Disk Controller Subtrack Synchronization for Signal Interference
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Solution Overview
Problem
In magnetic disk apparatuses, increasing recording density leads to interference between symbols, degrading read signal quality due to the difficulty in suppressing signal degradation while improving recording density with existing two-level magnetization methods.
Innovation Solution
Implementing a disk apparatus capable of recording three signal levels (+1, 0, -1) by using two subtracks with synchronized phases, where the controller corrects displacement between write positions in real-time using feedback from read signals to maintain optimal recording quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If recording density on the disk medium is increased, then the storage capacity is improved, but interference between symbols occurs causing degradation of read signal quality
Solution Approach 1:
The track is divided into two subtracks (first subtrack and second subtrack) that are written in parallel. Each subtrack carries a portion of the data stream, allowing the recording density to be increased while maintaining signal quality through the combined output of both subtracks. The read head reads from both subtracks simultaneously and combines the signals to recover the original data.
Solution Approach 2:
A controller acts as an intermediary that manages the writing process to both subtracks. It performs write equalization and timing adjustment to ensure that data is written to both subtracks with proper synchronization, preventing symbol interference while maintaining high recording density.
2Quantity of substance
If two subtracks are used to increase recording density, then storage capacity is improved, but displacement between write positions in subtracks causes deterioration of three level signal quality
Solution Approach 1:
The system employs feedback mechanisms where the controller monitors the write positions in both subtracks and adjusts timing accordingly. Read signals are used to detect position displacement, and this information feeds back to the controller which then corrects the write timing for subsequent operations, maintaining precise alignment between subtracks.
Solution Approach 2:
The write timing for each subtrack is made dynamic rather than fixed. The controller adjusts the write timing in real-time based on detected position displacement, allowing the system to adapt to variations in write position and maintain optimal alignment between the two subtracks throughout the recording process.
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 enhances recording density and suppresses symbol interference, improving the bit error rate and overall recording quality by synchronizing write bit positions across subtracks.
Implementation Method 1
the value of a write bit is represented by a direction of magnetization on a disk medium
Data Source
AI summary
According to one embodiment, there is provided a disk apparatus including a disk medium and a controller. The disk medium is able to store a signal with three levels in a track. The track includes a first subtrack and a second subtract. The second subtrack is adjacent to the first subtract. The controller performs a first operation based on a selected level among the three levels, a first bit written in the first subtract corresponding to the selected level, and a second bit written in the second subtrack corresponding to the selected level. The first operation is an operation to correct displacement between a write position of a third bit in the first subtrack and a write position of a fourth bit in the second subtrack in a circumferential direction of the disk medium.