Split Burst Servo Demodulation for Accurate Head Positioning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional data storage devices face challenges in accurately positioning heads due to servo pattern distortions caused by laser mode hop, leading to issues like track squeeze and repeatable runout errors, and require complex calculations for asynchronous sampling timing phase error correction.
Innovation Solution
Implementing read/write channel circuitry that performs asynchronous demodulation of split null burst signals, generating radial position signals directly, thereby reducing hardware requirements and processing time, and mitigating servo pattern distortions through the use of split null burst servo patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional servo pattern demodulation is used, then head positioning can be achieved, but positioning accuracy deteriorates due to servo pattern distortions caused by laser mode hop
Solution Approach 1:
The servo burst pattern is segmented into multiple samples taken at different asynchronous time points. By dividing the demodulation process into discrete sampling events rather than continuous synchronous sampling, the system can compensate for timing variations caused by laser mode hop, thereby maintaining positioning accuracy despite servo pattern distortions.
2Measurement precision
If synchronous sampling with complex phase error correction is used, then positioning accuracy can be maintained, but device complexity increases
Solution Approach 1:
The patent replaces the complex mechanical/synchronous sampling system with an asynchronous sampling approach. Instead of using precise timing synchronization and complex phase error correction calculations, the system uses simpler asynchronous sampling with modified demodulation mathematics, reducing computational complexity while maintaining positioning accuracy.
3Productivity
If asynchronous sampling is implemented, then processing speed can be improved, but measurement precision deteriorates without proper correction
Solution Approach 1:
The patent changes the fundamental parameter of sampling timing from synchronous to asynchronous. By modifying the demodulation mathematics to accommodate asynchronous sampling intervals and using weighted combination of multiple asynchronous samples, the system achieves both improved processing speed (no complex phase correction needed) and maintained positioning accuracy (through mathematical compensation).
Data Source
AI summary
Various illustrative aspects are directed to a data storage device, comprising one or more disks; an actuator mechanism configured to position one or more heads proximate to a corresponding disk surface of the one or more disks; and one or more processing devices. The one or more processing devices comprise control circuitry which comprises an asynchronous demodulation module. The asynchronous demodulation module is configured to: receive demodulated split null burst signals based on the selected head reading a first set of bursts and a second set of bursts in a split burst servo pattern of the corresponding disk surface; and output, based on the demodulated split null burst signals, a radial position signal, indicative of a radial position of the selected head