Abstract: A method of self servo-writing servo information to a plurality of disk surfaces in a disk drive that includes writing servo information to a plurality of disk surfaces in a first direction, writing servo information to a plurality of disk surfaces in a second direction, and determining an amount of overlap to be written on a reference surface with the reference head that will produce an overlap of servo information on each of the surfaces in the disk drive to which servo information is to be written. The method also includes switching to different tables when seeking across the overlap or border areas.

Abstract: Systems and methods of reading data from a storage device are provided. A first codeword and a second codeword are read from a storage device, where the second codeword is positioned after the first codeword. The first and second codewords are decoded in parallel, and the decoding of the second codeword completes before the decoding of the first codeword completes. The decoded second codeword and a signal indicating whether the decoding of the second codeword is complete are transmitted to control circuitry before the decoding of the first codeword completes.

Abstract: In one embodiment, a method for writing data to a magnetic tape utilizing a rate-(232/234) reverse concatenated modulation code includes receiving a data stream comprising one or more data sets, separating each data set into a plurality of sub data sets, encoding each sub data set with a C2 encoding, encoding each C2-encoded sub data set with the modulation code, encoding each modulated sub data set with a C1 encoding, and simultaneously writing the encoded modulated sub data sets to data tracks of the magnetic tape. Other methods for writing data to a magnetic tape utilizing a rate-(232/234) reverse concatenated modulation code are described according to various other embodiments.

Abstract: Decoding data written over a plurality of tracks includes selecting a mask that accounts for Inter-Symbol-Interference, the mask including channel coefficients and defining a trellis defining a plurality of states; receiving a signal corresponding to an input pixel from each of the plurality of tracks and generating equalized samples therefrom; computing transition branch probabilities for each input vector based on a Gaussian noise distribution using the equalized samples, ideal samples and a priori probabilities of the input vector; computing forward and backward probabilities via recursions using the computed transition branch probabilities; combining the forward, backward and transition branch probabilities to generate a-posteriori probabilities for the input vector; marginalizing the a-posteriori probabilities over values of neighboring pixels to generate an a-posteriori probability for a pixel of the input vector in a given state, and decoding the pixel as a first or second logical state from the margin

Abstract: A shingled magnetic recording (SMR) hard disk drive (HDD) essentially eliminates the effect of far track erasure (FTE) in the boundary regions of annular data bands caused by writing in the boundary regions of adjacent annular data bands. The extent of the FTE effect is determined for each track within a range of tracks of the track being written. Based on the relative FTE effect for all the tracks in the range, a count increment (CI) table or a cumulative count increment (CCI) table is maintained for all the tracks in the range. For every writing to a track in a boundary region, a count for each track in an adjacent boundary region, or a cumulative count for the adjacent boundary region, is increased. When the count reaches a predetermined threshold the data is read from that band and rewritten to the same band.

Abstract: A hard disk drive or other disk-based storage device comprises a storage disk, a read/write head configured to read data from and write data to the disk, and control circuitry coupled to or otherwise associated with the read/write head. The control circuitry comprises a write driver configured to generate a write signal for data to be written to the storage disk, and a multiple-slope transition controller associated with the write driver and configured to control a data transition in the write signal such that the data transition comprises at least two different segments each having a different slope, with the transition controller comprising separate slope control mechanisms for each of the segments. By way of example, the data transition may comprise a dual-slope transition having first and second segments arranged sequentially between a start point and an end point of the data transition.

Abstract: A method for selecting which tap coefficients of a programmable finite-impulse-response (FIR) equalizer to fix is disclosed. In one embodiment, such a method includes performing an initial calibration to determine an initial value for each tap coefficient of a FIR equalizer. These initial values may be used to produce a first waveform. The method then performs an operation on the first waveform to produce a second waveform comprising multiple lobes. The second waveform is then analyzed to determine one or more lobes of the second waveform that have the largest area. The method then fixes coefficients of one or more taps that are closest to the lobe or lobes having the largest area. A corresponding apparatus and computer program product are also disclosed.

Abstract: 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.

Abstract: A magnetic tape media for storing data includes at least one servo band extending along the magnetic tape media and having servo information encoded by an M-ary alphabet A comprising M>2 different symbols and is arranged in a set of words. Each word of the set of words contains synchronization information, wherein each symbol used for representing the synchronization information is from a set B of m symbols, which set B is a proper subset of the symbols in the alphabet A such that 1?m?M; longitudinal position information, wherein each symbol used for representing the longitudinal position information is from a set C of M-m symbols, which set C is a complementary set to set B; and other information, wherein each symbol used for representing the other information is from the set C of M-m symbols.

Abstract: A method and apparatus for reducing noise in a communication signal is provided. The method includes converting raw channel data from the communication signal to a sequence of transition code symbols, each symbol having a plurality of bits, each bit having a position within the symbol. The method also includes sending the bits of each symbol to a plurality of bins, each bin corresponding to the position of each bit within the symbol. For each bin having a number of transitions greater than a number of non-transitions, the method also includes flipping every bit in the bin and setting a corresponding bit in a flip control word to a first value. The method still further includes binary adding the flip control word to each transition code symbol.

Abstract: A detector recovers servo data from a servo signal generated by a read-write head, and determines the head-connection polarity from the recovered servo data. Such a detector allows a servo circuit to compensate for a reversed-connected read-write head, and thus allows a manufacturer to forego time-consuming and costly testing to determine whether the head is correctly connected to the servo circuit.

Abstract: An initial phase offset between a center track and a side track is determined. An initial side track pulse shape is determined using the initial phase offset and side track interference. The initial side track pulse shape minimizes a contribution of the side track interference to a center track bit. The contribution of the side track interference is removed from the center track bit using the initial side track pulse shape and the side track interference.

Abstract: In a perpendicular magnetic recording system, the data that is being written by the write channel is fed back into the read channel. The read channel processes the data and decides if the written sequence is likely to have very poor DC characteristics. If that is the case, the write channel changes a scrambler seed and rewrites the data using the new scrambler seed. The data may also be inspected for patterns that might cause large baseline wander before being written to disk, i.e., in the write channel. A data sequence may be repeatedly scrambled and encoded until an acceptable level of estimated DC-wander has been achieved. The data sequence may then be written to disk.

Abstract: A processing unit performs a method including controlling a reading-out of data from a first storage medium at a predetermined read-out data rate to produce inputted data, and controlling a compression of the inputted data to produce first compressed data of a first compressed format. The method includes controlling a storage of the first compressed data in a second storage medium at a faster writing data rate than the predetermined read-out data rate, controlling a reading-out of second compressed data of a second compressed format from the second storage medium, and controlling a decompression of the second compressed data to produce decompressed data. The method also includes controlling simultaneously the storage of the first compressed data in the second storage medium, the reading-out of the second compressed data from the second storage medium, and audibly reproducing the decompressed data. The first compressed format is different from the second compressed format.

Abstract: During a read-after-write operation on magnetic tape, a first SCO is formed which includes two encoded processed user data units and is one of T SCOs in a first SCO set. The user data units are each one of T user data units in first and second user data unit sets, respectively, within the first SCO set. The first SCO set is written to the magnetic tape and is immediately read. When an error is detected in one of the user data units, a second SCO is formed to include the first user data unit and, only if an error is not detected in a user data unit in the other user data unit set, to not include the other user data unit, the second SCO being one of T SCOs in a second SCO set. Then, the second SCO set is rewritten to a later position on the tape later.

Abstract: Systems and methods for retrieving data stored on a peripheral storage device such as a magnetic tape drive or disk drive include string searching using the peripheral storage device resources without transferring data to the requesting host computer and transferring only data blocks with matching data to the associated host computer to conserve host resources and data channel and/or network bandwidth.

Abstract: According to one embodiment, a disk storage device includes: a disk on which a servo pattern is recorded; a head; a driver; a signal generator; a demodulator; and a controller. Position signals for detecting an offset position from a center of a track are recorded in a recording area of a servo pattern. The signal generator generates a first timing signal indicating a timing for reading the position signals. When the controller performs a seek operation for moving the head to a target track, the signal generator generates a second timing signal. The period of the second timing signal for reading each of the position signals is made shorter than that of the first timing signal. A center time of the period of the second timing signal is shifted closer to a demodulation center time corresponding to a center of the recording area than that of the first timing signal.

Abstract: A video recording system is provided in which reliability of information supplied from a video camera to control recording and the like is improved when video being obtained by a video camera is recorded in one or more VTRs. In the video recording system, the video camera multiplexes: control information to control the VTR in accordance with an operational status of an operation unit of the video camera and a video signal from an imaging unit of the video camera, and transmits the result to the VTR as a transmission serial digital signal. The VTR separates the video signal and the control information from the serial digital signal and controls a video recording system of the VTR based on the control information.

Abstract: A method and apparatus for reducing noise in a communication signal is provided. The method includes converting raw channel data from the communication signal to a sequence of transition code symbols, each symbol having a plurality of bits, each bit having a position within the symbol. The method also includes sending the bits of each symbol to a plurality of bins, each bin corresponding to the position of each bit within the symbol. For each bin having a number of transitions greater than a number of non-transitions, the method also includes flipping every bit in the bin and setting a corresponding bit in a flip control word to a first value. The method still further includes binary adding the flip control word to each transition code symbol.

Abstract: Data storage systems are provided. Data storage systems illustratively include a recording head having a writing element and a bit patterned medium having a plurality of media dots. In some embodiments, the plurality of media dots pass the recording head at a media dot frequency. In some embodiments, the writing element writes data to the bit patterned media at a writing frequency that is less than the media dot frequency.

Abstract: In a perpendicular magnetic recording system, the data that is being written by the write channel is fed back into the read channel. The read channel processes the data and decides if the written sequence is likely to have very poor DC characteristics. If that is the case, the write channel changes a scrambler seed and rewrites the data using the new scrambler seed. The data may also be inspected for patterns that might cause large baseline wander before being written to disk, i.e., in the write channel. A data sequence may be repeatedly scrambled and encoded until an acceptable level of estimated DC-wander has been achieved. The data sequence may then be written to disk.

Abstract: According to one embodiment, a non-linearity measurement apparatus includes a first measurement module, a second measurement module, and a calculation module. The first measurement module is configured to measure a component of a first higher harmonic from a reproduced signal of a first signal recorded on a magnetic recording medium. The second measurement module is configured to measure a component of a second higher harmonic from a reproduced signal of a second signal recorded on the magnetic recording medium. The calculation module is configured to calculate a non-linear transition shift of the magnetic recording medium by calculating an arcsine function of a value obtained by dividing the component of the second higher harmonic by the component of the first higher harmonic.

Abstract: A method and apparatus for reducing noise in a communication signal is provided. The method includes converting raw channel data from the communication signal to a sequence of transition code symbols, each symbol having a plurality of bits, each bit having a position within the symbol. The method also includes sending the bits of each symbol to a plurality of bins, each bin corresponding to the position of each bit within the symbol. For each bin having a number of transitions greater than a number of non-transitions, the method also includes flipping every bit in the bin and setting a corresponding bit in a flip control word to a first value. The method still further includes binary adding the flip control word to each transition code symbol.

Abstract: A sequential data storage medium, such as for example and without limitation a magnetic tape, comprising a sequence of plurality of servo patterns encoded therein, which provide lateral position information and LPOS information. Each servo pattern comprises a first burst comprising a first pulse, a second pulse, a third pulse, a fourth pulse and a fifth pulse and a second burst comprising a sixth pulse, a seventh pulse, an eighth pulse, a ninth pulse and a tenth pulse. The widths of the plurality of pulses, in combination with the spacings between the plurality of pulses, encode two bits of data.

Abstract: An object of the present invention is to embed information while making effective use of a recording area at the time of recording data. To this end, a controller in a tape drive includes: a storage unit which stores information desired to be embedded; an acquisition unit which acquires the information stored in the storage unit; a writing unit which repeatedly writes a CQ set determined on the basis of the acquired information the number of times determined on the basis of this information; a reading unit which reads data in which information is embedded; and an identification unit which identifies information embedded in the read data, and which determines whether or not the read data can be used and the like, in comparison with this information and the information stored in the storage unit.

Abstract: Methods, logic, apparatus and computer program product write data, comprising less than a full Data Set, to magnetic tape. Data is received from a host, a do-not-interleave command is issued and C1 and C2 ECC are computed. Codeword Quad (CQ) sets are then formed. At least one CQ set of the Data Set is written to a magnetic tape in a non-interleaved manner and a Data Set Information Table (DSIT) is written to the magnetic tape immediately following the at least one written CQ set. An address transformation may be used to cancel interleaving. Writing a CQ set may include writing a plurality of contiguous instances of the CQ set to the magnetic tape to maintain the effectiveness of ECC capability.

Abstract: A method and system for reading readback waveforms representing written magnetization states of a pair of magnetic islands of a two-level patterned magnetic recording medium, and a structure that include a multi-level patterned magnetic medium. Reading the readback waveform representing the written magnetization state includes: identifying the written magnetization state by decoding the readback waveform; and displaying and/or recording the written magnetization state. The magnetic medium of the structure includes distributed pillars. Each pillar includes a first and second magnetic island. Each magnetic island has a magnetic easy axis oriented at a first tilt angle (?1) and a second tilt angle (?2), wherein ?1 and ?2 satisfy: ?1??2, either or both of ?1 and ?2 differing from 0, 90, 180, and 270 degrees, or combinations thereof.

Abstract: A synchronous read channel having a single chip integrated circuit digital portion which provides digital gain control, timing recovery, equalization, digital peak detection, sequence detection, RLL(1,7) encoding and decoding, error-tolerant synchronization and channel quality measurement is disclosed. The integrated circuit accommodates both center sampling and side sampling, and has a high degree of programmability of various pulse shaping and recovery parameters and the ability to provide decoded data using sequence detection or digital peak detection. These characteristics, together with the error-tolerant sync mark detection and the ability to recover data when the sync mark is obliterated, allow a wide variety of retry and recovery strategies to maximize the possibility of data recovery.

Abstract: A method for dividing a data area on a disk into a plurality of concentric zones and determining a format for each zone so that data tracks in the zone have the same number of data sectors. The method includes dividing a data area into a plurality of zones with provisional boundaries. The method also includes determining a linear recording density for a selected zone. The method further includes selecting the number of data sectors per data track corresponding to the determined linear recording density from specified values. Moreover, the method includes resetting a boundary of the zone at a new boundary shifted from the provisional boundary according to a selected value.

Abstract: A synchronous read channel having a single chip integrated circuit digital portion which provides digital gain control, timing recovery, equalization, digital peak detection, sequence detection, RLL(1,7) encoding and decoding, error-tolerant synchronization and channel quality measurement is disclosed. The integrated circuit accommodates both center sampling and side sampling, and has a high degree of programmability of various pulse shaping and recovery parameters and the ability to provide decoded data using sequence detection or digital peak detection. These characteristics, together with the error-tolerant sync mark detection and the ability to recover data when the sync mark is obliterated, allow a wide variety of retry and recovery strategies to maximize the possibility of data recovery.

Abstract: For writing data to multi-track tape, a received data set is received and segmented into unencoded subdata sets, each comprising an array having K2 rows and K1 columns. For each unencoded subdata set, N1-K1 C1-parity bytes are generated for each row and N2-K2 C2-parity bytes are generated for each column. The C1 and C2 parity bytes are appended to the ends of the row and column, respectively, to form encoded C1 and C2 codewords, respectively. All of the C1 codewords per data set are endowed with a specific codeword header to form a plurality of partial codeword objects (PCOs). Each PCO is mapped onto a logical data track according to information within the header. On each logical data track, adjacent PCOs are merged to form COs which are modulation encoded and mapped into synchronized COs. Then T synchronized COs are written simultaneously to the data tape where T is the number of concurrent active tracks on the data tape.

Abstract: To effectively suppress a signal in a low frequency region in which the medium noise and the signal distortion are concentrated, and in order to effectively utilize a detected component of the reproduced signal in the low frequency region, a target of partial response equalization to the perpendicularly recorded/reproduced signal is set so that the low-frequency component around the direct current is suppressed to a regulated quantity for both the effective suppression and the effective utilization. Accordingly, a maximum-likelihood decoding process is carried out through the target of partial response equalization. Reliability of data detection is made higher and a signal-to-noise ratio is improved, so that the noise from the recording medium can be reduced more and it is possible to provide a high-density magnetic recording/reproducing apparatus.

Abstract: A magnetic disk controller includes a first buffer that includes a first storage area that stores former portions of pieces of writing data, and a second storage area that stores latter portions of pieces of writing data; an encoding unit that encodes a former portion of the first piece of writing data; a second buffer that stores the encoded former portion of the first piece of writing data; and a buffer control unit that writes the encoded former portion of the first piece of writing data into a first sector of the magnetic disk. The encoding unit encodes the latter portion of the first piece of writing data. The second buffer stores the encoded latter portion of the first piece of writing data. The buffer control unit, writes the encoded latter portion of the first piece of writing data into the first sector of the magnetic disk.

Abstract: A magnetic recording and reproduction method includes the steps of recording a plurality of tracks which make a unit for a signal process for data detection by means of a recording head on a magnetic recording medium, and reproducing signals of the plural tracks by a plural number of times in different positional relationships to the tracks by means of a reproduction head which can reproduce a signal across the plural tracks of the magnetic recording medium, collecting the reproduction signals in the unit and performing a signal process for the unit to produce reproduction signals for the individual tracks.

Abstract: A magnetic disk controller includes a first buffer that includes a first storage area that stores former portions of pieces of writing data, and a second storage area that stores latter portions of pieces of writing data; an encoding unit that encodes a former portion of the first piece of writing data; a second buffer that stores the encoded former portion of the first piece of writing data; and a buffer control unit that writes the encoded former portion of the first piece of writing data into a first sector of the magnetic disk. The encoding unit encodes the latter portion of the first piece of writing data. The second buffer stores the encoded latter portion of the first piece of writing data. The buffer control unit, writes the encoded latter portion of the first piece of writing data into the first sector of the magnetic disk.

Abstract: An apparatus includes a disk arrangement, a first signal processing path configured to output data from the disk arrangement according to a first protocol, a second signal processing path configured to output data from the disk arrangement according to a second protocol, and an interface including a set of electrical conductors and a mode control unit. The mode control unit is configured to output data from the first signal processing path on the set of electrical conductors according to the first protocol and to output data from the second signal processing path on the set of electrical conductors according to the second protocol according to a control signal received by the mode control unit. The second protocol is different from the first protocol.

Abstract: Systems and techniques relating to interpreting signals on a noisy channel with polarity uncertainty. A signal processor, such as a read channel transceiver device usable in a magnetic recording system, includes a detector operable to find a data pattern that indicates control information in a read signal and to determine a signal polarity of the read signal by determining Euclidean distances between a sampled sequence from the read signal and multiple possible sequences corresponding to preamble-shifted and polarity-reversed versions of the data pattern. The read signal is obtained from a partial response channel, such as in a storage device, and the data pattern can be a servo mark selected based on Euclidean distances between the servo mark and preamble-shifted and polarity-reversed versions of the servo mark generated according to a target channel and an encoding scheme specified for the storage medium.

Abstract: Methods, logic, apparatus and computer program product write data, comprising less than a full Data Set, to magnetic tape. Data is received from a host, a do-not-interleave command is issued and C1 and C2 ECC are computed. Codeword Quad (CQ) sets are then formed. At least one CQ set of the Data Set is written to a magnetic tape in a non-interleaved manner and a Data Set Information Table (DSIT) is written to the magnetic tape immediately following the at least one written CQ set. An address transformation may be used to cancel interleaving. Writing a CQ set may include writing a plurality of contiguous instances of the CQ set to the magnetic tape to maintain the effectiveness of ECC capability.

Abstract: For writing data to multi-track tape, a received data set is received and segmented into unencoded subdata sets, each comprising an array having K2 rows and K1 columns. For each unencoded subdata set, N1?K1 C1-parity bytes are generated for each row and N2?K2 C2-parity bytes are generated for each column. The C1 and C2 parity bytes are appended to the ends of the row and column, respectively, to form encoded C1 and C2 codewords, respectively. All of the C1 codewords per data set are endowed with a specific codeword header to form a plurality of partial codeword objects (PCOs). Each PCO is mapped onto a logical data track according to information within the header. On each logical data track, adjacent PCOs are merged to form COs which are modulation encoded and mapped into synchronized COs. Then T synchronized COs are written simultaneously to the data tape where T is the number of concurrent active tracks on the data tape.

Abstract: Servo patterns for patterned media. The servo pattern includes specification of cylinder/track ID with and without a Gray code. The servo pattern space is minimized by the optimum usage of the islands. This is achieved by island allocation rules to take advantage of non-magnetic island. The island allocation also provides for easier lift-off. Logic is used to encode and decode the Gray code. Further, the Gray code is designed to stabilize the magnetic island/non-magnetic island ratio to allow for easier manufacture.

Abstract: A signal detector is provided to detect symbols in a read back signal. The signal detector includes a first detector to generate raw decisions as a function of the read back signal and to generate at least one next best decision. A list-aided decoder generates the final decision based on both the raw decisions and the at least one next best decision from the first decoder.

Abstract: Provided are a bit patterned medium having a super track, a reading head which reads data recorded on the bit-patterned medium, and a hard disk drive (HDD) for recording/reading data on/from the bit patterned medium. The bit patterned medium includes a substrate, and a recording layer formed with a plurality of bit cells separated from each other along a plurality of tracks forming concentric circles having different radii on the substrate, wherein each track includes a super track including a plurality of sub-tracks, and bit cells formed on one of the sub-tracks are arranged at different positions in a circumference direction of the recording layer to bit cells formed on adjacent sub-tracks. The reading head which reads data recorded on a bit patterned medium has a width in a cross-track direction sufficient for reading data of an equal number of bit cells as the plurality of sub-tracks.

Abstract: An apparatus and associated method are described for use in a disk drive including a disk that that is supported for controlled rotation and for cooperating with a transducer arrangement for accessing the disk in performing a data operation. The disk includes an arrangement of servo track wedge segments for storing servo data such that a set of servo data is periodically available as the disk is rotated in relation to the transducer arrangement and the servo track wedges are separated by an arrangement of user data wedge segments for use in storing user data. Generally, a controller IC and a channel IC are provided. The servo data is transferred from the channel IC to the controller IC using one data protocol and user data is bidirectionally transferred between the channel IC and the controller IC using a different data protocol.

Abstract: A magnetic recording disk drive has a disk with pre-patterned nondata servo sectors extending generally radially across the data tracks. The disk may be a patterned-media disk with both pre-patterned data islands and pre-patterned nondata servo sectors. The servo sectors include a synchronization pattern of generally radially directed discrete magnetized marks, and first and second position error signal (PES) fields of generally radially directed discrete magnetized stripes. Each stripe in each of the two fields comprises a plurality of radially spaced discrete servo islands, each island having a radial height of approximately Tp, where Tp is the radial spacing of the track centerlines. In each field, the servo islands in alternating stripes in the along-the-track direction are shifted radially by approximately Tp. In the first PES field, the islands are centered at the midline between two adjacent track centerlines, and in the second PES field the islands are centered at a track centerline.

Abstract: Methods, circuits, and systems for processing a preamble field in a read channel (e.g., in a magnetic storage device such as a hard disk drive). The methods generally include the steps of (a) reading the preamble field, wherein the preamble field comprises a repetitive bit pattern having a logical transition every x bit periods, where x is an integer of at least 3 when d is 0 or 1, or where x is an integer of at least d+2 when d is greater than 1, and (b) processing the repetitive bit pattern. The methods may further relate to processing the preamble for synchronization with the read channel and/or for measuring the fly height of a read/write head. The invention also relates to methods of enabling read channel synchronization and/or fly height measurement.

Abstract: Servo patterns for patterned media. The servo pattern includes specification of cylinder/track ID with and without a Gray code. The servo pattern space is minimized by the optimum usage of the islands. This is achieved by island allocation rules to take advantage of non-magnetic island. The island allocation also provides for easier lift-off. Logic is used to encode and decode the Gray code. Further, the Gray code is designed to stabilize the magnetic island/non-magnetic island ratio to allow for easier manufacture.

Abstract: A phase locking apparatus is disclosed which, includes a phase error information detecting device to detect phase error information indicating the phase error. The device has a phase position determining device to determine, based on run length limited information, whether or not phase positions of a first and second value from among sampling values constituting synchronous data are under a reverse phase condition in effect when only one of the first and the second values is in excess of a predetermined threshold, and a phase error information calculating device to calculate the phase error information in each of two cases determined, one with the reverse phase condition found to be in effect and the other without effect.

Abstract: A coding/decoding part performs codes and decodes a given signal in one of a plurality of coding/decoding modes of different bit rates; and a control part sets a predetermined bit rate to be applied by the coding/decoding part in case a given signal is output after being coded and decoded by said coding/decoding part without storage thereof in a predetermined recording medium.

Abstract: Method and apparatus for magnetic tape recording where the magnetic tape has data and servo tracks, and address or other positioning information is encoded on the servo track. A servo track burst pattern is provided whereby certain of the bursts define a gap between the stripes of the first and second half of the burst, each burst including a certain number of the stripes. The presence of the gap in a burst indicates a first binary state, which may be defined as a digital one, and the absence of the gap defines the second binary state, which may be defined as digital value 0. Hence by defining a set of 1s and 0s, longitudinal positioning or address information is encoded on the servo track, thereby improving servo track following of a tape drive.

Abstract: A method is disclosed for determining position information of a transducer. At least a first code and a second code are chosen. The first code has different characteristics than the second code. User data written to a first sub-track is encoded with the first code and user data written to a second sub-track is encoded with the second code. The first code read from the first sub-track is obtained and the second code read from the second sub-track is obtained. Position information of the transducer is extracted from the obtained characteristics of the first code and the obtained characteristics of the second code.