224results about "Signal processing to reduce distortions" patented technology

A write-once optical recording medium, and a method and apparatus for recording management information on the recording medium are provided. The method includes recording, in a temporary defect management area (TDMA), management information produced while the recording medium is in use, and transferring and recording the latest management information of the TDMA in a final defect management area (DMA) of the recording medium at a DMA fill-in stage of the recording medium.

A recording medium of writable once type, and a method and apparatus for managing a defective area on the recording medium are provided. The method includes detecting an existence of a defective area within a data area of the recording medium once data are written onto the data area in a data writing operation; writing data written in the defective area onto a spare area of the data area if the defective area is detected; writing temporary management information pertaining to the defective area, onto a temporary management area on the recording medium; and writing access information for accessing the temporary management information, onto a reserved area on the recording medium.

Various embodiments of the present invention are related to methods and apparatuses for decoding data, and more particularly to methods and apparatuses for multi-level layered LDPC decoding with out-of-order processing.

A magnetic recording and reproducing apparatus is disclosed which includes: a recording device configured to record with a write head a plurality of tracks constituting a unit of signal processing for data detection, to magnetic recording media; a reproduction device configured to reproduce with a read head a plurality of reproduction signals concurrently from the plurality of tracks on the magnetic recording media in different positional relations to the tracks, the reproduction signals being arranged into that one unit for signal processing thereby generating the track-specific reproduction signals; and a phase alignment device configured to align phases of record signals between adjacent tracks among the plurality of tracks recorded by the recording device to the magnetic recording media.

A storage medium carries symbols representing digital information encoded in two dimensions. A method and apparatus recovers the symbols using oversampling in two dimensions and derives the information represented by the symbols. In one embodiment, the symbols are carried on motion picture film between the sprocket holes.

A method for automatically characterizing non-linearities of a perpendicular read-back signal of a recording system is disclosed. The method includes using dibit extraction to obtain a read-back signal having a main pulse and a plurality of echoes where the read-back signal exhibits a baseline shift. An area under the first echo is integrated to obtain a first area where the integrating subtracts any baseline shift area within the first echo and where the first echo is associated with a first non-linearity. The method integrates an area of the read-back signal under the main pulse to obtain a second area where the integrating subtracts any baseline shift area within the main pulse. A first parameter is computed that characterizes the first non-linearity based on the first area and the second area. The method may be applied to characterize several non-linearities.

Various embodiments of the present invention provide systems and methods for read sensor characterization. As an example, a data storage device is disclosed that includes a storage medium, a read / write head assembly disposed in relation to the storage medium, and a track width setting circuit. The track width setting circuit is operable to: write data to at least a first track and a second track on the storage medium, read data from the second track, determine an estimated track offset where interference from the data written to the first track is insubstantial, and modify at least the second track width based at least in part on the estimated track offset. The first track is a first track width and the second track is a second track width.

A method of protecting data on a recording medium against an adjacent track erase (ATE) effect, and a recording medium having a program therefor are provided. The method includes accumulating a number of turns of write operations in respective sub-areas, wherein the recording medium is divided into a plurality of sub-areas; and rewriting data on a sub-area of which an accumulated number of turns of write operations is greater than a limited number of turns of write operations. Accordingly, before data written on an adjacent track can be damaged by the ATE effect, data is rewritten and safely preserved.

A QCTC (Quasi-Complementary Turbo Code) generating apparatus having: a turbo encoder for generating an information symbol sequence and a plurality of parity symbol sequences by encoding the information symbol sequence; a channel interleaver for individually interleaving the symbol sequences, generating new parity symbol sequences by multiplexing the symbols of parity symbol sequences with the same priority levels, and serially concatenating the information symbol sequence and the new parity symbol sequences; and a QCTC generator for generating a sub-code with a given code rate by recursively selecting a predetermined number of symbols from the concatenated symbol sequence at a given starting position.

Clicks in voice and music signals are removed by detecting and interpolating the click. The use of a permanently set threshold value above the peak value of the audio signal is known for detecting the clicks, and interpolation carried out on the basis of the sample values before and after a click is known for filling them in. Disadvantages of these methods are, on the one hand, that many clicks do not have a larger amplitude than the peak signal and therefore remain undetected, and, on the other hand, interpolation is a highly complex procedure and is limited to a maximum click density. The invention provides for an error signal (en) to be determined by adaptive filtering (AF). A sample value is designated as distorted in the input signal (xn) if the absolute instantaneous value in the error signal (en) exceeds a dynamically adapted threshold value. The output signal of the adaptive filtering (yn) is used as a substitute value for the sample value designated as distorted, specifically both in the case of the signal which is output and in the input values of the adaptive filtering.

A charge / discharge control circuit for controlling current through an input / output audio device includes a first voltage reference; a second voltage reference and a waveform generation circuit responsive to the first and second voltage references for generating a multi-stage waveform profile which is approximately an inaudible waveform for suppressing audible artifacts in the input / output device.

Input buffer management of the playback control for MP3 players includes (1) initializing a totalizer to zero, (2) finding a synchronization word of a frame, (3) decoding a header, (4) calculating the size of a main_data field, and (5) decoding the enclosed audio data. If it is determined the value contained in the totalizer is less than the main_data_begin of this frame, store the main_data of the frame in an input buffer, add the size of the main_data to the totalizer, and repeat the process starting with finding the synchronization word of a next frame until the totalizer is greater or equal to the main_data_begin of the then current frame. At this point, all of the audio data required by the frame is currently available and decoding and playing can continue as normal.

A hard disk drive which can maintain a write property at a constant level by reflecting a temperature effect during a write parameter set process even when the hard disk drive is used under a condition different from one intended during manufacturing of the disk. The hard disk drive includes a disk, a thermister and a controller. The disk stores data and the thermister measures the temperature around the disk. The controller is coupled to the thermister and selects a parameter to be optimized from parameters related to a disk write operation. The controller writes arbitrary data to a test track on the disk to obtain a first bit error rate of the test track. The controller repeatedly writes arbitrary data to at least one track adjacent to the test track indicated by as many times as an adjacent track write count is based on an associated temperature measured by the thermister to obtain a second bit error rate of the test track. The controller sets a value of the selected parameter to determine a difference between the first bit error rate and the second bit error rate which is less than a predetermined criteria corresponding to an optimized value of the selected parameter in a disk zone to which the test track is located.

Various embodiments of the present invention provide systems and methods for reducing low frequency loss in a magnetic storage device. For example, a data processing circuit is disclosed that includes an amplifier, two filters and a summation element. The amplifier provides an amplified output that is filtered using a first of the two filters to create a first filtered output. The first filtered output is then filtered using the second of the two filters to create a second filtered output. The summation element sums the first filtered output with the second filtered output to provide a pole altered output.

A signal processing apparatus adapted for correcting non-linear distortion of a reproduction signal includes a secondary adaptive equalizing filter connected in parallel with a primary adaptive equalizing filter to correct non-linear distortion in an analog equalized signal. Filter outputs of the primary adaptive equalizing filter and the secondary adaptive equalizing filter are added at an adder, and the added output thus obtained is delivered to a phase interpolation filter as an equalized output. The phase interpolation filter performs interpolation of phase on the basis of a filter output of the primary adaptive equalizing filter and a filter output of the secondary adaptive equalizing filter. A filter output of the phase interpolation filter is delivered to an Information Technology research-phase-locked loop circuit.

An audio output apparatus having an audio codec for generating audio signals delivered to a speaker is provided with a device for preventing an audio pop noise caused by the bias voltage output from the audio codec, which includes a capacitor connected between an output end of the audio codec and the speaker, a capacitor charger for smoothly charging the capacitor to a predetermined voltage level, a switch arranged between the junction of the output end of the audio codec and the capacitor and the capacitor charger, and a control unit for controlling the codec, wherein the control unit turns on the switch and drives the capacitor charger before activating the audio codec, and then turns off the switch and terminates the operation of the capacitor charger if a predetermined charging time has elapsed. A method for preventing the audio pop noise caused by a bias voltage output from the audio codec includes smoothly charging the capacitor to have the same voltage level as the bias voltage of the audio codec before activating the audio codec, and activating the audio codec.

A reproduction signal evaluation method for evaluating quality of a reproduction signal reproduced from an information recording medium based on a binary signal generated from the reproduction signal using a PRML signal processing system, includes: a pattern extraction step of extracting, from the binary signal, a specific state transition pattern which has the possibility of causing a bit error; a step of computing a differential metric based on the binary signal; an extraction step of extracting the differential metric which is not greater than a predetermined signal processing threshold; a step of determining a mean value of the differential metrics which are not greater than the signal processing threshold and extracted in the extraction step; a standard deviation computing step of determining a standard deviation which corresponds to an error rate predicted from the mean value; and an evaluation step of evaluating a quality of the reproduction signal using the standard deviation.

In one illustrative example disclosed, a magnetic storage device includes at least one magnetic disk; a magnetic head which includes first and second read sensors; a suspension which supports the magnetic head relative to the magnetic disk; and read circuitry which includes a preamplifier. The preamplifier has a first input port coupled to the first read sensor; a second input port coupled to the second read sensor; a first bias source coupled to the first input port for actively current / voltage biasing the first read sensor; a second bias source coupled to the second input port for zero biasing the second read sensor; and a subtractor having first and second inputs coupled to the first and the second input ports, respectively. The first input of the subtractor is provided with a first signal which includes a read sensor data signal and an interference signal, whereas the second input of the subtractor is provided with a second signal which includes the interference signal but not the read sensor data signal. Thus, an output of the subtractor provides a read sensor signal without the interference signal.

A crosstalk removing device for use in a recorded information reproducing apparatus which is free from malfunctions even if a read sample value sequence, which has been read from a recording medium and sampled, is out of synchronization, and can immediately proceed to a crosstalk removing operation after the read sample value sequence recovers the synchronization. When crosstalk from adjacent tracks is removed from the read sample value sequence, which has been read from a recording medium and sampled, to produce a crosstalk removed read sample sequence, filter coefficients are derived for converging an error value present in the crosstalk removed read sample value sequence to zero, and the read sample value sequence is filtered on the basis of the filter coefficients to derive crosstalk components from the adjacent tracks. The crosstalk components are subtracted from the read sample value sequence to derive the crosstalk removed read sample value sequence. In this event, when the read sample value sequence remains in an asynchronous state, the read sample value sequence is filtered on the basis of predetermined fixed coefficient values instead of the filter coefficient to derive crosstalk components from the adjacent tracks.

The invention relates to a method for the recording and reading of data with a holographic write / read apparatus onto a holographic recording medium with a thin holographic recording layer. The medium is preferably an optical card (2). The recording of the information is in the form of data pages stored as thin Fourier holograms (61). According to the invention, it is foreseen to use reflected transmission and polarisation holography with different write and read wavelengths, and to correct during reading the distortion in the readout channel caused by the difference between the write and read wavelengths. The invention further relates to an apparatus and system for performing the method. There is also disclosed a method of coding the recorded information.

In an information recording medium, positions of pits are modulated in a direction intersecting a direction of reading of pits, so that a predetermined information is recorded. In this information recording medium, the whole of the predetermined information or a part of the predetermined information is randomized through the used of spread spectrum.

A QCTC (Quasi-Complementary Turbo Code) generating apparatus having: a turbo encoder for generating an information symbol sequence and a plurality of parity symbol sequences by encoding the information symbol sequence; a channel interleaver for individually interleaving the symbol sequences, generating new parity symbol sequences by multiplexing the symbols of parity symbol sequences with the same priority levels, and serially concatenating the information symbol sequence and the new parity symbol sequences; and a QCTC generator for generating a sub-code with a given code rate by recursively selecting a predetermined number of symbols from the concatenated symbol sequence at a given starting position.

A magnetic recording / reproducing apparatus is disclosed wherein reproduced signals read out from a plurality of recording tracks using a reproducing head can be separated into original recording signals of the recording tracks. Upon recording, an identification signal which has a recording wavelength equal to or greater than a minimum recording wavelength and causes no interference of any of the recording tracks with any adjacent one of the recording tracks is appended to and recorded together with a recording signal in order to allow, upon reproduction, acquisition of the position information of the reproducing head with respect to the plural recording tracks of the magnetic recording medium. Upon reproduction, a reproduced signal for each of the recording tracks of the magnetic recording medium is generated on the basis of the positional information read from the recording tracks.

Hardware-based methods and apparatus are provided for inter-track interference mitigation in magnetic recording systems using averaged values. Inter-track interference (ITI) is mitigated in a magnetic recording system by obtaining ITI cancellation data; and providing the ITI cancellation data for ITI mitigation, wherein the ITI mitigation is performed in combination with an averaging procedure for one or more of ITI mitigation of averaged data and averaging of ITI mitigated data. The sector is optionally decoded using the ITI mitigated samples. Samples for one or more side track sectors can also be averaged. The averaged side track samples can be provided as ITI cancellation data for ITI mitigation. The averaging procedure optionally applies a scaling factor to each read value.

A control circuit corrects duty-cycle distortion of clock signals accurately and with a fast and continuous response over a wide dynamic range. In one embodiment, the duty-cycle correction circuit includes a self-biased loop that corrects duty-cycle distortions to preferably less than + / −1%. The duty-cycle correction circuit also compensates for changes in a supply voltage. These corrections may take place on a continuous basis, not only during a testing period but also during normal operation of the host system driven by the clock signals.

A method and system are disclosed for compensating disturbance applied to a plant, such as a HDD component, controlled by a state control device having an estimator & controller. The estimator & controller is adapted to generate a first control signal in response to a state signal indicating an estimated state of the plant. A second control signal is generated by applying a transfer function H(s) having defined gain / frequency characteristics to a control signal derived from the first control signal. An overall control signal is generated in response to the second control signal and the control signal derived from the first control signal and applied to the plant.

A magnetic disk apparatus is configured such that a physical track number is converted into an absolute track number by making a track pitch in an absolute track area formed by a given magnetic head wider by a given amount than a track pitch in a corresponding absolute track area formed by a reference magnetic head if the number of absolute tracks is larger in the absolute track area formed by the given magnetic head than in, the absolute track area formed by the reference magnetic head although the number of physical tracks is identical in corresponding physical track areas between different magnetic disks. The given amount is commensurate with an unused area corresponding to a difference in the number of absolute tracks between the absolute track area formed by the given magnetic head and the absolute track area formed by the reference magnetic head.