Mixed-Rate Servo Codeword Interleaving for Trellis Detection
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Solution Overview
Problem
Current data storage devices face challenges in accurately positioning the head over disk tracks due to limitations in servo sector encoding and decoding, which affects the precision of head movement and data access operations.
Innovation Solution
The implementation of a mixed rate codeword interleaving scheme, where a first codeword with a lower code rate is interleaved with a second codeword of higher code rate, enhances the accuracy of trellis detectors by improving decoding probability and reliability metrics, thereby refining head positioning and data access precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single high code rate codeword is used for servo data encoding, then the data transmission efficiency is improved, but the decoding reliability and head positioning precision deteriorate
Solution Approach 1:
The patent divides the single codeword into two separate codewords with different code rates. The first codeword uses a lower code rate (higher redundancy) for critical positioning data, while the second codeword uses a higher code rate for less critical data. This segmentation allows the system to achieve both high overall efficiency and high decoding reliability for critical operations.
Solution Approach 2:
Different parts of the servo data are encoded with different code rates according to their importance. The first codeword with lower code rate is applied to critical head positioning information that requires high decoding reliability, while the second codeword with higher code rate is applied to less critical data. This local differentiation of encoding quality optimizes both reliability and efficiency.
2Reliability
If a lower code rate codeword is used for critical positioning data, then the decoding reliability is improved, but the overall data transmission efficiency deteriorates
Solution Approach 1:
The patent changes the code rate parameter differently for different codewords. The first codeword uses a lower code rate parameter for critical data requiring high reliability, while the second codeword uses a higher code rate parameter to maintain overall transmission efficiency. This parameter differentiation resolves the contradiction between reliability and efficiency.
Solution Approach 2:
By segmenting the servo data into two codewords with different code rates, the patent allows critical positioning data to use lower code rate (higher reliability) while non-critical data uses higher code rate (higher efficiency), thus resolving the overall efficiency deterioration that would result from uniformly using lower code rate.
3Measurement precision
If redundant encoding is increased for head positioning data, then the head positioning precision is improved, but the servo sector capacity deteriorates
Solution Approach 1:
The patent applies different levels of redundancy (code rates) to different parts of the servo data. Critical head positioning information receives higher redundancy through the first codeword with lower code rate, improving positioning precision, while less critical data uses the second codeword with higher code rate, preserving overall servo sector capacity.
Solution Approach 2:
By segmenting servo data into two codewords, the patent concentrates redundancy resources on critical positioning data in the first codeword while maintaining higher efficiency in the second codeword. This selective redundancy application improves positioning precision without proportionally reducing overall servo sector capacity.
Data Source
AI summary
A data storage device is disclosed comprising a storage medium. First data is encoded into a first codeword, and second data is encoded into a second codeword, wherein a first code rate of the first codeword is less than a second code rate of the second codeword. The first codeword and the second codeword are interleaved to generate an interleaved codeword that is written to the storage medium.