Inter-Track Interference Filter for Data Storage Read Channels
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Solution Overview
Problem
As data tracks in disk drives are squeezed closer together, inter-track interference (ITI) distorts the read signal, reducing the accuracy of data detection and making it challenging for existing systems to reliably read data from target tracks.
Innovation Solution
Implementing an ITI filter with a transfer function that attenuates high or low frequency noise from equalized samples, depending on the nature of the ITI, to generate ITI attenuated samples that improve data detection accuracy by subtracting noise components using high or low pass filters, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If data tracks are squeezed closer together to increase recording density, then storage capacity is improved, but inter-track interference distorts the read signal and reduces data detection accuracy
Solution Approach 1:
An ITI filter is introduced as an intermediary component between the equalizer and the data detector. This filter processes the read signal to attenuate inter-track interference components, allowing accurate data detection even when tracks are densely packed. The filter acts as a mediator that removes harmful interference while preserving useful signal information.
Solution Approach 2:
The patent applies parameter changes by adjusting the transfer function characteristics of the ITI filter to match the specific interference patterns caused by densely packed tracks. The filter coefficients and frequency response are optimized to target and attenuate ITI at specific frequencies while maintaining signal integrity, thereby enabling accurate detection at higher recording densities.
2Measurement precision
If inter-track interference is attenuated to improve data detection accuracy, then measurement precision is improved, but device complexity increases due to additional filtering stages
Solution Approach 1:
The ITI filter is merged with the existing equalizer structure in the read channel, combining multiple functions into a unified processing stage. This integration approach attenuates inter-track interference while minimizing the increase in device complexity by sharing computational resources and processing stages rather than adding completely separate filtering systems.
Data Source
AI summary
A data storage device is disclosed comprising a head actuated over a disk. A read signal from the head is sampled to generate signal samples, and the signal samples are filtered with an equalizer filter to generate equalized samples. The equalized samples are filtered with an inter-track interference (ITI) filter to generate ITI attenuated samples, and a data sequence is detected based on the ITI attenuated samples. In one embodiment, the ITI filter comprises a transfer function:1−HPF(ek)and in another embodiment the ITI filter comprises a transfer function:1−LPF(ek)where ek represents a noise sequence in the equalized samples, HPF represents a high pass filter operating on ek, and LPF represents a low pass filter operating on ek.