Marvell International Limited

Marvellworld Trade Ltd.

Qiyue Zou

Gregory Burd

Michael Madden

Xueshi Yang

Supaket Katchmart

Mats Oberg

Vincent M Wong

Hongxin Song

Yifei Zhang

Kar Shing Chiu

Various embodiments provide the position error signal (PES) that is generated by the data read channel that uses internal signals such as analog-to-digital signals, recovered data bits and signals or other internal signals to determine read head off-track metrics. Several different metrics can be utilized including a normalized norm metric, a normalized cross correlation metric, and a cross correlation with detected data metric. These metrics can be utilized to determine off-track shift of one or more read heads such that the read head position can be corrected.

Digital data driven position error signal for magnetic recording

Systems and methods are provided for calibrating signals retrieved from a storage device using a first reader and a second reader. The systems and methods further include reading a first signal using the first reader and a second signal using the second reader. Control circuitry computes a calibration metric associated with the first reader and the second reader based on the combination of the first signal and the second signal. At least one of the first signal and the second signal is subsequently decoded based in part on the computed calibration metric.

Systems and methods for calibrating read and write operations in two dimensional magnetic recording

A read/write channel module for writing data to and reading data from a storage medium. A servo channel module is configured to recover a servo field from the storage medium in accordance with a read signal read from the storage medium and a first clock signal. A locator module is configured to determine, based on a location of the servo field recovered from the storage medium, a location of a predetermined bit pattern that is located subsequent to the servo field on the storage medium. A phase error calculator module is configured to estimate a phase error of a second clock signal based on the location of the predetermined bit pattern, wherein a phase and a frequency of the second clock signal are different than a phase and a frequency of the first clock signal, and adjust the phase of the second clock signal based on the estimated phase error.

Apparatus and method for adjusting a phase of a data clock signal using a predetermined bit pattern

Determining the radial position of a first read head of a storage device includes reading servo data from a storage media platter surface using the first read head, deriving from that servo data a first positron error signal representing a first estimate of the radial position of the first read head, reading the servo data from the storage media platter surface using a different read head, deriving from that servo data a second position error signal representing an estimate of the radial position of the different read head, and combining the first estimate of the radial position of the first read head and the estimate of the radial position of the different read head to obtain a revised estimate of the radial position of the first read head. The combining could include taking account of a known positional offset between the first read head and the different read head.

Method and apparatus for determining position of multiple drive heads

Systems, methods, and other embodiments associated with processing a read signal from a storage medium that includes continuous embedded position information are described. According to one embodiment, an apparatus includes read logic configured to control a storage device to generate the read signal by reading a first layer and a second layer of the storage medium. The first layer defines data and the second layer defines embedded position information. The apparatus includes data detection logic configured to process the read signal to recover the embedded position information. The read logic is configured to control the storage device based, at least in part, on the embedded position information.

Processing a data signal with an embedded position signal

Systems and methods for detecting cycle slip are provided. In some embodiments, a waveform that represents data samples is received. The waveform may include a predetermined preamble and a predetermined postamble. A first value representing a phase of the predetermined preamble of the waveform may be computed. A second value representing a phase of the predetermined postamble of the waveform may be computed. A detection is made as to whether cycle slip occurred during sampling the received waveform based on a comparison of the first value with the second value.

Systems and methods for detecting cycle slip and/or framing error

A system for providing an accumulated phase to an interpolator of a read channel, the interpolator configured to provide a digital clock signal. A frequency accumulator is configured to generate a frequency offset based on a difference between the digital clock signal and a desired clock signal. A zero phase start module is configured to, during a zero phase start, output an incremental phase jump. A phase accumulator is configured to generate the accumulated phase based on the difference between the digital clock signal and the desired clock signal, and, during the zero phase start, the incremental phase jump output by the zero phase start module, or the frequency offset generated by the frequency accumulator or a predetermined frequency offset.

Applying digital frequency offset to timing loop

Systems and techniques relating to control of magnetic recording devices are described. Such devices can contain a recording medium including magnetic data positions, servo sync marks (SSMs), and phase tracking fields (PTFs) arranged between first and second SSMs. A described technique includes producing, based on a read head's waveform from the recoding medium, a servo detect pulse indicating a SSM detection; producing, based on the waveform, a servo detect pulse that indicates a SSM detection; producing, responsive to the servo detect pulse, calibration pulses, each of the calibration pulses corresponding to a read head's passage over one of the PTFs; and controlling, responsive to the calibration pulses, adjustments of a phase of a write clock signal to align the write clock signal with at least a portion of the data positions, the adjustments being based on groups of samples of the waveform that respectively correspond to the PTFs.

Write clock phase tracking for magnetic recording device

The present disclosure includes systems and techniques relating to synchronization for writing to a recording medium. According to an aspect, an apparatus includes: circuitry configured to measure a timing difference based on a servo detect pulse and a write pulse, wherein the servo detect pulse comes from a detection of servo data from a recording medium including pre-defined data positions, and wherein the write pulse comes from a write clock signal used with the recording medium; and circuitry configured to control an adjustment to a phase of the write clock signal based on the timing difference to align the write clock signal with at least a portion of the pre-defined data positions.

Write clock rephase for magnetic recording device

Techniques are provided for performing bit-locked operations on media. A first control signal is received from a first source, and a second control signal is generated at a second source in response to receiving the first control signal. The media is accessed according to the second control signal. One or more synchronization markers are located during the accessing of the media, and bit-level synchronization between the second source and the media is achieved based, at least partially, on the one or more synchronization markers. A control operation is performed on the media with bit-level synchrony between the second source and the media.

Bit-locked interface for magnetic recording

Systems, methods, apparatus, and techniques are provided for controlling synchronization of a write clock. A frequency offset is estimated based, at least partially, on a location of the servo synchronization marker to produce the frequency offset estimate. A phase correction value and a frequency correction value associated with the write clock are obtained, and a data clock timing control signal is produced based on the frequency offset estimate, the phase correction value, and the frequency correction value. The data clock timing control signal is applied to a phase interpolator to modify a phase of the write clock.

Disk synchronous write architecture for bit-patterned recording

A system includes a detection module, an adjustment module, a phase shifter module, and a write module. The detection module: samples a sensor signal to generate a digital signal; based on the digital signal, detects a pattern of first bit islands on media; and based on the pattern, determines a phase error of the digital signal. The adjustment module generates a second clock signal based on the phase error and a first clock signal. The second clock signal is synchronized with start or end times of the first bit islands. The phase shifter module, based on a predetermined value, adjusts a phase of the second clock signal. The detection module samples the sensor signal based on the second clock signal with the adjusted phase. The write module, based on the second clock signal prior to being phase adjusted, writes data to the first bit islands or second bit islands.

Method and apparatuses for synchronizing writing of data with a pattern of bit islands of media

Systems and techniques relating to control of magnetic devices are disclosed. A described technique includes receiving a waveform via a head about a recording medium which includes data tracks and servo regions, detecting a servo region based on the waveform becoming an alternating signal, which is indicative of the head's path over discrete radially arranged magnetic strips in the servo region; performing a frequency synchronization of a read clock based on the detection to establish a frequency lock; performing a phase synchronization of the read clock to align a phase of the read clock with respect to acquired samples of the alternating signal; performing a synchronization of a write clock based on a write of a test sequence to the medium, the write clock being responsive to the frequency lock and the read clock; and writing, using the synchronized write clock, data to the medium for servo control.

Self servo write process for discrete track media

Synchronization technologies for disk drives are described. A described technique includes receiving a waveform produced by a read head operated with respect to a recording medium including magnetic data positions, a first servo sync mark (SSM), a second SSM, and phase tracking fields (PTFs); producing, based on the waveform, a servo detect pulse that indicates a detection of at least one of the SSMs; controlling a first adjustment of a phase of a write clock signal, the first adjustment being responsive to the servo detect pulse; producing, based on the write clock signal, samples of the waveform that correspond to the PTFs; and controlling second adjustments of the phase based on the samples to align the write clock signal with at least a portion of the data positions, the second adjustments being responsive to the PTFs, respectively.

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San Jose, CA, United States of America

Qiyue Zou