Band Expander Using Differentiator Overtone Generation

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Solution Overview

Problem

Existing band expansion technologies, which use Fourier transform to improve sound quality, increase computational volume and power consumption, particularly in battery-driven devices, necessitating a method to minimize computation while maintaining sound quality and correlation with the original signal.

Innovation Solution

A band expander comprising a differentiator, overtone computation unit, high-pass filter, and combiner that generates and filters overtone signals to expand the frequency band without using Fourier transform, thereby reducing computational load and avoiding the superimposition of odd-order harmonics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If Fourier transform and inverse Fourier transform are used to expand frequency band, then natural sound reproduction is achieved, but computational volume and power consumption increase

Engineering Contradiction:

Improvesound qualityVSAvoidpower consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent extracts only the essential function of frequency band expansion from the Fourier transform process, implementing it through a simplified differentiator-based overtone generation system that achieves the same effect with minimal computation

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the computationally expensive Fourier transform with a simple differentiator circuit that can be implemented with basic mathematical operations, effectively using a 'cheap' computational approach to achieve the desired frequency expansion

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Manufacturing precision

If Fourier transform is used to expand frequency band, then sound quality is improved, but device complexity increases

Engineering Contradiction:

Improvesound qualityVSAvoidcomputational complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent substitutes the complex computational system (Fourier transform) with a simpler mathematical operation system (differentiation and multiplication), replacing a heavy computational mechanism with a lightweight algebraic approach

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If conventional band expansion methods are used, then frequency band is expanded, but odd-order harmonics are superimposed degrading sound quality

Engineering Contradiction:

Improvefrequency band expansionVSAvoidsound quality

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent converts the potential harm of harmonic superimposition into a benefit by using the differentiator to generate only even-order harmonics, which are musically pleasant, while eliminating the generation of odd-order harmonics that would degrade sound quality

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS10068580B2Band expander, reception device, band expanding method for expanding signal band

Publication Date: 2018.09.04 JVC KENWOOD CORP

AI summary

An oversampling LPF unit receives a sound signal. A differentiator differentiates the sound signal. An overtone computation unit generates an overtone signal by multiplying a signal differentiated by the differentiator by the sound signal from the oversampling LPF unit. A HPF unit filters the overtone signal generated by the overtone computation unit. A combiner combines the overtone signal filtered by the HPF unit and the sound signal from the oversampling LPF unit.