Split-Sector FIR Recovery for ISI-Free Data Readback
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Solution Overview
Problem
Split sectors in hard disk data storage cause fragmentation of user data, leading to discontinuities in the data stream during readback, which complicates the decoding process and results in increased bit error rates due to inter-symbol interference (ISI) from system information inserted between data segments.
Innovation Solution
A formatter block is introduced to stitch FIR samples together into a continuous stream, removing the need for the decoder to know the data format and addressing discontinuities caused by split sectors, thereby recovering the data as if no split existed, by removing the ISI contribution from split-mark data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If split sectors are used to store data between servo wedges, then data storage flexibility is improved, but data stream continuity deteriorates due to fragmentation
Solution Approach 1:
A formatter block is introduced as an intermediary component between the read channel and the decoder. This formatter stitchesth FIR samples together into a continuous stream, removing system information (second syncmark) that was inserted between data segments, and formats the data into logical sectors before decoding. This mediator resolves the discontinuity caused by split sectors while maintaining the flexibility of storing data between servo wedges.
2Manufacturing precision
If second syncmark is inserted to mark split sectors, then data segmentation is improved, but bit error rate increases due to inter-symbol interference
Solution Approach 1:
The formatter block extracts and removes the second syncmark (system information) that was inserted to mark split sectors. By taking out this syncmark data from the FIR sample stream, the formatter eliminates the source of inter-symbol interference while preserving the necessary data segmentation information through proper formatting into logical sectors before decoding.
3Measurement precision
If decoder knows data format on media, then decoding accuracy is improved, but device complexity increases
Solution Approach 1:
The processing system is segmented into distinct functional blocks: a read channel that reads FIR samples, a formatter block that processes and formats the data by removing syncmarks and stitching samples, and a decoder that receives pre-formatted data. This segmentation allows the decoder to focus solely on decoding without needing to know the physical data format, while the formatter handles format-related processing.
4Reliability
If FIR samples are stitched into continuous stream, then data reliability is improved, but processing memory requirements increase
Solution Approach 1:
The formatter block performs preliminary actions of stitching FIR samples and removing syncmarks before the data reaches the decoder. By preparing the continuous data stream in advance, the formatter eliminates the need for the decoder to store and manage split sector information, actually reducing overall memory requirements while improving data reliability through proper formatting.
Data Source
AI summary
Reproduction of encoded data which includes a split-mark. FIR data corresponding to split-mark and FIR data affected by the split-mark due to inter-symbol-interference are identified. FIR data corresponding to the split-mark is removed from the received FIR data. Recovered data is created by removing incorrect inter-symbol-interference from the FIR data due to the split-mark, and adding correct inter-symbol-interference from codeword bits. The recovered data is stitched together with data unaffected by split-mark data.