Seagate Technology Incorporated

Robert E Kost

Bernardo Rub

Kinhing Paul Tsang

Kenneth R Burns

Hamid R Shafiee

Jian-Gang Zhu

A system determines bit error rate in a sampled data system having a disc formed of a magnetic medium and a data head for writing data on the disc and retrieving data from the disc. A pattern is written on the disc, which includes isolated instances associated with a predetermined event. The pattern is retrieved from the disc and the isolated instances are combined to obtain a representative instance having a reduced media noise component. The representative instance is combined with each, of the isolated instances to obtain noise sequences. An autocorrelation component is obtained based on the instances read from the disc and the noise sequences. A channel filter is developed having an impulse response based on the representative instance and based on the channel requirements for a predetermined channel model. A representative instance is passed through the filter to obtain a filter output sample, and an error value indicative of the bit error rate is determined based on the filter output sample and the autocorrelation component.

Method and apparatus for determining bit error rate in a sampled data system without requiring read channel circuitry

The present invention provides sequence detection which takes into account amplitude and/or time distortions caused by neighboring magnetization regions on the magnetic medium, wherein the distortions in one magnetization region are caused by the closeness of neighboring magnetization transitions on one or both sides thereof. The sequence detection according to the present invention provides an extended state diagram to include the effects of leading and/or trailing magnetization transitions. More particularly, it has been found that accounting for the effects of trailing transitions requires an increase in the number of states in the state diagram used to form the Viterbi detector. Leading transitions are neutralized by increasing the number of branches between states in the Viterbi detector. Increasing the number of branches instead of states keeps the complexity low and thus saves hardware and associated costs.

Branch metric compensation for digital sequence detection

A detector in an informational handling system and a method of detection is provided. An input circuit is used to receive an input signal. A second circuit determines boundaries based on the input signal. However, at least two of the boundaries specified by the second circuit are monotonically related to each other. The detector can be implemented in a magnetic disc drive. A read circuit is operably coupled to the disc to read data stored on the disc. The read circuit includes an input circuit, a boundary calculation circuit, and a logic circuit operably coupled to one another. The input circuit serves to receive the data and provide an input to the boundary calculation circuit. The boundary calculation circuit calculates several boundaries based on the input. At least two of the boundaries are monotonically related. The boundary circuit provides an output to the logic circuit which provides a binary decision.

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Minneapolis, MN, United States of America

Robert E Kost