109results about "Pulse-modulation recording/reproducing" patented technology

Various embodiments of the present invention provide systems and methods for selecting between pre-coding and non-pre-coding. As an example, a data processing circuit is disclosed that includes: a first data detector circuit, a second data detector circuit, a first comparator circuit, a second comparator circuit, and a pre-code selection circuit. The first data detector circuit is selectably configurable to operate in a pre-coded state, and operable to apply a data detection algorithm on a data input to yield a first detected output. The second data detector circuit operable to apply the data detection algorithm to the data input to yield a second detected output without compensating for pre-coding. The first comparator circuit operable to compare the first detected output against a known input to yield a first comparison value, and the second comparator circuit operable to compare the second detected output against the known input to yield a second comparison value. The pre-code selection circuit is operable to determine a selectable configuration of the first data detector circuit based at least in part on the first comparison value and the second comparison value.

The present invention is directed to a method and apparatus for performing seek operations in a disk drive having a disk surface with spiral servo information written thereon. In one embodiment, a disk surface is provided with a read head associated therewith. The disk surface has spiral servo information written thereon. The read head generates a read signal envelope when reading the spiral servo information. A plurality of integration windows is provided. The plurality of integration windows have a standard interval therebetween. A position error signal is generated based upon a location of a read signal envelope within an integration window. The interval between adjacent integration windows is adjusted from the standard interval to generate a position error signal. The read head is moved in a radial direction based upon the position error signal. This process may be repeated to seek across the disk surface.

A wobble demodulator for reproducing digital information from an optical recording medium in which a track is formed in accordance with a wobble signal that is MSK-modulated so as to contain the digital information by a carrier signal with a predetermined frequency and a sine wave signal with a frequency different from that of the carrier signal, includes: a wobble signal detector for detecting a wobble signal of the track from the optical recording medium; a wobble PLL for detecting the carrier signal based on the wobble signal detected by the wobble signal detector; a multiplier for multiplying the carrier signal detected by the wobble PLL by the wobble signal detected by the wobble signal detector and outputting a multiplied output; a MSK detector for detecting a MSK modulation mark having a phase or a frequency different from that of the carrier signal, based on an integrated value obtained by integrating the multiplied output from the multiplier on a predetermined section basis; and a MSK synchronization detector for detecting a synchronization position with respect to the digital information, based on the MSK modulation mark detected by the MSK detector, wherein the MSK detector compares a continuous predetermined number of the integrated values with a first threshold value for detecting a central portion of the MSK modulation mark, a second threshold value for detecting leading and trailing edges of the MSK modulation mark, and a third threshold value for detecting non-modulated portions before and after the MSK modulation mark, and detects the MSK modulation mark based on a pattern of a comparison result.

A data storage device for retrieving data includes a controllably positionable head and a storage medium having servo information comprising a phase pattern having a first frequency and a PES pattern having a second frequency, the second frequency being different from the first frequency.

A signal is recorded on a magnetic recording medium by changing a magnetized state of a magnetic member. The magnetic recording medium includes a plurality of servo signal areas in which servo signals for controlling a position of a reproducing head are recorded with different recording frequencies in parallel to a predetermined track so that the servo signals are read by the reproducing head when the reproducing head reproduces the servo signals along the predetermined track.

There is disclosed a recording method for performing a DSV control while recording a recording signal generated by inserting a synchronous signal for decoding reproduction data into every predetermined number of code words in a code word string satisfying a predetermined run length restriction rule and to be outputted into a recording medium, when a plurality of coding tables are used to convert an input data word of p-bits to a code word of q-bits (q>p), and the code word string obtained by directly coupling the code words is recorded and reproduced in a recording medium such as an optical disk and magnetic disk, or transmitted via a transmitting portion, wherein the p-bits are 8 bits, the q-bits are 15 bits, and the predetermined run length restriction rule stipulates that a minimum run length of the signal obtained by NRZI-converting the code word excluding the synchronous signal is 3T, and a maximum run length is any one of 11T, 12T, 13T, and 14T.

A 6-bit output code word is generated in response to every 4-bit input code word by referring to a set of encoding tables. The encoding tables contain output code words assigned to input code words, and contain encoding-table designation information accompanying each output code word. The encoding-table designation information designates an encoding table among the encoding tables which is used next to generate an output code word immediately following the output code word accompanied with the encoding-table designation information. The generated output code words are sequentially connected into a sequence which follows run length limiting rules. The run length limiting rules are changed between RLL(1, 7) and RLL(1, 8) in response to auxiliary information to superimpose the auxiliary information on the sequence of the generated output code words.

Methods are provided for improving servo-demodulation robustness, especially when used with a disk having zone bit recorded servo wedges. A servo address mark (SAM) pattern is searched for, within a servo wedge, at a first nominal frequency useful for searching for the SAM pattern if the servo wedge is within a first zone. The SAM pattern is also searched for, within the same servo wedge, at a second nominal frequency useful for searching for the SAM pattern if the servo wedge is within the second zone. A determination of which one of two zones a head is reading, can then based at least in part on which nominal frequency was used to successfully detect the SAM pattern.

An apparatus for providing data dependent detection in a data read channel is disclosed. Parameters in a read channel are dynamically adjusted according to data dependent noise. For example, a comparison in an add-compare-select (ACS) unit of a Viterbi decoder may be adjusted or offset terms in error event filters may be biased to choose a Viterbi sequence with more transitions or to compensate for polarity dependent noise.

An apparatus comprises a data storage medium having a plurality of servo sectors and a plurality of data sectors, wherein each of the servo sectors includes a phase locked loop field and a track identification field, a controller for controlling the position of a recording head with respect to the data storage medium, and a servo demodulator for recovering timing information from both the phase locked loop field and the track identification field, and for producing a timing estimate. The method performed by the apparatus is also included.

Apparatuses and methods for detecting reference marks on magnetic data storage mediums are described herein. In one variation, the apparatus comprises a magnetic servo position demodulator operable to extract information from the magnetic data storage medium utilizing Partial Response / Maximum Likelihood (PRML) technique. Synchronization marks stored within the PRML channel is then detected utilizing a digital filter. For each of the detected synchronization mark, a further refined position of the synchronization mark can be determined utilizing a mathematical prediction model.

Servo demodulation is performed by appropriately compensating for demodulation errors caused by fluctuation of the replayed signal amplitude of a phase servo pattern. A servo demodulating circuit comprises single waveform sampling means for reading into a register a single waveform of a servo burst signal included in a phase servo signal based on a sampling clock synchronized by clock synchronization means, single waveform digitizing means for calculating an amplitude value of the single waveform of the servo burst signal from peak and bottom of the single waveform of the servo burst signal read into the register, and for standardizing a value of the register based on an amplitude value of the single waveform of the servo burst signal, and phase information calculation means for calculating phase information of the single waveform of the servo burst signal based on the value of the register standardized by the waveform digitizing means.

Multiple servo sensors are laterally displaced over a distance less than the transverse width of timing based servo track laterally extending transitions. The servo sensors are configured to sense the transitions, and servo detection logic detects the relative timings of the laterally extending transitions sensed by the laterally displaced servo sensors as the magnetic tape is moved in the longitudinal direction. Logic is configured to determine from the relative timings of the sensed transitions for at least one known set of laterally extending transitions having differing slants, the lateral position of a servo sensor by employing the relative timing detected from one servo sensor and the relative timing detected from another servo sensor, or determine the longitudinal velocity of the magnetic tape by determining the difference between the relative timing detected from one servo sensor and the relative timing detected from another servo sensor.

An optical information recording medium is provided. This medium at least stores information that indicates a maximum recording linear velocity Vh. The medium comprises a substrate having a concentric circular guide groove. This guide grove has land portions and groves portions. At least a phase change type recording layer is formed on the substrate. The recording layer has such a composition and thickness that a dislocation linear velocity V satisfies the relation V≧Vh×0.85.

A magnetic data read circuit includes a differentiation circuit and an integration circuit which are individually connected to a magnetic head, and a means of read judgment for pass / fail judgment on reading operation of magnetic data detected at the magnetic head. The read judgment means has first and second storage sections in which data relating to an output signal of the differentiation circuit and the integration circuit, respectively, are stored. The read judgment section obtains data from at least one of the first storage section and the second storage section and makes a pass / fail judgment on reading operation of the magnetic data. Such a magnetic data read circuit improves accuracy of reading magnetic data stored in a magnetic recording medium from a single transfer of the magnetic recording medium data.

An audio apparatus comprising a modulator 12 for modulating a first ultrasonic signal 29 with an audio signal to provide a second ultrasonic signal 30; a transducer 15 for converting the second ultrasonic signal 30 into an ultrasonic pressure wave for transmission into a non-linear medium to allow demodulation of the ultrasonic pressure wave and thereby generate an audio pressure wave representative of the audio signal 29, processing means 11 for modifying the audio signal to compensate for the demodulating properties of the non-linear medium; and means 8 for modifying the audio signal to compensate for the conversion characteristics of the transducer 15.

A method and apparatus to control an operating clock frequency of a hard disk drive. The method includes analyzing a command workload, and changing the operating clock frequency of the hard disk drive based on an analysis result. Alternatively, the method includes measuring a time taken to receive a predetermined number of write / read commands and controlling the operating clock frequency of the hard disk drive based on a result of a comparison of the measured time with at least one reference value. An operating clock frequency control block included in the hard disk drive executes the method.

Various embodiments of the present invention provide systems and methods for synchronizing data processing. As one example, a method for synchronizing data processing is disclosed that includes receiving a data input, and sampling the data input at a sample period to generate a sample set. A first pattern is received and a first periodic boundary associated with the first pattern is identified. In one particular case, the first pattern is a preamble pattern included as sector data on a storage medium, and the first periodic boundary is a 4T boundary. Further, a second pattern is detected in the sample that is used to establish a second periodic boundary. In one particular case, the second pattern is a SAM pattern included as sector data on a storage medium, and the second periodic boundary is a 1T boundary. Based at least in part on the first periodic boundary and the second periodic boundary, a time to transmit or assert a data-found signal is determined.

A new technique for Hard Disk Drive (HDD) servo-burst demodulation is provided. A 4-samples per dibit Discrete Fourier Transform (DFT) amplitude estimation is used to calculate the read-head servo-position error signal. Comparatively, the conventional method of burst demodulation—called burst integration—typically uses more than 8 samples / dibit. Consequently, the new 4-samples / dibit DFT burst-demodulation scheme requires fewer samples per dibit than does burst integration, thus reducing the disk space occupied by the burst data while increasing the performance as compared to burst integration. Furthermore, the DFT scheme does not require the samples to be synchronized to any particular points of the servo burst, and can include an averaging algorithm that further improves performance for a given Signal to Noise Ratio (SNR). Moreover, the same sample-clocking circuit that detects the Gray Code servo information can also implement the DFT burst-demodulation scheme to demodulate the servo burst.

A patterned recording media comprises a segment and a null pattern formed in the segment. The segment comprises first and second rows of discrete magnetic elements separated by a non-magnetic material, and a row of non-magnetic material positioned between the first and second rows. The null pattern comprises consecutive groups of the discrete magnetic elements in the first and second rows of the segment. Each group in the first row has a magnetic polarity that is opposite the magnetic polarity of adjoining groups in the first row. Each group in the second row has a magnetic polarity that is opposite the magnetic polarity of adjoining groups in the second row.

A method and apparatus for outputting an audio signal and a method of adjusting the volume of an audio signal are provided. An embodiment of the present invention provides a method for outputting an audio signal that includes: (a) determining an output level of a modulated signal to be outputted for each respective frequency band by using a hearing threshold measured for the respective frequency band; and (b) outputting the modulated signal and an audio signal simultaneously. An embodiment of the present invention can improve hearing ability by outputting an audio signal and a modulated signal together. Also, according to an embodiment of the present invention, a user can use visual signals to personally set the output level of audio signals that is optimal for each frequency band in accordance with changes in the user's dynamic hearing threshold for each respective frequency band, even while listening to audio signals of which the output level for each frequency band was determined previously.

A method of encoding and decoding data involving the simultaneous application of pulse width modulation and pulse position modulation systems to data intended for storage on a magnetic disk medium.

An audio playback device having a function for adjusting a playback speed, and a method thereof includes, in the audio playback device, stored audio data is decoded and converted into an audio stream in a PCM format, and the audio stream is divided into a high frequency band and a low frequency band at cut-off frequency. The audio stream of the high frequency band is signal-processed using an overlap add (OLA) algorithm, and the audio stream of the low frequency band is down-sampled and signal-processed using a synchronized overlap and add (SOLA) algorithm. Accordingly, calculation time of the stream processor 130 is minimized so that a TSM function is efficiently implemented.

Various embodiments of the present invention provide systems and methods for write pre-compensation. For example, various embodiments of the present invention provide systems for on-the-fly estimation of write pre-compensation values. Such systems include a magnetic storage medium, a read / write head assembly disposed in relation to the magnetic storage medium, and an analog to digital converter that receives an analog signal from the read / write head assembly corresponding to a data set stored on the magnetic storage medium and provides a series of digital samples corresponding to the data set. The storage devices further include a read data processing circuit that receives the same series of digital samples and provides a user data output, and a pre-compensation value calculation circuit that receives the series of digital samples and provides an updated write pre-compensation value.

Embodiments in accordance with the present invention provide a magnetic disk drive capable of achieving error recovery stably in a simple configuration in the event of thermal asperity (TA) and minimizing the error recovery time required, and a method for controlling the disk drive. According to one embodiment, if TA occurs, a cutoff frequency of a high-pass filter to which a data read signal is input is first increased and a loop gain of a low-order finite impulse response (FIR) filter connected in series to an FIR filter is also increased as high as possible. Next, a Viterbi decoder to which a signal is input from the low-order FIR filter provides feedback to the low-order FIR filter so that an input signal error becomes a minimum. Tap coefficients of the low-order FIR filter are thus optimized.

A method and apparatus demodulate pre-formatted information embedded in an optical recording medium. The demodulation includes (a) receiving a wobble signal representing data symbols frequency-modulated on a carrier frequency, (b) generating a phase delta signal representing a phase difference between the wobble signal and a corresponding locked signal having the carrier frequency, (c) first sampling the phase delta signal at a data sampling interval to produce first values, (d) second sampling the phase delta signal at each halfway of the data sampling interval to generate second values, (e) determining, based on a difference between two successive second values, if the first sampling is performed at timing corresponding to an end of each data symbol, and (e) adjusting sampling timing of the first sampling towards the timing corresponding to each end of the data symbols, if the sampling timing does not corresponds to the end of each data symbol.