Radial Incoherence Compensation in Magnetic Storage Servo Tracks
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Solution Overview
Problem
In magnetic recording, radial incoherence in servo data between adjacent tracks leads to asynchronous writing, causing bit edges on adjacent tracks to misalign due to ambient vibrations and temperature variations, which is undesirable in high areal density storage systems.
Innovation Solution
Writing servo data with orthogonal repeating patterns on adjacent tracks, determining their relative phase, and adjusting write delays to synchronize data writing, ensuring that bit edges align across tracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If servo data are written using conventional methods, then writing process is simple, but radial incoherence causes bit edges on adjacent tracks to misalign
Solution Approach 1:
The patent applies preliminary action by measuring the radial incoherence between adjacent tracks during the servo writing process and storing these measurements. This preliminary measurement and storage of incoherence data enables subsequent compensation during data writing operations, achieving bit edge alignment without adding complexity to the actual data writing process.
2Manufacturing precision
If adjacent tracks are written asynchronously, then writing process is faster, but data alignment between tracks deteriorates
Solution Approach 1:
The system performs preliminary measurement of radial incoherence during servo writing and stores these measurements for later use. This allows asynchronous writing to proceed at high speed while the stored incoherence data enables post-processing compensation to achieve precise data alignment between tracks.
3Manufacturing precision
If radial incoherence is not compensated, then system operation is simpler, but storage density improvement is limited
Solution Approach 1:
The patent measures and stores radial incoherence data during the servo writing phase as a preliminary action. This stored information is then used to compensate for alignment errors during subsequent high-density data writing operations, enabling improved areal density while keeping the operational complexity manageable through automated compensation.
Data Source
AI summary
A method of operating or calibrating a storage device having a storage medium platter includes writing servo data to the storage medium platter, where the servo data include, for each track on the storage medium platter, a servo sync mark, and a repeating pattern. For each pair of adjacent tracks on the storage medium platter, the repeating patterns, which may be orthogonal, are compared to determine relative phase of the repeating patterns on adjacent tracks. The relative phase for each pair of adjacent tracks is recorded. In another calibration method, first and second repeating patterns may compared to determine whether relative phase of the first and second repeating patterns exceeds a threshold, in which case the second servo data are erased, new second servo data are written, and the comparing and erasing are repeated until the relative phase of the first and second repeating patterns is less than the threshold.