Inter-Track Interference Cancellation in Magnetic Storage Read Channels
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Solution Overview
Problem
As storage media capacities increase, inter-track interference (ITI) becomes significant due to closer data tracks, leading to data corruption and system latency in magnetic storage devices, as existing methods for ITI cancellation require seeking adjacent tracks and waiting for media rotation, introducing latency in reading data.
Innovation Solution
A method is introduced where a read channel reads sectors from a desired track, decodes them, and if incorrect, estimates and subtracts ITI from adjacent tracks, providing updated sector data through an ITI canceller, which replays the ITI-cancelled data for further decoding, reducing latency by performing ITI cancellation in parallel with read head positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ITI cancellation is performed by seeking to adjacent tracks and waiting for media rotation, then ITI can be detected and cancelled, but system latency increases significantly
Solution Approach 1:
The patent performs ITI cancellation using data that is already available in the buffer from previously read sectors, eliminating the need to wait for media rotation to adjacent tracks. The ITI canceller processes interference from adjacent tracks using previously buffered data, allowing parallel processing and significantly reducing latency.
Solution Approach 2:
The patent maintains continuous data flow by buffering sectors before decoding and performing ITI cancellation on buffered data while the read head continues to position for the next read operation. This eliminates idle waiting time and maintains continuous useful action in the data recovery process.
2Quantity of substance
If storage density is increased by placing tracks closer together, then storage capacity increases, but inter-track interference becomes more significant
Solution Approach 1:
The patent converts the harmful ITI signal from adjacent tracks into useful information by reading and buffering data from adjacent tracks, then using this buffered adjacent track data to estimate and cancel ITI from the desired track. The interference signal becomes the key to removing interference.
Solution Approach 2:
The patent introduces an ITI canceller as an intermediary component that processes data from adjacent tracks and subtracts estimated ITI from the desired track data. This intermediary component enables high-density storage by actively compensating for the interference that would otherwise prevent reliable data recovery.
3Device complexity
If ITI cancellation is performed sequentially after reading desired track, then processing is simple, but data recovery latency increases by approximately 2 disk revolutions
Solution Approach 1:
The patent performs preliminary buffering of sectors from adjacent tracks before ITI cancellation is needed. The buffer stores adjacent track data in advance, allowing the ITI canceller to immediately process interference cancellation without waiting for media rotation, reducing latency from 2 disk revolutions to minimal processing time.
Solution Approach 2:
The patent adds a time dimension to the processing by overlapping operations: while the read head positions for the next track read, the ITI canceller processes current data using previously buffered adjacent track data. This dimensional change in processing timing eliminates sequential waiting.
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 effectively cancels ITI, reducing data recovery latency by approximately 2 disk revolutions and improving data integrity by estimating and subtracting interference from adjacent tracks without waiting for media rotation, thus enhancing storage device performance.
Implementation Method 1
In read mode, as the magnetic storage surface moves across the gap in the head, the magnetic field of the storage surface is detected, and a voltage is induced in the head.
Implementation Method 2
Digital data is written to the storage media in a predetermined format using a write head that induces a magnetic field with sufficient amplitude to record on the magnetic material of the storage device.
Data Source
AI summary
Described embodiments provide a method of cancelling inter-track interference (ITI) from one or more sectors read from a desired track of a storage medium. A road channel reads sectors in a desired track of the storage medium. A decoder of the read channel decodes the read sectors, and if the read sectors are incorrectly recovered from the storage medium, selected sectors of a first adjacent track and a second adjacent track are read. An ITI canceller of the read channel estimates ITI in the read sectors of the desired track corresponding to the selected sectors of each adjacent track and subtracts the estimated ITI of each adjacent track from the data for the sectors of the desired track, providing updated sector data. The ITI cancelled data is replayed to the decoder, which decodes the ITI cancelled data and provides the decoded ITI cancelled data as output of the read channel.