Acoustic Guard for Microphone Directivity in GPS Receivers

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The directivity of unidirectional microphones in GPS receivers and rearview mirrors is compromised due to sound waves reflected from the windshield, which are received through the second acoustic opening, leading to environmental noise interference.

Innovation Solution

An acoustic guard is integrated to cover the second acoustic opening, featuring sound inlets at both ends to direct sound waves into the microphone module, maintaining the microphone's directivity by blocking reflected sound waves.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the second acoustic opening is exposed to receive sound waves, then the microphone can receive sound from multiple directions, but the directivity is deteriorated due to reflected sound waves from the windshield

Engineering Contradiction:

Improvesound reception capabilityVSAvoiddirectivity

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

An acoustic guard structure is introduced as an intermediary component between the reflected sound waves and the second acoustic opening. The guard includes sound inlets that allow direct sound waves to enter while blocking reflected sound waves from the windshield, thereby mediating the sound reception process to preserve directivity while maintaining versatility

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The acoustic guard is divided into multiple sound inlets (first sound inlet and second sound inlet) that are spatially segmented to receive sound waves from different directions. This segmentation allows the system to selectively accept sound from desired directions while rejecting reflected sound, resolving the contradiction between versatility and directivity

Inventive Principle:

Principle #1Segmentation

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 acoustic guard effectively protects the microphone from reflected sound waves, preserving its directivity and reducing environmental noise interference, ensuring clear sound reception from the driver or passengers.

Implementation Method 1

sound waves reflected by the windshield behind the GPS receiver

Methodology Applied

Scientific EffectSound wave reflection: Reflection

Implementation Method 2

The acoustic guard covers the second acoustic opening and comprises a first sound inlet allowing the sound waves to enter the acoustic guard and reach the second acoustic opening

Methodology Applied

Scientific EffectAcoustic absorption: Acoustic Absorption

Data Source

PatentUS7986800B2Device with acoustic guard

Publication Date: 2011.07.26 FORTEMEDIA INC

AI summary

A device includes a main body, a microphone module, and an acoustic guard. The microphone module is connected to the main body and comprises a first acoustic opening and a second acoustic opening, wherein the microphone module receives sound waves via both the first and second acoustic openings. The acoustic guard covers the second acoustic opening and comprises a first sound inlet via which the sound waves enter the acoustic guard and reach the second acoustic opening.