of data equivalent to data writing capacity has been stored in the buffer memory (13). With the above, power consumption can be reduced during a period when recording capability of a disk recording device exceeds the data transfer speed.

Abstract: An optical disc player having an optical pickup records and retrieves information on an optical disc while the optical disc is rotating. A rotation pulse is generated each time the optical disc rotates through a prescribed angle. A rotation frequency data representing a frequency of the rotation pulse is also generated. A servo processor performs servo processing for rotation control on the optical disc in accordance with the rotation frequency data. A sampling pulse generator performs computational processing on an input data signal to generate a sampling pulse. The sampling pulse generator also corrects the rotation frequency data based on a phase error between the sampling pulse and the rotation pulse to use a corrected rotation frequency data as the input data signal. Another servo processor performs servo processing for repetitive control on the optical pickup using the sampling pulse.

Abstract: A record carrier has a servo track (4) indicating an information track (9) intended for recording information blocks. The servo track (4) has a periodic variation of a physical parameter at a predetermined frequency and modulated parts for encoding position information at regular intervals. The modulated parts start with a bit sync element and are of a data type having a data bit element, or of a word sync type having a word sync element. The word sync element and the data bit element are modulated according to a same predetermined type of modulation of the periodic variation. The effective strength of a modulated element is the number of periodic variations that are substantially different and available for detection of that element. The effective strength of the word sync element and of the data bit element are equal.

Abstract: An information storage medium includes an area in which updated disc-related information and recording-related information updated with a change in at least one of a disc version number and a recording speed is recorded along with existing disc-related information and recording-related information. The existing disc-related information and recording-related information are recorded, and the updated disc-related information and recording-related information is recorded in an area in which the existing disc-related information and recording-related information is recorded. Accordingly, data can be recorded/reproduced on/from a new version of information storage medium even using an existing drive.

Abstract: An rotation speed controlling apparatus of an optical recording medium having a wobbled track includes an optical pickup for irradiating a light beam to generate a reading signal according to a wobbling shape of the track; a filter having a predetermined frequency band to pass a wobble reference frequency therethrough for extracting a wobble signal from the reading signal; a generator for generating a wobble reference signal; a detector for detecting the difference between the wobble signal frequency and the wobble reference frequency; a controller for controlling the rotation speed on the basis of the difference between the frequency of the extracted wobble signal and the wobble reference frequency; and a discriminator for discriminating that the wobble signal frequency lies outside the frequency band of the filter; wherein the controller controls the rotation speed in accordance with the detected frequency difference when the wobble signal frequency lies outside the frequency band of the filter.

Abstract: The present invention relates to method and apparatus of recording data onto a disk recording medium in zoned-CLV mode while adjusting recording speed and recording condition adequately at every speed change point between zones. The present invention detects a current recording position while recording data along a track of the disk recording medium, adjusts a recording speed and resets both a write strategy and a base B-level used for running OPC to be suitable for the adjusted recording speed. The present invention can record input data onto a writable disk with the most suitable writing condition at the highest allowable speed.

Abstract: In the context of a DVD-RAM read-type architecture in which an optical storage medium (20) makes use of an eccentric wobble (164) to attain synchronisation information, a wobble PLL (179) is held in an acquired state whenever header regions (32, 33) embossed at regular intervals across the optical storage medium (20) are detected. More specifically, large dc variations associated with voltage spikes caused by header regions (32, 33) are scaled (260) relative to a dynamically varying amplitude envelope of the extracted wobble signal (164), such as to identify a start location (300) for each header region. The wobble PLL (179) is effectively allowed to free-run and hold state during periods of header, thereby mitigating the likelihood that the wobble PLL will loose lock during the header regions.

Abstract: The frequency components of the groove wobbles of disks are extracted from push-pull signals SPP by first and second filters in a wobble detecting section. The wobble detecting section supplies to the controller the detection levels of the frequency components. The controller identifies the kind of the mounted optical disks based on the detection levels.

Abstract: The present invention has an object to stably reproduce wobble signals of all disks of CD-R/RW, DVD-R/RW and DVD-RAM by one wobble signal reproducing circuit. In the wobble signal reproducing circuit, an AGC (AUTOMATIC GAIN CONTROL) circuit for equating a push-pull circuit output of a wide range and an RF amplitude of an optical detector output of two systems obtained by push-pull, and an AGC (AUTOMATIC GAIN CONTROL) circuit for making a wobble amplitude uniform are provided with a function to hold a gain or to change over a response time constant, and at the time of reproduction of the DVD-R/RW, a land pre-pit region is detected by the push-pull output to hold AGC (AUTOMATIC GAIN CONTROL) or change over a response time constant. Besides, in an address information recording region (PID region) at the time of reproduction of the DVD-RAM, the AGC (AUTOMATIC GAIN CONTROL) is held or the response time constant is changed over.

Abstract: A tuned circuit is used to detect wobble clock inversions. The tuned circuit reacts to a wobble inversion with a change in amplitude that may be detected by a threshold detector. A bandpass tuned circuit is used to detect wobble clock inversions. The output of the bandpass tuned circuit is input to a saturating high-gain amplifier such as a comparator. The output of the saturating high-gain amplifier reacts to wobble inversions with a half-cycle that has an increased duration as compared to half-cycles without wobble inversions.

Abstract: A method of controlling a recording speed of an optical disc recording system includes detecting error information with respect to a level of a servo control signal of the optical disc recording system, and adjusting the recording speed of the optical disc recording system with reference to the error information.

Abstract: A circuit which recovers a synchronization code, and a method thereof. Where a synchronization code is not detected from an incoming bitstream, a plurality of synchronization code recovery candidate patterns are compared with an original synchronization pattern, and location data to produce an optimal synchronization pattern is determined and generated on the basis of a result of the comparison. The synchronization code is recovered to a location corresponding to the location data. Alternatively, where a synchronization code is not detected from an incoming bitstream, a plurality of synchronization code recovery candidate patterns are error-corrected, and location data to produce an optimal synchronization pattern is determined and generated on the basis of a result of the error correction. The synchronization code is recovered to a location corresponding to the location data.

Abstract: An apparatus for preventing a writing error from occurring on an optical disc. The apparatus includes an interpolation ATIP sync signal detector, a number determiner, and a writing speed adjuster. The interpolation ATIP sync signal detector receives a wobble signal from a wobble signal generator of an optical disc drive to detect an interpolation ATIP sync signal from the wobble signal. The number determiner determines a number of interpolation ATIP sync signals and generates a writing speed transformation control signal based on the determination result. The writing speed adjuster receives the writing speed transformation control signal from the number determiner to adjust a writing speed of the optical disc drive.

Abstract: A disk type record playback device having a wobble signal extracting bandpass filter for controlling a filter's center frequency according to a frequency follow-up control loop including a dummy filter identical in configuration to a filter to be controlled, and a phase comparator is capable of controlling the center frequency of the bandpass filter with satisfactory accuracy. A frequency variable lowpass filter is provided in a preceding stage of the phase comparator constituting a frequency follow-up circuit and supplies a signal obtained by eliminating harmonic components from a frequency follow-up clock signal to the phase comparator. A cutoff frequency of the lowpass filter is changed in cooperation with a center frequency of the bandpass filter, based on a signal outputted from the frequency follow-up control loop.

Abstract: A noise removal circuit of the present invention comprises a 180-degree odd multiple shifting section for outputting a 180-degree shifted signal that is phase-shifted from an input signal by an odd multiple of 180 degrees and difference output section for outputting a difference between the input signal and the 180-degree shifted signal. The noise removal circuit comprises a 360-degree shifting section for outputting a 360-degree shifted signal that is phase-shifted from an input signal by an integral multiple of 360 degrees and sum output section for outputting a sum of the input signal and the 360-degree shifted signal.