Sequence Detector Compensating Inter-Track Interference
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Solution Overview
Problem
As data tracks on disk storage devices are squeezed closer together to increase capacity, they induce intertrack interference (ITI) in read signals, making it challenging to accurately detect data sequences within a single revolution, leading to reduced data recovery efficiency and increased revolutions required for accurate data retrieval.
Innovation Solution
Employing a trellis type sequence detector that accounts for intertrack interference by using expected samples from adjacent data tracks to compute branch metrics, allowing for accurate detection of data sequences during a single disk revolution through the use of DTI and ITI trellis type sequence detectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If data tracks are squeezed closer together to increase capacity, then storage density is improved, but intertrack interference increases making data detection more difficult
Solution Approach 1:
The patent uses the known data sequence from one track to compensate for intertrack interference in adjacent tracks. The interference that was previously harmful is now converted into useful information by using the detected sequence from track N to improve detection accuracy in track N+1, effectively turning the interference problem into a solution through predictive compensation.
Solution Approach 2:
The system implements feedback by using the detected data sequence from a previously read track to generate expected samples that are fed into the sequence detector for the current track. This feedback loop allows the detector to compensate for intertrack interference by comparing actual read samples against expected samples derived from adjacent track data.
2Device complexity
If traditional sequence detectors are used without intertrack interference compensation, then device complexity is kept simple, but data detection accuracy deteriorates due to intertrack interference
Solution Approach 1:
The patent performs preliminary detection of data sequences in adjacent tracks before using that information to detect the current track. By pre-obtaining the data sequence from track N and converting it to expected samples before reading track N+1, the system prepares compensation information in advance, enabling more accurate detection without requiring complex real-time interference cancellation hardware.
3Measurement precision
If multiple revolutions are required to accurately recover data due to intertrack interference, then detection accuracy can be improved through multiple readings, but productivity decreases
Solution Approach 1:
The patent performs preliminary detection and conversion of adjacent track data to expected samples during the same disk revolution in which the current track is being read. This allows intertrack interference compensation to be applied within a single revolution rather than requiring multiple revolutions, thereby maintaining high data throughput while achieving accurate detection.
Data Source
AI summary
A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of data tracks. A first data track is read to generate a first read signal, the first read signal is sampled to generate first read signal samples, a first data sequence is detected based on the first read signal samples, and the first data sequence is converted into corresponding first expected samples. A second data track adjacent the first data track is read to generate a second read signal, the second read signal is sampled to generate second read signal samples, and a second data sequence is detected based on the second read signal samples and the first expected samples.