Anti-Causal Noise Predictive Filter Circuit for Burst Error Reduction

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Solution Overview

Problem

Existing data processing systems face limitations in recovering originally written data due to media noise, particularly burst errors caused by long runs of bit periods, which are not effectively addressed by causal noise predictive filtering.

Innovation Solution

The implementation of anti-causal noise predictive filtering, which uses historical information including future noise samples to predict and filter out noise, balancing error locations across non-transitory runs, and incorporating a data detection algorithm like the maximum a posteriori or Viterbi algorithm, along with a data decoding algorithm such as Reed Solomon or low density parity check, to improve bit error rate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If causal noise predictive filtering is used, then the system can process data in real-time, but it cannot effectively address burst errors caused by long runs of bit periods

Engineering Contradiction:
Improveerror correction capabilityVSAvoidhandling of different noise patterns
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent inverts the traditional causal filtering approach by implementing anti-causal noise predictive filtering. Instead of predicting noise based only on past samples, the system uses future noise samples to predict and filter current noise, thereby effectively addressing burst errors that causal filtering cannot handle

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The system performs preliminary noise prediction using future noise samples before the actual data detection occurs. By pre-calculating the noise characteristics and applying the anti-causal filter in advance, the system prepares optimized filtering parameters that improve subsequent error correction capability

Inventive Principle:
Principle #10Preliminary action

2Reliability

If anti-causal noise predictive filtering is implemented, then burst errors are reduced and bit error rate improves, but computational complexity increases

Engineering Contradiction:
Improvebit error rateVSAvoidfiltering algorithm complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the noise predictive filtering into multiple independent components: a noise predictive filter bank with multiple filters tuned to different noise patterns, and a selective application mechanism that chooses which filter to apply. This segmentation reduces overall computational complexity by avoiding the need to apply all filters to all data

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system changes the temporal parameter of the filtering operation by using anti-causal filters that operate with future noise samples. This parameter change allows the system to achieve better error rates without proportionally increasing complexity, as the anti-causal structure enables more efficient noise prediction

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If multiple passes through data detector and decoder are performed, then data recovery accuracy improves, but processing time increases

Engineering Contradiction:
Improvedata recovery accuracyVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The anti-causal noise predictive filtering performs preliminary noise reduction before data detection and decoding. By pre-filtering the data with optimized anti-causal filters, the system improves signal quality in advance, reducing the number of iterative passes needed through the detector and decoder, thereby decreasing total processing time

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS9026572B2Systems and methods for anti-causal noise predictive filtering in a data channel
Publication Date: 2015.05.05 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD
  • US9026572B2 patent drawing
  • US9026572B2 patent drawing
  • US9026572B2 patent drawing

AI summary

Various embodiments of the present invention provide systems and methods for data processing. As an example, a data processing circuit is disclosed that includes a data detector circuit. The data detector circuit includes an anti-causal noise predictive filter circuit and a data detection circuit. In some cases, the anti-causal noise predictive filter circuit is operable to apply noise predictive filtering to a detector input to yield a filtered output, and the data detection circuit is operable to apply a data detection algorithm to the filtered output derived from the anti-causal noise predictive filter circuit.