Abstract:
A system provides two distinct solutions for encoding and decoding servo positioning data for a hard disk drive. A first solution includes: encoding each group of four bits of a pattern signal in a Matched Spectral Null (MSN) format through an intermediate rate {fraction (4/6)} code; providing a duplicated bit for each bit of the six bit code word obtained with the previous step. A second solution includes: encoding each group of four bit of the pattern signal adding a parity check bit as an intermediate rate null code; encoding each of the five bits using the biphase map. Both solutions include subsequently: reading a servo wedge information signal using a read and write channel of the hard disk drive; and using a trellis Partial Response decoding scheme matched to said encoded word for obtaining angular and radial information for the head positioning.
Abstract:
A method of storing a data file, particularly in the MPEG format and including a flow of different frames, comprises a protection system for the data file based on a parameter stored in the data file. Advantageously, the storage method comprises selectively protecting the frames by storing parameters that are associated with corresponding different frames whose values are selected to provide a playing quality level requested by an end user. Also, a method is provided for decoding a data file, particularly of the MPEG type and including a flow of different frames, wherein the data file is stored per above.
Abstract:
A method is provided for optimizing a PRML (Partial Response Maximum Likelihood) receiving channel for mass memory data receiving systems comprising an input receiving channel, a receiver placed downstream of the channel, a detector connected in cascade to the receiver, and a summing node being input both the receiver output through a delay line, and the output from the detector through an impulsive filter. The method includes performing an indirect estimate of the noise strength by filtering out the error sequence, i.e. the output signal from the summing node, through a filter, and selecting either the output from the summing node or the output from the filter to obtain an optimization parameter for feedback to the receiving system.
Abstract:
A method and apparatus for detecting and correcting errors in a magnetic recording channel of a mass storage system that combines a Soft Output Viterbi Algorithm SOVA, which has the capability of detecting the reliability of a discrete, equalized signal, and a post processor, which has the capability of detecting specific error events in said discrete, equalized signal, so as to correct error events and to generate an output bit stream.