Imation Corporation

Alan Olson

Denis J Langlois

Richard W Molstad

John R Bruss

Mark P Weber

Douglas K Hogue

Douglas W Johnson

Richard E Jewett

Eran Schul

Limiting the sound pressure level presented to the listener's ears by one or more headphones, using processing capabilities of a personal media device. Headphones, coupled to audio signals from a personal media device, include a sensor to measure the sound pressure level presented to the listener's ears, and provide that measure to the personal media device. The personal media device, optionally aided by one or more analog circuits, adjusts the audio signal so that the sound pressure level is maintained within a recommended range.

Sound pressure level limiting

Optimized sound waves presented to the listener by headphones, notwithstanding differences in ear geometry and headphone positioning. A test signal causes an acoustic sensor to receive sound waves actually formed in the listener's ear cavity. A response from the sensor is compared with an expected ear cavity transfer function, from which desired adjustments to the audio signal are determined. The audio signal might be received from an application program, calibrated by an interface software element, and adjusted thereby, before forwarding to the headphones. Calibration might be performed from when the headphones are positioned, or dynamically in response to changes in the transfer function.

Headphone response optimization

A flash memory based storage device may utilize magnetoresistive random access memory (MRAM) as at least one of a device memory, a buffer, or high write volume storage. In some embodiments, a processor of the storage device may compare a logical block address of a data file to a plurality of logical block addresses stored in a write frequency file buffer table and causes the data file to be written to the high write volume MRAM when the logical block address of the data file matches at least one of the plurality of logical block addresses stored in the write frequency file buffer table. In other embodiments, upon cessation of power to the storage device, the MRAM buffer stores the data until power is restored, after which the processor causes the buffered data to be written to the flash memory under control of the flash memory controller.

Flash memory based storage devices utilizing magnetoresistive random access memory (MRAM) to store control information facilitating wear leveling

Flash memory based storage devices utilizing magnetoresistive random access memory (MRAM) to store files having logical block addresses stored in a write frequency file buffer table

The disclosure describes a data storage system that includes a signal defect correction system for removing signal defects in magnetoresistive head playback signals. The signal defect correction system utilizes a matched finite impulse response (FIR) filter and digital signal processing algorithms. The matched FIR filter is designed with an impulse response that is the time reversed, complex conjugate of a signal defect model. The signal defect model is generated from a number of sample playback signals. The matched FIR filter is applied to the playback signal and digital signal processing techniques are applied to the filter response to detect a signal defect in the playback signal and estimate the amplitude and location of the signal defect. The signal defect model is retrieved from memory and applied to the playback signal using the amplitude and location estimates to substantially remove the signal defect from the playback signal.

Method and system for removing signal defects in MR head signals

Data storage tape comprises one or more data tracks and a servo band. The servo band stores a plurality of servo patterns within a servo frame to facilitate head positioning relative to the data tracks. Spacings between the servo patterns within the servo frame vary to encode information in the servo frame. A number of bits in the information is greater than a number of servo patterns within the frame. Servo patterns in different servo bands on the data storage tape may be different to provide band identification information. The different servo patterns of the different servo bands may allow lateral position calculations using the same formula for each servo pattern.

Servo pattern with encoded data

In general, the invention is directed to servo techniques that utilize servo patterns to facilitate head positioning relative to the data tracks. For example, the servo techniques may include a first series of servo patterns configured to allow calculation of a position error signal that substantially mitigates error resulting from a variation in velocity of the data storage tape during detection of the at least one of the servo patterns in the first series. The servo techniques may also include a second series of servo patterns interleaved within the first series of servo patterns in order to encode data. The encoded data may include linear position information. Embodiments may allow a data storage tape meeting a currently accepted data storage tape specification, e.g., an LTO Ultrium specification, to record data in a higher density than currently implemented with the specification.

Interleaved servo pattern

Techniques are described for accurately processing playback signals of time-based servo patterns recorded on a data storage medium. In particular, techniques are described for determining values for signal peaks within a playback signal of a time-based servo pattern by applying interpolation to data points in proximity to each of the signal peaks. At least three data points are identified in proximity to a desired peak to be detected within the playback signal. A value is calculated for the desired peak based on interpolation of the at least three data points. A playback signal of a time-based servo pattern may include a sequence of signal peaks. A time-based servo pattern may be detected based on lengths of time measured between consecutive peaks in the sequence of peaks. A position error signal (PES) may be generated based on the values calculated for each of the sequence of peaks.

Processing techniques for time-based servo patterns

The invention is directed to servo techniques that make use of sequences of servo marks, rather than individual marks for generation of position error signals. In particular, random or pseudo-random sequences of servo marks may be recorded on the medium in an overlapping fashion. For example, a first sequence of marks and a second sequence of marks may overlap in the servo track. The second sequence may be substantially non-correlated with the first sequence, and may be recorded in an offset location along the track relative to the first sequence. Different correlators can be used to detect the different sequences, and position error signals can be generated based on timings associated with the detection of the first sequence relative to the second sequence.

Sequenced time-based servo techniques

The invention provides techniques for verifying that a servo pattern has been properly recorded. For example, the amplitude of a signal corresponding to magnetic servo patterns can be detected and then compared to a threshold to determine whether the servo patterns were properly recorded. The signal strength may be determined for a servo band that includes multiple servo tracks. To enable this determination, a magnetic head may be designed to have sufficient width to enable the head to detect magnetic signal strength corresponding to more than one servo track.

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Cottage Grove, MN, United States of America

Alan Olson