Storage Media Defect Detection Using ADC Signal Analysis
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Solution Overview
Problem
Current defect scanning techniques in storage media, such as hard disk drives, are inefficient due to limited resolution, requiring peak samples for detection, and failing to identify defects before timing acquisition, leading to incomplete defect mapping and increased detection time.
Innovation Solution
A system that computes amplitude, DC component, and phase using ADC samples, allowing for simultaneous detection of various defect types without requiring peak samples or timing acquisition, using accumulators to average these components and compare them to programmable thresholds for defect detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If typical defect scanners are used to detect defects, then defect locations can be identified, but the resolution is limited to sector level and the entire sector must be unused even if the defect is much smaller
Solution Approach 1:
The patent segments the storage media into smaller detectable units by analyzing individual sample points rather than requiring peak samples. This allows defect localization at a finer granularity than sector level, enabling precise mapping of defect locations without wasting entire sectors. The segmentation of the signal into discrete samples that can be processed independently facilitates higher resolution defect mapping.
2Measurement precision
If peak samples are required as input for defect detection, then defect locations can be determined, but timing acquisition must be performed first which takes additional time and requires a timing loop
Solution Approach 1:
The patent performs preliminary processing of all samples including computing amplitude, DC component, and phase for every sample point before defect detection. This preliminary computation of fundamental signal characteristics for all samples eliminates the need for separate timing acquisition loops, as the defect detection can directly utilize these pre-computed values from any sample without requiring peak sample identification.
3Reliability
If peak samples are required for defect detection, then defects can be detected, but defects occurring before timing acquisition (e.g., in preamble or beginning portion) are not detected
Solution Approach 1:
The patent computes amplitude, DC component, and phase for all samples including those in the preamble and beginning portions before defect detection. This preliminary processing ensures that no samples are excluded from analysis, allowing defects in the preamble or early portions of the signal to be detected without requiring timing acquisition to occur first.
4Reliability
If typical defect scanning techniques are used, then defect maps can be created, but the process is inefficient and requires additional timing loops
Solution Approach 1:
The patent merges multiple processing steps into a single efficient workflow by computing amplitude, DC component, and phase for all samples in one pass, then performing defect detection using these pre-computed values. This consolidation eliminates the need for separate timing acquisition loops and multiple processing passes, significantly improving scanning speed while maintaining defect map accuracy.
Solution Approach 2:
The patent maintains continuous useful action by processing all samples continuously without interruption for timing acquisition. The defect detection process operates continuously on pre-computed sample characteristics, eliminating idle time associated with timing loops and ensuring that every sample contributes to defect detection without interruption.
Data Source
AI summary
Detecting a defect on a storage device is disclosed. Detecting includes receiving a signal read from a storage device, sampling the signal to obtain a set of signal samples, wherein the sampling starts at an arbitrary time, computing a defect value for a defect type using the set of signal samples, comparing the defect value with a threshold associated with the defect type, determining whether there is a defect of the defect type based at least in part on the comparison, and in the event that a defect is detected, outputting an indication associated with the defect.