Abstract: An optical pickup inspection device 3 sends to an actuator drive circuit 16 a command for changing defocus offset amount to set defocus offset amounts, and calculates jitter values for each of the defocus offset amounts based on a reproduction signal from a reproduction signal generation circuit 14. Then, the device 3 determines a quadric approximating curve of jitter values relative to the defocus offset amounts and calculates a correlation coefficient R2 of the quadric approximating curve and measured values. If the correlation coefficient R2 is lower than a threshold value, the setting of defocus offset amounts and the calculation of jitter values are executed once again, otherwise, a defocus offset amount corresponding to a bottom value of jitter in the quadric approximating curve is determined as an optimum value of the defocus offset amount. Thus, a less-error, high-accuracy optimum value of the defocus offset amount can be obtained.

Abstract: An apparatus and method to write/reproduce data to/from an optical disc, which are capable of preventing an error from occurring at the time of examination of a writing strategy and searching for an optimum writing condition for a short period of time, by examining the writing strategy after adjusting a focus in a test region, in order to set a writing condition at the time of writing data. The apparatus to write/reproduce data to/from an optical disc includes a matrix jitter measuring unit which measures length errors and jitters of edges of a mark and a space of a written data pattern from an RF signal generated at the time of reproduction of the optical disc; and a CPU which extracts at least one of the RF signal, a jitter and an error rate, controls a focus bias, and performs an optimum power calibration (OPC) for searching for optimum power of laser.

Abstract: In order to ensure recording quality while suppressing the adverse effects due to performance variations among apparatuses and disc radial positions on an optical disc, an optical disc apparatus according to the present invention performs, at the time of data recording, the steps of: acquiring a jitter value and ? value from a reproduced signal based on laser light reflected from the optical disc in relation to a disc radial position; learning a ? value when the acquired jitter value is a minimum as a target ? value; and, if a jitter value acquired thereafter is larger than the minimum jitter value by a preset reference value or above, correcting recording power based on the magnitude relation and the difference between the ? value associated with the acquired jitter value and the target ? value or performing trial record processing.

Abstract: The present invention relates to a method for checking the quality of a recording on a disk intended to be read with a first wavelength and intended to be recorded with a second wavelength, directly with the second wavelength used by the recording system. According to the invention, the method uses a modified jitter definition when a jitter value of recorded information is measured using light of the first wavelength. A special equalizer takes account of a required asymmetry.

Abstract: An optical disk writing apparatus enhances writing accuracy by writing first data (e.g., test data) that encodes a first writing strategy within first patterns on an optical disk, in response to a first writing signal. A reproducing signal is generated in response to reading the first data from the optical disk. Variations between leading and trailing edges of the first writing signal and leading and trailing edges of the reproducing signal are detected. A correction value is determined using a jitter evaluation function to evaluate the detected variations. From these operations, a second writing strategy is determined using the correction value to modify the first writing strategy. Thereafter, second data (e.g., actual data) is written, which encodes the second writing strategy within second patterns on the optical disk.

Abstract: An optical disc drive having an optical pickup head emitting a light beam to an optical storage medium, detecting the light beam reflected from the optical storage medium, and outputting a signal based on the received reflected light, having a jitter measuring unit measuring jitter in signals output from the optical pickup head and having an evaluation unit determining from the measured jitter if the optical storage medium is good or defective. The jitter measuring unit measures jitter in a train of 3T or longer marks or spaces from an optical storage medium to which digital information is recorded as a train of marks or spaces of length kT based on a period T and an integer k of two or more.

Abstract: An optical data carrier includes at least one session in which one or more tracks are stored, wherein each session includes a plurality of data frames, and wherein each data frame includes controlling data and content data coded in a first format. In place of at least part of at least one bit sequence which would be included within said content data and which would correspond to constant data with respect to a second format into which said content data would be converted during a reading process, if said one or more tracks had been transferred onto said optical data carrier in accordance with a predetermined CD standard, the at least part of the at least one bit sequence is represented by a bit sequence which does not correspond to constant data with respect to said second format.

Abstract: An optical disc signal processing apparatus comprising: a binarizing circuit configured to compare a level of an RF (Radio Frequency) signal obtained by photoelectrically converting a reflected light of a laser beam applied to an optical disc and a level of a DC signal, to output a binarized signal for reproducing information recorded on the optical disc, a level of the DC signal being adjusted to a level at which jitter included in the binarized signal is minimized.

Abstract: When performing writing and/or reading of information to/from an optical disk provided with a wobble including time axis information, an occurrence of a reading error of the time axis information from the wobble is suppressed so that disabled reading of information from the optical disk and an occurrence of a writing error can be prevented. Evaluated parameters such as a CRC error rate of an ATIP signal, an FMDT jitter amount and a phase error between an ATIP synchronization signal and a frame synchronization signal of writing data are evaluated based on a range of set values. When the evaluated parameter is deviated from the range of set values, writing and reading speeds are changed, thereby increasing the reading accuracy of the wobble signal.

Abstract: A jitter counter according to the present invention is connected to a PLL circuit for generating a clock signal, which is necessary for signal processing, from a binary signal, and counts jitters of the binary signal.

Abstract: To provide an optical disk and an optical disk reproducing device capable of preventing sub information from being illegally copied and altered. An optical disk includes an optical disk substrate preliminarily provided with concave/convex recording marks in order to record the main information; and a reflection film which covers the optical disk substrate and of which the reflection coefficient is changed by irradiating laser light at or above a certain intensity. The reflection film is preliminarily provided with additional marks for recording the sub information by changing the reflection coefficient of the reflection film on a region where the concave/convex recording marks are formed and the sub information is recorded for every predetermined recording unit for recording the main information. The laser light at or above the certain intensity is irradiated onto the region where the sub information is recorded to reproduce the main information and delete the sub information.

Abstract: An optical disc drive having an optical pickup head emitting a light beam to an optical storage medium, detecting the light beam reflected from the optical storage medium, and outputting a signal based on the received reflected light, having a jitter measuring unit measuring jitter in signals output from the optical pickup head and having an evaluation unit determining from the measured jitter if the optical storage medium is good or defective. The jitter measuring unit measures jitter in a train of 3T or longer marks or spaces from an optical storage medium to which digital information is recorded as a train of marks or spaces of length kT based on a period T and an integer k of two or more.

Abstract: While reproducing information on an optical disc, an optical disc apparatus varies a focus balance value in both positive and negative directions from a currently set value thereof by ±a which will not affect reproduction operation, measures jitter levels c and d of a reproduced signal when the focus balance value is varied in the positive and negative directions, and calculates a difference e=c?d between the measured jitter levels. If this difference e exceeds a threshold value f, the optical disc apparatus varies the focus balance value by a specified amount g in a direction in which the difference e approaches 0, thereby updating the current focus balance value.

Abstract: An apparatus and method for testing mechanical endurance of a surface of an optical disc is disclosed, which includes a rotating plate on which the optical disc is fixed to generate scratch thereon, and rotating the fixed optical disc; and a plurality of abrasion wheels disposed in perpendicular to the rotating plate, and being in contact with the surface of the optical disc, to generate the scratch on the surface of the optical disc, wherein, the scratches generate when the optical disc rotates a predetermined turn, e.g. below ten turns for applying a predetermined load generated from the abrasion wheel on the optical disc.

Abstract: An optical disk apparatus includes a signal detection unit which detects a signal corresponding to a wobbling guide groove formed on an optical disk, a timing signal generating unit which generates first and second timing signals in accordance with an amplitude level of the signal detected, a photodetector which detects reflective light from the optical disk, and a wobble signal generating unit which outputs as a wobble signal a signal which is amplified with a low gain amount by the first timing signal in a case where an arithmetic signal, which is generated for the wobble signal on the basis of a signal detected by the photodetector, is at a high amplification level, and outputs as the wobble signal a signal which is amplified with a high gain amount by the second timing signal in a case where the arithmetic signal is at a low amplification level.

Abstract: An optical disk recording method for recording predetermined data on an optical disk on the basis of a first reference clock signal used for recording, the optical disk including a groove track having a wobble signal recorded thereon and a land track having a land pre-pit carrying track position information, the first reference clock signal being generated on the basis of the wobble signal reproduced from the optical disk, includes the steps of reproducing a pre-pit signal from the optical disk; generating a second reference clock signal from the pre-pit signal; detecting an amount of phase shift of the first reference clock signal using the second reference clock signal; and correcting the first reference clock signal on the basis of an average value of the detected amount of phase shift.

Abstract: According to an embodiment, an apparatus for recording data in a recording medium, includes a reading/recording unit recording or reading data on or from the recording medium, the read data including a position information, the position information indicating a last recorded position and a recordable position for new data to be recorded; and a controller examining whether or not an area corresponding to the recordable position has an already recorded data, and determining whether to change the recordable position to another position for recording the new data based on the examination result, the another position being physically separated from the recordable position indicated by the read data recording information, wherein the controller identifies another position for recording the new data if the area has the already recorded data.

Abstract: A system for increasing storage capacity of an optical medium includes a demodulator module and a writing module. The demodulator module demodulates a wobble signal having a wobble period of N channel bits, has a demodulating period of M channel bits, and generates a phase error signal, where N and M are integers greater than 1, and M is greater than N. The writing module writes M bits on the optical medium during the wobble period of the N channel bits based on the phase error signal.

Abstract: A method for automatically calibrating an output power of an optical pick-up head is provided. First, an optical disc is provided, wherein a relationship between the output power for writing the optical disc and a specific parameter corresponding thereto is defined as a first function. Next, the optical pick-up head is controlled to perform a writing operation on the optical disc according to an instruction value, and obtain the specific parameter corresponding to the instruction value. Next, the output power corresponding to the instruction value is obtained according to the first function and the specific parameter. Next, the instruction value is adjusted according to the instruction value and the output power, and the output power of the optical pick-up head is calibrated according to the adjusted instruction value.

Abstract: A protective system and method for data write of an optical disk drive, which produces a pseudo synchronization signal for the optical disk drive to perform a write operation on an optical disk. First, a write target sector is determined and a current sector of the optical disk is monitored. Next, it is determined whether a wobble synchronization signal is possibly extracted from the optical disk; if not, the pseudo synchronization signal is produced. Finally, the optical drive is driven to perform the write operation on the optical disk.

Abstract: An embodiment of the present invention provides a phase difference detection circuit for detecting a phase difference between input data and an input clock generated based on the input data, including: an input data edge position detecting part detecting an edge position of the input data based on an N-phase clock obtained by dividing a predetermined period into N areas (N is an integer of 2 or more); an input clock edge position detecting part detecting an edge position of the input clock based on the input clock and the N-phase clock; and a phase difference detecting part detecting the phase difference between the input data and the input clock based on the edge position of the input data and an edge position of the input clock.

Abstract: A record and reproduction apparatus includes: a CPU; a memory; a recording medium control unit configured to read out data from a recording medium; a reproduction buffer configured to temporarily store stream data such as an image and an audio out of the data read by the recording medium control unit; a reproduction processing unit configured to decode and reproduce the stream data temporarily stored in the reproduction buffer; and an access control unit configured to control the timing by which the access control unit switches between access to the memory and access to the reproduction buffer so that the reproduction processing does not break off during reproduction of the stream data while supervising the state of the reproduction buffer, and to manage the memory and the recording medium control unit in each transaction.

Abstract: A method and apparatus for recording data at specific locations on a DVD includes selectively detecting the occurrence of wobble sync during a window computed from previous occurrences of wobble sync and eight-to-fourteen modulation sync. The method and apparatus also uses a phase-locked loop to recover the wobble signal, including wobble sync, and computes phase drift between wobble sync and eight-to-fourteen modulation sync and applies a compensation profile, compatible with a read clock phase-locked loop, to the wobble phase-locked loop.

Abstract: A recording apparatus includes: a first strategy calculating device (SCD) for calculating a first optimum strategy allowing jitter recorded at a first speed to satisfy a desired condition by adjusting a first standard strategy; a second SCD for calculating a second standard strategy at a second speed by performing clock cycle conversion according to a difference between the first and second speeds on the first standard strategy; a second power calculating device for calculating a second optimum power used at the second speed; a third SCD for calculating a second optimum strategy allowing jitter recorded at the second speed to satisfy a desired condition, by adjusting the second standard strategy; and a fourth SCD for calculating a third optimum strategy at a third speed, based on each of a difference between the first standard and optimum strategies and a difference between the second standard and optimum strategies.

Abstract: Based on actual recording power information obtained during test writing, a recording power is efficiently controlled with high accuracy during actual recording. An information recording apparatus irradiates a laser light onto an information recording medium such as an optical disc to record data and reproduce the recorded data. In recording actual data such as data designated by a user, the information recording apparatus temporarily stops recording at the time when predetermined amount of data is recorded, and confirms recording quality. Namely, the apparatus reproduces the recorded data and determines the recording quality based on the reproduced data. When it is determined that the recording quality is within an appropriate range, the recording of the actual data is continued at the recording power.

Abstract: A PLL circuit includes a wobbling detector for detecting a wobbling signal based on reflection light of an optical disk having a wobbled track, and a VCO that an oscillation frequency of its output varies according to its input. The PLL circuit controls the VCO based on a phase error between the output of the wobbling signal and the output of the VCO. In the PLL circuit, the phase error is detected by executing an arithmetic operation to the delta-sigma modulated wobbling signal at a predetermined clock and the output of the VCO.

Abstract: An apparatus and method for demodulating an input signal modulated from a reference signal and a data signal are disclosed. The apparatus includes a determining unit, a first calculating unit, and a comparing unit. The determining unit is utilized for determining a plurality of first calculating timings of changing different calculating modes according to the input signal. The first calculating unit is coupled to the determining unit and utilized for generating a first calculating result of the input signal according to the first calculating timings and the calculating modes thereof. The comparing unit is coupled to the first calculating unit and utilized for generating a comparing result according to the first calculating result of the input signal and a threshold setting, and for outputting a demodulated data of the input signal according to the comparing result.

Abstract: An enhanced write splice for optical recording channels is disclosed. Optical control circuitry locks to previously-written data and determines the estimated write splice location. A training sequence is written to the optical medium at a location based on the estimated write splice location. The phase offset is then estimated by reading the training sequence. A new write splice location may then be calculated compensating for the phase offset estimate. Finally, the new data to be spliced may be written or overwritten to the channel at the new write splice location.

Abstract: Calibration methods are provided for determining servo parameters to enhance an optical drive in reading and writing a blank optical disc. First, test data is written on the blank disc with various writing parameters. Second, the written test data is read from the optical disc with various reading parameters. A plurality of quality measures are obtained, each corresponds to a specific combination of the writing parameter and the reading parameter. An optimal writing parameter and an optimal reading parameter are determined by comparing the quality measures with respect to both the reading and writing parameters respectively.

Abstract: An aspect of the present invention provides an apparatus for reproducing encoded data that includes a data analyzer configured to analyze an encode method of the encoded data to reproduce, a controller configured to receive a seek command and a target time to seek, calculate a seek controlling bit rate according to a part of the encoded data, and compute, according to the calculated seek controlling bit rate, a data size corresponding to the target time to seek, and a decoder configured to skip the encoded data for the computed data size by the controller and decode, based on the analyzed encode method by the data analyzer, the encoded data after the end of the skipped part thereof.

Abstract: An optical disc recording and reproducing apparatus for recording and reproducing data in and from an optical disc by the use of the optical disc as a recording medium, comprises analog processing means including a binarization unit for subjecting a signal read from the optical disc to binarization and a servo unit for controlling recording and reproducing a signal in and from the optical disc; synchronous clock generating means for generating a synchronous clock signal which is synchronized with the signal read from the optical disc; address detecting means for detecting address information indicating a physical position on the optical disc based on the signal read from the optical disc, and outputting a signal indicating the address information and a signal indicating that the address has been detected when the address information has been detected; a sector counter for holding a sector count value of a sector as a recording unit on the optical disc, and updating the sector count value according to the sync

Abstract: The present invention is aimed at providing an optical disc device and a recording condition setting method which can automatically determine an optical recording condition to an optical disc, and the optical disc device comprises an optical pickup which records data on a disc; a data encoder which modulates data to be recorded; a recording timing setting means which sets a timing of recording the data on the disc; a phase error detection means which measures an error amount of a mark recorded on the disc from a position where the mark should be properly located; an error convergence means which calculates error information indicating an optimum position of the mark; a recording timing calculation means which calculates a correction value of the recording timing to be set on the recording timing setting means, based on the error information; and a control means which feedbacks an output of the recording timing calculation means to the recording timing setting means, thereby to optimize the recording timing.

Abstract: It is an object of the present invention to provide a recording condition closer to an optimum even for a medium unknown to a drive, and more particularly to provide a method especially effective when applied to code identification methods, such as PRML, wherein codes are identified based on amplitude information of an RF signal. In order to accomplish the object, an RF signal received from a photo-receiving part 108 of a pickup is converted into sampling data by an A/D converter 300, and a Viterbi decoder 302 performs code determination using the sampling data. Codes included in a reproduction signal are then determined by synchronizing recording pulses with the reproduction signal using the result of the code determination. Then, the result is used to specify a part to be detected in the codes, and finally an amplitude of the specified part is detected.

Abstract: An optical disk drive for scanning an optical disk having a wobbled groove and a land portion separating adjacent parts of the groove. The optical disk drive has a beam generator for generating a read beam and directing the read beam to the optical disk, a sensor for sensing a reflected beam produced by the optical disk upon receiving the read beam and for producing a sensor output signal with a sensor output signal amplitude, and an envelope analyzer to receive the sensor output signal from the sensor, to analyze an envelope (WS1e, WS2e) of the sensor output signal amplitude, and to derive from a variation of the envelope (WS1e, WS2e) as a function of time an indicator indicating whether the read beam is directed to the groove or to the land portion.

Abstract: A clock signal generator according to the present invention includes: a wobble phase error detecting section for detecting a wobble phase error that is a difference in phase between a wobble signal, representing a wobbled shape of a track on an optical disk medium, and a clock signal; a data phase error detecting section for detecting a data phase error that is a difference in phase between a data signal, representing data that has been written on the optical disk medium, and the clock signal; a frequency control section for generating a frequency control signal to control the frequency of the clock signal based on the wobble phase error and the data phase error; and a clock oscillation section for generating the clock signal with its frequency controlled in accordance with the frequency control signal.

Abstract: In an optical disk drive that is equipped with a binarization circuit by the PRML method and carries out record/reproduction at a speed higher than a standard speed, to realize reproduction compatibility between the drive and another optical disk drive by the ordinarily adopted direct slice method. It can be realized by applying verification judgment equivalent to reproduction at a standard speed in accordance with a reproduction speed. More specifically, it is realized by counting 2 T data number by the direct slice method, using a Viterbi decoder that validates a run length shorter than the minimum run length, and adopting other measures. A higher record/reproduction speed is realized while reproduction compatibility, which is an important original function of an interchangeable optical disk, is secured.

Abstract: A method of optimizing the write power for recording marks in an information layer of a record carrier by irradiating the information layer with a (pulsed) radiation beam. The method includes recording a pattern of test marks including short marks having a predetermined short nominal runlength onto the record carrier by applying at least three different write powers; measuring the runlengths of the recorded short marks obtained by applying the at least three different write powers; and determining an optimum write power based of the deviations of the measured runlengths from the nominal runlength of said short marks.

Abstract: An optical disc apparatus includes an emitter which emits a laser beam to a optical disc, a divided photodetector including a first divided portion and a second divided portion disposed in a light path of the reflected beam from the optical disc, and producing a first photodetector signal and a second photodetector signal, a phase difference detector which produces a phase difference signal from a phase difference between the first and the second photodetector signals, an integrator which produces a integral signal from a integration of the phase difference signal, a tracking controller configure to perform tracking control based on the integral signal, and a limiter which limits a signal to be supplied from the divided photodetector to the phase difference detector or a signal to be supplied from the phase difference detector to the integrator based on a detection status of a signal detected by the divided photodetector.

Abstract: An apparatus for and a method of detecting a wobble signal in accordance with a time shift includes comparing a basic wobble signal with reference levels to detect pulses representing the time shift in an analog fashion, and digitally determining a code value for the basic wobble signal on the basis of the widths of the pulses using a channel clock signal and a wobble clock signal. The determined code value is accumulated and serves as a basis on which final wobble data is produced.

Abstract: An address detection circuit includes a correction signal generator that generates a plurality of timing correction signals based on an ADIP (Address In Pre-groove) signal that is read out from a wobble of an optical disk, the timing correction signals having different cycles with each other, a correction signal selector that selects one of the timing correction signals generated by the correction signal generator and outputs the selected signal, and a timing corrector that outputs a data address detected based on a data signal that is read out from a data track of the optical disk at a timing in accordance with the timing correction signal transmitted from the correction signal selector.

Abstract: An optical disc reproducing apparatus has a function of setting a cutoff frequency and a boost amount of a read out signal from an optical disc and performing equalizer adjustment, and includes a system controller for searching for an optimal jitter value by simultaneously changing a cutoff frequency and a boost amount to thereby set positions of jitter measuring points determined on a coordinate plane whose abscissas represent cutoff frequencies and whose ordinates represent boost amounts, and by moving the measuring points.

Abstract: A method utilized for detecting a physical mark in a signal read from an optical disc, including: generating a matching signal capable of being utilized to identify the physical mark according to a reference clock and a wobble clock; generating a comparison signal by comparing the matching signal and a wobble data signal; determining whether a period of which the level of the comparison signal surpass a predetermined level within a predetermined period is greater than a threshold or not; and if the period greater than the threshold, generating an indication signal corresponding to the location of the physical mark. Wherein the wobble data signal and the wobble clock is generated according to the read back signal.

Abstract: An information reproduction device capable of a more appropriate frequency monitoring of a read clock, as compared to conventional devices, is realized.

Abstract: There is provided an optical disc device which can evaluate in a short time as to whether an optical disc is recorded with satisfying the standard or not. An optical disc device for measuring a recording deviation amount of data recorded on an optical disc on which physical addresses are previously provided, includes an address detection circuit which detects the physical address and outputs a physical address detection signal, a timer which is operated in synchronization with reproduced data from the optical disc, a recording deviation amount measurement circuit which measures the recording deviation amount of data recorded on the optical disc by using the physical address detection signal and the count value of the timer, a memory which stores the measured recording deviation amount, and a data transfer circuit which transfers the recording deviation amount to the memory.

Abstract: An information recording system for recording information on an optical disc using a reference clock signal generated based on a push-pull signal including a wobble frequency component, the system includes an amplitude obtaining unit for obtaining an amplitude value of the push-pull signal, a threshold calculation unit for calculating a displacement threshold of the push-pull signal based on the amplitude value obtained by the amplitude obtaining unit, and a noise reduction unit for generating a corrected push-pull signal by correcting the push-pull signal such that a displacement exceeding the displacement threshold is reduced. The reference clock signal is generated based on the corrected push-pull signal generated by the noise reduction unit.

Abstract: An apparatus and method for testing mechanical endurance of a surface of an optical disc is disclosed, which includes a rotating plate on which the optical disc is fixed to generate scratch thereon, and rotating the fixed optical disc; and a plurality of abrasion wheels disposed in perpendicular to the rotating plate, and being in contact with the surface of the optical disc, to generate the scratch on the surface of the optical disc, wherein, the scratches generate when the optical disc rotates a predetermined turn, e.g. below ten turns for applying a predetermined load generated from the abrasion wheel on the optical disc.

Abstract: An optical disc drive having an optical pickup head emitting a light beam to an optical storage medium, detecting the light beam reflected from the optical storage medium, and outputting a signal based on the received reflected light, having a jitter measuring unit measuring jitter in signals output from the optical pickup head and having an evaluation unit determining from the measured jitter if the optical storage medium is good or defective. The jitter measuring unit measures jitter in a train of 3T or longer marks or spaces from an optical storage medium to which digital information is recorded as a train of marks or spaces of length kT based on a period T and an integer k of two or more.

Abstract: In an apparatus and method for checking a network synchronization clock signal in a communication system, the apparatus generates a divided clock signal which is the same as an externally inputted network synchronization clock signal, compares the value of one period of the network synchronization clock signal to the value of one period of the divided clock signal, and determines whether the network synchronization clock signal is normal or not. Thus, the reliability of an operation of checking the network synchronization clock signal is enhanced.

Abstract: A fast optimum power control method is disclosed, with a laser power level being adjusted in a predetermined sequence at an ADIP/ATIP frame of an optical recording medium. Jitter is measured at each ADIP/ATIP frame in order to obtain an average jitter value for that particular frame, and hence power level.

Abstract: A wobble signal for an optical storage device is generated by adjusting a center frequency (?0) of a band pass filter based on an expected frequency of the wobble signal and/or an estimated position of a pick-up apparatus and filtering an input signal corresponding to the wobble signal from the pick-up apparatus with the adjusted band pass filter to provide the wobble signal. Adjusting the center frequency (?0) of the band pass filter may also be based on a measured phase change of the band pass filter. Systems for generating a wobble signal, wobble signal detection circuits and optical storage devices are also provided.