University System of Maryland

National Security Agency

Chun Tse

Isaak D Mayergoyz

Charles S Krafft

Dragos I Mircea

A system () and method for high-speed massive magnetic imaging on a spin-stand () is provided. The system () includes a spin-stand system () for driving a rotational spindle () to which a magnetic hard disk () is mounted. A magnetic read head () reads data from disk () and is in electrical communication with a universal head preamplification board (). The universal head preamplification board () outputs readable voltage signals which are transmitted to an oscilloscope () for displaying a read-back voltage display (). The signals are processed by a processing means () to generate scanned image data () on a display means. The display signals () are utilized to calibrate the magnetically read data to account for the eccentricity of the hard disks with respect to the center of rotation of the spin-stand spindle. Whole tracks of hard disk data can be imaged through the process of 'track-centering' and 'track-following'. An alignment algorithm is used to align the magnetically read data to compensate for the instability of the triggering signal.

System and method for high-speed massive magnetic imaging on a spin-stand

In recovering data originally written on a carrier of magnetic media after a catastrophic failure, data may be read without prior knowledge of the write channel by which the data was originally written and in the presence of intersymbol interference of the readback signal. This is accomplished by forming an image of the spatial response function of the magnetoresistive transducer used to recover the data and by forming an image of the raw data read from the carrier of magnetic media by the magnetoresistive transducer for which the response function has been characterized. An image of the distribution of virtual magnetic charge on the carrier of magnetic media is obtained through deconvolution of the image of the response function of the magnetoresistive transducer and the raw readback signal. The readback signal corresponding to the data originally written on the carrier of magnetic media is then recovered by spatial differentiation of the image of virtual magnetic charge. Further improvement in image quality of the resulting image is accomplished through a noise reduction technique such as by the application of an arctangent function to the data prior to differentiation.

Growing community of inventors

Beltsville, MD, United States of America

Chun Tse