Digital Audio Waveform Correction for Single Sine Wave Protection

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Solution Overview

Problem

Existing digital audio processing devices degrade sound quality when processing periodic signals of single sine waves, as they often add unwanted overtones, which compromises the quality of digital audio signals.

Innovation Solution

A digital audio processing device that includes a local extremum calculator, difference value calculator, correction value calculator, and periodic signal detector to identify and correct digital audio signals by adding and subtracting correction values based on sample intervals, with coefficients adjusted according to the signal's periodicity, thereby improving sound quality without degrading single sine wave signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If waveform correction processing is applied to digital audio signals, then sound quality of complex signals is improved, but sound quality of single sine wave signals is degraded due to addition of unwanted overtones

Engineering Contradiction:
Improvesound qualityVSAvoidunwanted overtones
Core Design Contradiction:
Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The periodic signal detector performs preliminary detection of the input signal characteristics before waveform correction processing is applied. By identifying whether the signal is periodic in advance, the system can conditionally apply or bypass the correction processing, preventing the generation of unwanted overtones in periodic signals while still improving complex signals.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts its processing behavior based on the detected signal characteristics. The waveform correction processing is enabled or disabled according to the periodicity detection result, making the system adaptive to different signal types and avoiding fixed processing that would harm periodic signals.

Inventive Principle:
Principle #15Dynamics

2Manufacturing precision

If correction values are added and subtracted based on sample intervals, then audio fidelity is enhanced, but periodic signals are distorted

Engineering Contradiction:
Improveaudio fidelityVSAvoidsignal periodicity
Core Design Contradiction:
Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The system performs preliminary detection of signal periodicity before applying correction values. This allows the system to preserve the stable periodic composition of periodic signals by bypassing correction processing, while still enhancing the fidelity of non-periodic signals through conditional application of correction values.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system applies different processing qualities to different signal types. Periodic signals receive no correction processing to maintain their stable composition, while non-periodic signals receive full correction processing to enhance fidelity. This localized quality approach ensures each signal type is treated appropriately.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3709299B1Digital audio processing device, method for processing digital audio, and digital audio processing program
Publication Date: 2021.12.08 JVC KENWOOD CORP
  • EP3709299B1 patent drawingFigure 1
  • EP3709299B1 patent drawingFigure 2
  • EP3709299B1 patent drawingFigure 3

AI summary

A local extremum calculator (11) detects a local maximum sample and a local minimum sample of a digital audio signal. A number-of-sample detector (12) detects a sample interval between the local maximum sample and the local minimum sample. A difference value calculator (13) calculates difference values between adjacent samples. A correction value calculator (14) calculates a first correction value by multiplying the difference value between the local maximum sample and a first adjacent sample by a coefficient and calculates a second correction value by multiplying the difference value between the local minimum sample and a second adjacent sample by the coefficient. An adder/subtractor (15) adds the first correction value to the first adjacent sample and subtracts the second correction value from the second adjacent sample. When a periodic signal detector (16) detects that the digital audio signal is a single sine wave, the digital audio processing device is configured not to add the first correction value to the first adjacent sample and subtract the second correction value from the second adjacent sample.