Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Reexamination Certificate
2005-04-19
2005-04-19
Neyzari, Ali (Department: 2655)
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
C360S078060, C370S209000, C375S309000
Reexamination Certificate
active
06882604
ABSTRACT:
The invention is a modulation system that encodes symbols in accordance with a modulation code which, for a given communications channel, produces a signal that at the decoder includes maximized sample timing information in each encoded symbol. For systems that use PLLs to control a sample timing clock, the sample timing information is the average or squared slope. The modulation code used for a given system is selected based on the target response h(x) of the associated communications channel, such that h (x)*rkexceeds a predetermined threshold value, where “*” represents convolution and rkis a modulation code symbol. To reduce the bit overhead, or code rate, the inventive modulation system provides more modulation code symbols at the start of a data block, or sector, when system jitter is expected to be relatively high in response, for example, to the movement of a read head. The system then includes fewer modulation code symbols later in the block, when the system jitter associated with a read or receive operation is reduced. The system thus provides sufficient timing information to minimize PLL jitter.
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McEwen Peter
Patapoutian Ara
Cesari and McKenna LLP
Maxtor Corporation
Neyzari Ali
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