Digital Signal Post-Processing Distortion Limitation
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Solution Overview
Problem
Existing signal processing techniques for reducing quantization noise in digital signals, such as those used in telecommunications, often compromise the natural quality of the signal, particularly in music signals, as they struggle to distinguish between quantization noise and environmental noise, leading to suboptimal intelligibility and quality.
Innovation Solution
A method is introduced that limits distortion during post-processing by assigning an intermediate amplitude to the output signal, ensuring it remains within a defined tolerance of the decoded signal's amplitude range, using a delay line for temporal correspondence and defining permitted amplitude intervals based on the decoded signal's values, thereby preserving the signal's natural aspect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If aggressive post-filtering is applied to eliminate quantization noise, then quantization noise is reduced, but the signal becomes less natural and muffled
Solution Approach 1:
The patent uses feedback by comparing the post-processed signal with the original decoded signal and using this comparison to adjust the output. The difference signal is processed through a gain control mechanism that prevents excessive filtering while maintaining noise reduction, thus preserving signal naturalness while reducing quantization noise
Solution Approach 2:
The patent applies partial action by using a gain control mechanism that only applies filtering when necessary. The gain factor is adjusted based on the comparison between processed and original signals, applying just enough filtering to reduce noise while avoiding over-filtering that would degrade signal quality
2Object-affected harmful factors
If conventional noise reduction processing is applied, then environmental noise is reduced, but atmospheric noise is also removed which degrades music signal quality
Solution Approach 1:
The patent applies local quality by treating different noise components differently. The feedback mechanism allows selective attenuation - quantization noise is reduced while atmospheric noise is preserved. The gain control operates locally on the difference signal to achieve targeted noise reduction without affecting desirable signal components
3Object-affected harmful factors
If quantization noise is reduced through post-processing, then signal quality is improved, but distortion is introduced that deforms the signal
Solution Approach 1:
The patent uses feedback to maintain signal fidelity while reducing noise. The output signal is continuously compared with the decoded signal, and this feedback controls the gain applied to the difference signal, ensuring that noise reduction does not exceed the point where signal distortion becomes problematic
Data Source
AI summary
The invention relates to the processing of a digital signal originating from a decoder and a noise reduction post-processing step, including, in particular, limitation of distortion introduced by the post-processing step in order to deliver a corrected output signal (SOUT), assigning said corrected output signal (SOUT) with: a current amplitude having an intermediary value between a current amplitude value of the post-processed signal (SPOST) and a corresponding current amplitude value of the decoded signal (S′MIC), or the current amplitude of the post-processed signal (SPOST), according to the respective values of the current amplitude of the post-processed signal (SPOST) and by the corresponding current amplitude of the decoded signal (S′MIC).