Samsung Electronics Co., Ltd.

Seagate Technology Incorporated

Yawshing Tang

Carl Xiaodong Che

Na-Young Kim

Na Young Kim

Mike Suk

SungChang Lee

Xiaodong Che

Peng Luo

Haejung Lee

This application discloses a message format including a data payload of N bits and a corrector component encoding a checksum to correct the checksum of single bit slipping noise, where the checksum is the sum of each data payload bit by its position modulo N+1. The corrector component may encode a second checksum derived from the checksum that may also be included in the message and so on. Apparatus embodiments may include a transmitter generating a transmitted message of this format and/or a receiver using a received message that may be corrupted from the transmitted message through bit slipping in the form of bit insertion or bit deletion.

Apparatus for correcting single bit insertion or deletion in a data payload with a checksum corrector

A hard disk drive with a disk that has a plurality of data bits. The drive includes a circuit that reads each data bit n times and selects a value for the bit based on a reliability factor. The circuit may select a bit based at least in part on the most frequent occurrence of one of a plurality of values. For example, if more 0s occurred than 1s the bit would be set to 0. The reliability factor may be a ratio of the occurrence of 0s to the occurrence of 1s. A bit can be not selected or deselected if the reliability factor exceeds a threshold value.

Hard disk drive with data error recovery using multiple reads and derived reliability information

A hard disk drive that includes a head that is coupled to a disk. The disk drive further includes a comparator circuit that is coupled to the head. The comparator circuit receives a synchronization signal and a write clock. The comparator generates a write error signal if a comparison of the synchronization and write clock signals exceeds a threshold. The write error signal can inhibit a write operation or cause a rewrite of data.

Synchronous writing with timing error detection in bit patterned media disk drives

This application discloses a hard disk drive and operates it based upon using a first and third harmonic amplitude generated from reading a repeated pattern of bits written to a track on a disk surface. Both amplitudes are used to create a first data set and the third harmonic amplitude is used as a single tone to create a second data set. A conversion factor between these two is determine, which may be used to convert the first data set under other conditions into a temperature insensitive table of the electrical stimulus of a vertical micro-actuator and the flying height change of the slider. The hard disk drive may be calibrated during manufacture and/or in the field.

Method and apparatus for estimating flying height in a hard disk drive

A hard disk drive with a disk that has a plurality of data bits. The drive includes a circuit that reads each data bit n times and selects a value for the bit based on the most frequent occurrence of one of a plurality of values. This process provides a voting technique that enhances the quality of accurately captured data.

Data error recovery using voting on multiple retrials

A hard disk drive with a patterned disk that has a plurality of data fields. Each data field includes a sync field and a plurality of sync marks. Data is written onto the patterned disk in accordance with a write clock. The write clock is generated and synchronized by the sync field and the sync marks. The sync marks are dispersed throughout the data field so that the write clock is resynchronized as data is written onto the field.

Write timing system for hard disk drives with bit patterned media

A hard disk drive with a disk that has a plurality of data fields. Each data field includes a sync field and a plurality of sync marks. Data is written onto the disk in accordance with a write clock. The write clock is generated and synchronized by the sync field and the sync marks. The sync marks are dispersed throughout the data field so that the write clock is resynchronized as data is written onto the field.

Increased format efficiency using disk synchronized write

A hard disk drive with a disk that includes a first group of tracks and a second group of tracks. The second group of tracks are used to write large blocks of data. For example, data in the second group may be video or audio. The second group of tracks has a higher track density than the first group of tracks. The large data block is written sequentially in the second group of tracks so that there is only one adjacent track write within the group. Using only one adjacent track write allows the tracks within the second group to be overlapped to increase track density.

Large data block written on overlapping tracks in a hard disk drive

A hard disk drive that includes a disk and a head that is separated from the disk by a flying height. The disk drive also includes a circuit that determines the flying height from an equation that uses a third harmonic of a read signal. The read signal includes a data pattern that is a product of a first data pattern and a second data pattern. The resultant data pattern provides a third harmonic with a relatively high magnitude and improved signal to noise ratio.

Data pattern for fly height measurement

A hard disk drive that determines a flying height from a ratio of a first harmonic transfer function and a third harmonic transfer function. The transfer functions can be determined from a response to an impulse function. The impulse function (also known as an impulse response) can be a playback waveform de-convolved by channel data sequence. Any change in the ratio of the first and third harmonic transfer functions corresponds to a change in the flying height. The disk drive may utilize the transfer function ratios in a feedback routine to control the flying height.

Harmonic measurement for head-disk spacing control using user data

A disk drive that includes a head and a disk. The disk drive also includes a circuit that can detect head/disk contact from a jitter determined from a read signal provided by the head. The jitter may correspond to the time interval between two detected sync marks. Alternatively, the jitter may correspond to a change in frequency of a read clock generated from the read signal. These approaches allow for detection of head movement in a down track direction. Down track is a direction that is essentially parallel with the longitudinal axis of the head.

Detecting head/disk contact using timing jitter

A hard disk drive that includes a disk that contains at least one signal and a head that is coupled to the disk. The disk drive also contains a circuit that includes a data sampler that generates a plurality of data samples from the signal, a harmonic sensor coupled to the data sampler and a spectral power accumulator coupled to the harmonic sensor. The harmonic sensor accumulates the data samples. The circuit includes a window generator that determines a window length of the data samples accumulated by the harmonic sensor. The spectral power accumulator accumulates the windows of sample data accumulated by the harmonic sensor. The sample data accumulated by the spectral power accumulator can be accessed by a processor that performs a spectral analysis of the data.

Timing insensitive method and apparatus for spectral analysis in a disk recording system

A hard disk drive with a disk that contains a target track and an adjacent track. The drive includes a circuit that determines an error in data read from the target track. Data from the adjacent track is stored in memory. The adjacent track is then erased and the target track data is re-read from the target track. Erasing the adjacent track allows the target track data to be read without adjacent track interference. The data from the adjacent track is typically rewritten onto the disk from memory so no data is lost.

Data recovery through eliminating adjacent track interference

A hard disk drive with an encoder that writes data onto a disk in accordance with a plurality of first codes. Each code contains a plurality of digital bits. The first codes are selected so that if a bit is added or dropped during a write or read process the resulting bitstream can only be one of the selected first codes. This allows the bitstream to be accurately decoded to detect and correct for the added/dropped bit.

Method for correcting added and lost bits in a hard disk drive using error correction codes

A hard disk drive that determines a flying height from a slope of a line created from a ratio of amplitudes of frequencies in response to impulse functions. A first set of amplitudes of reference frequencies can be determined from a reference impulse. A second set of amplitudes of data frequencies can be determined from a data impulse during operation of the disk drive. Ratios of amplitudes of the data and reference frequencies at different discrete frequencies can be plotted. The slope of the plotted line corresponds to the difference between the flying height when the reference impulse is generated and the flying height when the data impulse is generated. The disk drive may utilize the slope in a feedback routine to control the flying height.

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Saratoga, CA, United States of America

Yawshing Tang