Pulse or digital communications – Receivers – Particular pulse demodulator or detector
Reexamination Certificate
2005-01-28
2008-10-21
Bayard, Emmanuel (Department: 2611)
Pulse or digital communications
Receivers
Particular pulse demodulator or detector
C375S263000
Reexamination Certificate
active
07440522
ABSTRACT:
A method of evaluating the quality of a read signal from the viewpoint of the detection margin of a Viterbi decoder in the PRML method in which a target signal level varies depending on the read signal, and an optical disc apparatus implementing the method. A method of evaluating the quality of a signal pattern comprising a combination of minimum run lengths from the viewpoint of edge shift, and an optical disc apparatus implementing the method. From the target signal level that varies depending on the read signal, a target signal is generated based on a decoding result, and an error target signal is generated in which the decoding result is edge-shifted. The signal quality is evaluated by calculating a Euclidean distance between these signals and the read signal. A virtual state that is not included in the Viterbi decoder and that is less than the minimum run length is defined, and a target signal level for the virtual state is generated using a target signal level table inside the Viterbi decoder, based on the concept of convolution. In this way, the signal quality can be evaluated by the same method as mentioned above even in cases where the pattern of a combination of the minimum run lengths has edge-shifted.
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Antonelli, Terry Stout & Kraus, LLP.
Bayard Emmanuel
Hitachi , Ltd.
Hitachi-LG Data Storage, Inc.
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