Signal Processing Device for High Linear Density Optical Discs

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Solution Overview

Problem

In high linear density recording, existing technologies face challenges in improving noise resistance, which affects the decoding performance of signals.

Innovation Solution

A signal processing device and method that performs partial response (PR) equalization of multilevel codes and maximum likelihood decoding to enhance noise resistance, specifically designed for optical disc recording and reproducing systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional signal processing is used in high linear density recording, then recording capacity is increased, but noise resistance deteriorates

Engineering Contradiction:

Improverecording capacityVSAvoidnoise resistance

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The signal processing is divided into multiple specialized stages: PR equalization to handle inter-symbol interference, noise prediction to model and subtract noise components, and Viterbi decoding to perform maximum likelihood sequence estimation. This segmentation allows each stage to address specific noise sources and signal degradation mechanisms independently, maintaining noise resistance while supporting high linear density recording

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Noise prediction is performed before the main decoding process to pre-whiten the received signal. By predicting and removing noise components in advance, the subsequent Viterbi decoder receives a cleaner signal with improved signal-to-noise ratio, enabling reliable decoding at high linear densities where noise would otherwise be prohibitive

Inventive Principle:

Principle #10Preliminary action

2Quantity of substance

If linear density is increased, then recording capacity is improved, but signal quality deteriorates

Engineering Contradiction:

Improverecording capacityVSAvoidsignal quality

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The system employs iterative refinement where the decoded signal is fed back through the PR equalization and noise prediction stages. This feedback mechanism allows the system to continuously adjust and refine the signal estimation, compensating for the signal degradation that occurs at high linear densities and maintaining measurement precision

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The PR equalization parameters and noise prediction filters are optimized for high linear density conditions. By adjusting these parameters to match the specific characteristics of high-density recordings, the system maintains signal quality despite the increased density causing greater inter-symbol interference and noise

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11749307B2Signal processing device, signal processing method, and program

Publication Date: 2023.09.05 SONY GROUP CORP

AI summary

There is provided a signal processing device, a signal processing method, and a program capable of improving noise resistance in high linear density recording. Partial response (PR) equalization of a reproduced signal of multilevel codes of 3<=ML is performed and maximum likelihood decoding of an equalized signal obtained through the PR equalization is performed. The present technology can be applied to, for example, a recording/reproducing device or the like such as an optical disc.