Seagate Technology Incorporated

Maxtor Corporation

Quantum Corporation

Mathew Power Vea

Ara Patapoutian

Michael D Leis

Richard M Ehrlich

Bruce Douglas Buch

Kevin Dean Fisher

James A Henson

William R Akin, Jr

David Erich Tetzlaff

Philip L Steiner

Jon Karsten Klarqvist

Nan-Hsiung Yeh

Saeed Asgari

George Iszlai

A data signal comprising an even component and an odd component with differing amplitudes is received at a main automatic gain controller (AGC). The even component is adjusted by a first interleaved AGC and the odd component is adjusted by a second interleaved AGC such that even and odd component amplitudes are substantially equal. Amplitude adjusted even and odd components are recombined to define a data signal with components having substantially equal amplitudes. The even and odd components can be generated by a read transducer moving relative to a magnetic storage medium comprising tracks defined by discrete and spaced-apart recording bits arranged in an interspersed pattern. A read channel separates the data signal into even and odd samples such that a gain can be independently adjusted for each of the even and odd samples to compensate for asymmetry between the even and odd samples.

Interleaved automatic gain control for asymmetric data signals

This disclosure is related to measurement of latency in data paths. A latency measurement may be accomplished by calculating a roundtrip write-to-read latency based on generating a write signal and receiving a read signal approximately simultaneously. The read signal may be based on a coupling between a write element and read element. A device setting may then be adjusted based on the calculated roundtrip write-to-read latency. Further, a read/write mechanism that is used to write user data to and read user data from a data storage medium may be used to determine the roundtrip write-to-read latency. Even further, the roundtrip write-to-read latency may be determined in real-time as the data storage device is in operation.

Measurement of latency in data paths

A technique is described for write synchronization phase calibration for storage media (e.g., bit patterned media). In one embodiment, a calibration write clock signal may be generated at a frequency offset from a nominal dot frequency of a bit patterned storage media. A periodic signal that was written to the media synchronous to the calibration write clock signal may then be read and mixed with a reference periodic signal at the nominal dot frequency to obtain a difference signal. This difference signal may be demodulated to determine a phase correction for write synchronization to the media.

Write synchronization phase calibration for storage media

A method and apparatus for measuring latency in a communication path is provided. The technique includes driving a signal such as a square wave on the communication path, such as a write path such that it travels around the write-read path, and sensing a returned signal at one end of the write-read path. A square wave signal corresponding to the square wave driven on the write path is delayed by a predetermined phase thus generating a delayed signal. The returned signal and the delayed signal are mixed, producing a mixed signal. The mixed signal is integrated to obtain an integrated output. The phase by which the delayed signal is shifted is successively adjusted. Returned signals are mixed with such delayed signals until the integrated output is equal to zero. The phase shift amount that results in a nulled integrated output, less a quarter cycle of the square wave, is equal to the round trip latency of the write-read path.

Measurement of round trip latency in write and read paths

A method of defining such a storage format in multiple data storage devices, each data storage device having a plurality of storage media and a plurality of corresponding data transducer heads, each transducer head for recording on and playback of information from a corresponding storage medium in at least one zone, wherein each zone includes a plurality of concentric tracks for recording on and playback of information. The method includes the steps of: selecting a plurality of said data storage devices; for each selected data storage device, measuring a record/playback performance capability of each head at one or more read/write frequencies per zone; based on said performance capability measurements, generating storage density distributions corresponding to at least a number of the heads in said selected data storage devices; selecting a group of read/write frequencies for said multiple data storage devices, two or more frequencies for each zone, based on said storage density distributions; and assigning one of said read/write frequencies to each head based on performance capability of that head.

Per zone variable BPI for improving storage device capacity and yield

A magnetic disk drive data storage disk defines recording tracks divided into data sectors by narrow servo spokes. A data sector lying between servo spokes is recorded with user data encoded in accordance with a code having a predetermined distance and user data code rate. Each servo spoke of the recording area has at least one servo information field encoded in a wide bi-phase code pattern. The disk drive further includes a synchronous sampling data detection channel having a data transducer head positioned by a servo-controlled actuator over the recording track, a preamplifier for receiving electrical analog signals magnetically induced by the data transducer head from flux transitions present in at least the servo information field, a digital sampler for synchronously sampling the electrical analog signals to produce digital samples, and wide bi-phase decoding circuitry coupled to receive digital samples from the synchronous sampling data detection channel for decoding the wide bi-phase code pattern.

Synchronous detection of wide bi-phase coded servo information for disk drive

Disclosed is a method and apparatus for increasing the reliability of a disk drive. A block of information is read from a storage medium to provide a first sample, which is stored. The method determines whether an uncorrectable error occurred during the reading, and when the error is determined to have occurred, the block of information is reread from the storage medium to provide an averaged sample, and the average sample is decoded. Further disclosed is a storage unit, which includes a reader for reading a block of information from a storage medium to provide a first sample and for storing said first sample. An error determining mechanism determines whether an uncorrectable error occurred during the reading and issues a command to the reader to re-read the block of information to provide a second sample when the uncorrectable error is determined. A processor receives and averages the first sample and the second sample and produces an averaged sample. A decoder decodes the average sample.

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Shrewsbury, MA, United States of America

Mathew Power Vea