Marvell International Limited

Marvell Asia Pte., Ltd.

Hongxin Song

Zining Wu

Michael Madden

Gregory Burd

Nitin Nangare

Shaohua Yang

Xueshi Yang

Panu Chaichanavong

Hongwei Song

Seo-How Low

Qiyue Zou

Mats Oberg

Chi Fung Cheng

Jun Gao

Arshan Aga

Ke Du

A method of recovering a servo write frequency, to read servo wedge data from a rotating magnetic storage medium having at least one servo wedge that includes a servo preamble written at a known preamble frequency, includes analyzing samples of data read from the rotating magnetic storage medium to identify samples in which energy at the known preamble frequency exceeds a predetermined threshold, declaring the location of the servo preamble based on the identification of the samples in which energy at the known preamble frequency exceeds the predetermined threshold, deriving a phase angle from the samples in which the energy at the known preamble frequency exceeds the predetermined threshold, updating an accumulated phase angle using the derived phase angle, and using the updated accumulated phase angle to start a timing recovery loop to recover the servo write frequency. The analyzing and deriving may be performed using a spectral analysis operation.

Digital timing recovery for servo operations during start-up mode

A receiver device receives a signal via a communication channel, the signal (i) having been transmitted by a transmitter device, and (ii) corresponding to a pseudorandom bit sequence (PRBS). The receiver device correlates the received signal with a known signal to generate a correlation signal. The known signal includes the PRBS. The receiver device identifies one or more characteristics of the correlation signal, and determines one or more parameters of the communication channel using the identified one or more characteristics of the correlation signal. The receiver device i) uses the one or more parameters corresponding to the communication channel to process subsequent signals received via the communication channel, and/or ii) communicates the one or more parameters to the transmitter device to prompt the transmitter device to preprocess subsequent signals to be transmitted via the communication channel by the transmitter device.

Using dipulse response to detect channel parameters

Systems, methods, apparatus, and techniques are provided for producing an estimate of a digital sequence. A continuous-time signal is obtained. The continuous-time signal is sampled with an oversampling factor to produce a discrete-time signal corresponding to the continuous-time signal. A phase offset estimate of the continuous-time signal is produced based on the discrete-time signal. The discrete-time signal is interpolated based on the phase offset estimate to produce an interpolated discrete-time signal. The interpolated discrete-time signal is processed to produce an estimate of a digital sequence.

Repeated runout (RRO) zero phase start (ZPS)

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

A non-linear detector for detecting signals with signal-dependent noise is disclosed. The detector may choose a data sequence that maximizes the conditional probability of detecting the channel data. Since the channel may be time-varying and the precise channel characteristics may be unknown, the detector may adapt one or more branch metric parameters before sending the parameters to a loading block. In the loading block, the branch metric parameters may be normalized and part of the branch metric may be pre-computed to reduce the complexity of the detector. The loading block may then provide the branch metric parameters and any pre-computation to the detector. The detector may then calculate the branch metric associated with the input signal and output the channel data.

Nonlinear detectors for channels with signal-dependent noise

Systems and methods for the correction of DC noise in signals read by a head of a disk drive are presented. Circuitry on a first data path may be configured to filter an input signal to remove a DC component. Acquisition parameters on the first data path may be configured based on the filtered signal. Circuitry on a second data path may be configured to adjust the input signal based on the configured acquisition parameters. A mean of a window of data samples of the adjusted input signal may be computed. Based on the computed mean, a correction may be applied to the adjusted input signal until a stopping rule is satisfied.

ACQ in the presence of baseline pop

A system including an analog front end module, an equalizer module, a detector module, and a gain module. The analog front end module is configured to sample a signal read from a storage medium, convert the sampled signal into a digital signal, and output the digital signal. The equalizer module is configured to equalize the digital signal and output a data vector that corresponds to the equalized digital signal. The data vector represents data in the signal read from the storage medium. The detector module is configured to output a decision vector that corresponds to a noise-free ideal output vector of the decoded data vector. The gain module is configured to calculate a gain value based on the decision vector and the data vector, apply the gain value to the data vector, and output a revised data vector based on the data vector and the applied gain value.

Systems and methods for revising data in a signal read from a storage medium according to a calculated gain

A system including an analog front end module to receive a first signal generated by reading data from a storage medium storing the data in concentric tracks, sample the first signal, and output a second signal based on the sampling of the first signal. An equalizer module generates a first vector based on the second signal. The first vector represents the data in the first signal. A detector module generates a second vector based on the first vector. The second vector represents a noise-free vector corresponding to the first vector. A re-timing module re-samples a plurality of samples in the first vector based on the second vector and generates a third vector based on the re-sampling of the plurality of samples in the first vector. An inter-track interference cancellation module removes inter-track interference from the third vector.

Systems and methods for inter-track interference cancellation in magnetic recording channels

A receiver for a hard disk drive system includes an analog front end module configured to receive a read-back signal and to output a digital read-back signal. An equalizer module is configured to generate a data vector based on the digital read-back signal. A detector module is configured to generate a decision vector based on the data vector. A gain module is configured to generate a scalar gain vector and to generate a revised data vector based on the data vector, the decision vector and the scalar gain vector. A back end module is configured to receive the revised data vector.

Systems and methods for gain compensation and re-timing in magnetic recording channels

A system and method are provided to detect defects in a data storage medium by sampling data read from the data storage medium. Time referenced samples of data read from the data storage medium are equalized to mediate the effects of channel noise and the equalized samples are decoded by a decoder, such as a Viterbi decoder. The decoded signal is then reconstructed through a reconstruction filter to approximate the equalized signal. The equalized data signal and the reconstructed data signal are then combined and compared in a bit-by-bit deconstruction scheme to determine, based on a variation between the signal elements, that a defect exists on the data storage medium. Additional action is then taken to mediate the effects of attempting to process corrupted data based on the defect by isolating the defective bit.

Defect detection design

Systems and techniques to interpret signals on a noisy channel are described. A described technique includes storing a group of signals including a filtered digital signal and one or more previous signals, the filtered digital signal being based on an analog signal; interpreting the filtered digital signal as first discrete values; determining whether the first discrete values are adequately indicated based on a result of the interpreting; initiating a retry mode when the first discrete values are not adequately indicated; producing, in the retry mode, a new signal, the new signal being determined based on an average of at least a portion of the group of signals; interpreting, in the retry mode, the new signal as second discrete values; and determining whether the second discrete values are adequately indicated based on hard decisions indicated by the new signal and hard decisions indicated by the filtered digital signal.

Averaging signals to improve signal interpretation

A receiver for a hard disk drive system includes an analog front end module configured to sample a read-back signal and to output a digital read-back signal. An equalizer module is configured to generate a data vector based on the digital read-back signal. A detector module is configured to generate a decision vector based on the data vector. A re-timing module is configured to generate a first revised data vector based on the data vector and the decision vector. The re-timing module re-samples a plurality of samples in the data vector in a non-sequential time order to generate the first revised data vector. An inter-track interference (ITI) cancellation module is configured to remove ITI from the first revised data vector and to generate a second revised data vector.

Growing community of inventors

Sunnyvale, CA, United States of America

Hongxin Song