Two-Stream Data Sequence Detection for Band-Limited ISI Channels
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Solution Overview
Problem
In magnetic storage systems, increasing data density leads to intersymbol interference (ISI) due to overlapping magnetic pulses, causing detection errors in band-limited channels.
Innovation Solution
A method involving two processing paths with equalization and noise predictive filtering to generate phase-shifted sample streams, which are then diversity combined to improve data sequence detection, using adapted filter coefficients for interpolation and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If data density is increased to improve storage capacity, then storage capacity is improved, but intersymbol interference occurs causing detection errors
Solution Approach 1:
The detection process is segmented into two parallel streams: a first stream that processes samples at the original sampling rate and a second stream that processes interpolated samples at a higher rate. This segmentation allows each stream to handle different aspects of the signal, with the first stream capturing dominant frequency components and the second stream capturing higher frequency components, thereby reducing intersymbol interference while maintaining high storage capacity
Solution Approach 2:
An interpolation filter is introduced as an intermediary component between the analog-to-digital converter and the detection circuitry. This interpolation filter generates additional sample points between original samples, creating a phase-shifted version of the sample stream. The interpolated samples serve as a mediator that provides additional information about the signal waveform, enabling more accurate detection and reducing ISI effects
2Device complexity
If traditional single-stream detection is used to maintain simple processing, then device complexity is low, but detection errors increase due to ISI
Solution Approach 1:
The detection system is divided into two parallel processing streams with distinct functions. The first stream uses a first interpolation filter and first detection circuit to process samples at the original rate, while the second stream uses a second interpolation filter and second detection circuit to process interpolated samples. This segmentation distributes the detection task across multiple specialized pathways, improving accuracy without requiring a single overly complex processing unit
Solution Approach 2:
The outputs from both processing streams are combined to form the final detection result. The first detection circuit produces detection results from original samples, while the second detection circuit produces results from interpolated samples. These results are merged through addition or other combination operations, combining the strengths of both streams to achieve superior detection accuracy while keeping individual stream complexities manageable
Data Source
AI summary
A method for data sequence detection includes generating a first sample stream, equalizing the first sample stream to generate a first equalized sample stream, and buffering the first equalized sample stream. The first sample stream is interpolated to generate a second sample stream. The second sample stream is equalized to generate a second equalized sample stream. In a first processing path, the samples of the buffered first equalized sample stream are filtered using a first noise predictive filter bank to generate a first set of noise sample streams. In a second parallel processing path, the samples of the buffered first equalized sample stream are interpolated using a second interpolation filter to generate an interpolated sample stream and the interpolated sample stream is filtered to generate a second set of noise sample streams. The first equalized sample stream and the second equalized sample stream are processed to generate adapted filter coefficients for the second interpolation filter. The first and second set of noise sample streams are diversity combined to generate a set of combined noise sample streams. A data sequence is detected using the set of combined noise sample streams.