Dibit Pulse Extraction Using Symbol-Rate Sampling
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Solution Overview
Problem
Current dibit pulse extraction techniques for magnetic hard-disk drives (HDDs) require high sampling clocks, making them impractical and costly to implement, as they need to identify and minimize nonlinear distortions in read/write channels to maintain performance and data storage density.
Innovation Solution
A receiving device, such as an HDD, estimates an oversampled dibit pulse response using a data acquisition circuit and a dibit pulse estimation circuit that operates at the read channel symbol rate, with phase rotation and finite impulse response filters to eliminate phase shifts without increasing sampling frequency or perturbing the closed-loop read circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current dibit pulse extraction techniques are implemented, then nonlinear distortions can be identified and minimized, but very high sampling clocks are required making implementation impractical and costly
Solution Approach 1:
The patent changes the sampling parameters by operating at the normal symbol rate rather than requiring very high sampling clocks. Phase rotation and finite impulse response filtering are applied to process the normally-sampled data to extract oversampled dibit pulse response information, thereby achieving accurate measurement without complex high-speed sampling hardware
Solution Approach 2:
The patent replaces the mechanical/apparatus-based solution of using external high-speed sampling instruments with a signal processing approach using phase rotation and FIR filtering. This substitution eliminates the need for expensive external high-speed instrumentation and makes the system self-sufficient using its existing read channel infrastructure
2Measurement precision
If external high-speed instrumentation is used to measure nonlinear distortions, then measurement accuracy is achieved, but cost and implementation time increase significantly
Solution Approach 1:
The patent enables the HDD read channel to perform its own self-diagnosis and measurement of nonlinear distortions using its existing infrastructure. The dibit pulse estimation circuit uses the read channel's own sampled data, phase rotation capability, and FIR filter to extract oversampled pulse response, eliminating the need for external measurement instruments and reducing implementation cost and time
Solution Approach 2:
The patent introduces phase rotation and FIR filtering as intermediary signal processing steps that transform normally-sampled data into oversampled dibit pulse response information. These intermediaries enable accurate measurement without requiring actual high-speed sampling hardware, thereby reducing cost while maintaining measurement precision
3Measurement precision
If sampling frequency is increased to achieve oversampled dibit pulse response, then measurement resolution improves, but hardware complexity and cost increase
Solution Approach 1:
The patent performs preliminary phase rotation and FIR filtering on the normally-sampled data to pre-process it into a form that reveals oversampled dibit pulse response characteristics. This preliminary signal processing action achieves the resolution benefits of high-frequency sampling without actually requiring high-frequency sampling hardware
Data Source
AI summary
A receiving device may be configured to derive an oversampled dibit pulse response estimate using symbols sampled at substantially the read channel symbol rate of the receiving device. The receiving device may include a data acquisition circuit configured to digitize data derived from a memory medium, as well as a dibit pulse estimation circuit configured to estimate the oversampled dibit pulse response using symbols sampled at the read channel rate of the receiving device.