Sync Mark Detection for Magnetic Storage
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Solution Overview
Problem
In magnetic storage systems, accurately locating the start of user data in each sector and detecting offtrack read head positions is challenging due to interference from neighboring tracks, leading to false sync mark detection and reduced accuracy in sector format identification and data retrieval.
Innovation Solution
The implementation of multiple alternating sync mark patterns, which are orthogonal and have high auto-correlation values, is used to differentiate sync marks in target tracks from those in neighboring tracks, reducing false detection and enabling accurate sync mark detection, offtrack position estimation, and sector format identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single sync mark pattern is used in magnetic storage systems, then the system structure is simple, but false detection from neighboring tracks occurs and accuracy is reduced
Solution Approach 1:
The sync mark detection function is segmented into multiple specialized detectors, each tuned to detect a specific sync mark pattern. This segmentation allows each detector to focus on one pattern type, improving detection accuracy while the collective system handles multiple patterns to prevent false detections from neighboring tracks.
Solution Approach 2:
Different sync mark patterns are assigned to different track types (e.g., even tracks vs. odd tracks, or different sector formats). This local quality differentiation ensures that the read channel expects the correct pattern for the current track, eliminating false detections from adjacent tracks with different patterns.
2Reliability
If multiple alternating sync mark patterns are used to reduce false detection, then false sync mark detection is reduced, but the complexity of the detection system increases
Solution Approach 1:
Multiple sync mark detectors are merged into a unified detection system with a single output interface. The comparator unit combines the outputs of all detectors to determine the final sync mark detection result, managing the complexity of multiple detectors through a centralized decision-making structure.
Solution Approach 2:
The comparator unit provides feedback by comparing the outputs of multiple detectors and using this comparison to make a reliable detection decision. This feedback mechanism ensures that even with multiple detectors, the system achieves high reliability by cross-validating detection results.
3Measurement precision
If multiple sync mark patterns are implemented, then sector format identification accuracy improves, but the processing complexity increases
Solution Approach 1:
The system performs preliminary detection of which sync mark pattern is present before proceeding to full data processing. This preliminary action allows the system to quickly identify the sector format based on the detected pattern type, enabling subsequent processing to be optimized for the specific format without requiring complex real-time analysis.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces false sync mark detection in neighboring tracks, improves the accuracy of locating the start of user data, and allows for efficient identification of sector formats and inverted polarity, enhancing data retrieval precision and power management by differentiating user data from flawscan fragments.
Implementation Method 1
passing a modulated electric current through the head assembly such that a corresponding magnetic flux pattern is induced in the storage medium
Implementation Method 2
the previously stored magnetic flux pattern induces a current in the head assembly that can be converted to the previously recorded digital data
Data Source
AI summary
A data processing system includes a number of analog to digital converters operable to sample analog signals obtained from a magnetic storage medium to yield digital signals, multiple sync mark detectors operable to search for a number of different sync marks in the digital signals, and a sync mark detector output comparator operable to compare an output of each of the sync mark detectors to identify detection errors.