Tone Generation Using Square Wave Harmonics

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Solution Overview

Problem

Existing electronic sound production systems for replicating mechanical tones, such as sirens and horns, are inefficient and require complex amplifiers that generate heat and consume significant power, while also being bulky due to the need for data storage and processing.

Innovation Solution

A tone generation system that uses a square wave signal generator to produce fundamental and harmonic frequencies, which are then amplified and played through a speaker, allowing for a simple digital amplifier and reducing the need for complex circuitry and heat sinks, using a combination of a moving coil speaker and piezoelectric drivers to enhance sound pressure levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If complex amplifiers are used to reproduce mechanical tones electronically, then sound quality can be maintained, but power consumption increases and heat generation occurs

Engineering Contradiction:

Improvetone reproduction fidelityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent replaces complex electronic amplifiers with a digitally controlled speaker system that directly generates the desired tone waveform. The microcontroller generates square wave signals at the fundamental frequency and harmonic frequencies, which are summed and fed directly to the speaker, eliminating the need for traditional amplifier circuits and thereby reducing power consumption and heat generation while maintaining tone fidelity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the approach from amplifying analog signals to directly generating digital waveforms with specific frequency parameters. By controlling the speaker with precisely calculated square wave signals at fundamental and harmonic frequencies, the system achieves accurate tone reproduction without the power-intensive amplification stage, thus resolving the contradiction between fidelity and power consumption.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If traditional electronic sound systems are used, then tone reproduction is achieved, but device size increases due to amplifier and heat sink requirements

Engineering Contradiction:

Improvesound production capabilityVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent eliminates the need for large amplifier circuits and heat sinks by replacing them with a compact digital signal generation system. The microcontroller generates the tone signals digitally, and these signals are fed directly to the speaker, removing the bulky power amplification hardware and thereby significantly reducing device volume while maintaining sound production capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If square wave signals with harmonics are generated, then efficient tone reproduction is achieved, but circuit complexity increases

Engineering Contradiction:

Improvetone generation efficiencyVSAvoidcircuit complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent uses a microcontroller to generate square wave signals with the desired fundamental and harmonic frequencies through software algorithms. This digital approach replaces complex analog circuitry with programmable logic, achieving efficient tone reproduction with harmonics while actually simplifying the overall circuit design, as the microcontroller can generate multiple frequency components without requiring additional analog signal generation circuits.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system achieves efficient and reliable tone reproduction with improved sound pressure levels, reduced size, and lower power consumption, while maintaining the fidelity of mechanical tones, with an efficiency of 97-98% and a compact design.

Implementation Method 1

a square wave signal generator configured to generate a first series of square wave signals to replicate a fundamental frequency of a desired mechanical tone, and a second series of square waves signals to replicate a second harmonic of the desired mechanical tone

Methodology Applied

Scientific EffectSquare wave generation:

Implementation Method 2

An amplifier is configured to receive the first and second series of square waves

Methodology Applied

Scientific EffectElectrical amplification:

Implementation Method 3

a speaker is connected to receive an output signal from the amplifier

Methodology Applied

Scientific EffectElectroacoustic conversion:

Data Source

PatentUS9900705B2Tone generation

Publication Date: 2018.02.20 FEDERAL SIGNAL CORPORATION

AI summary

A tone generation system includes a square wave signal generator configured to generate a first series of square wave signals to replicate a fundamental frequency of a desired mechanical tone, and a second series of square waves signals to replicate a second harmonic of the desired mechanical tone. An amplifier is configured to receive the first and second series of square waves, and a speaker is connected to receive an output signal from the amplifier.