Passive Long Range Acoustic Sensor Using Sunlight Modulation
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Solution Overview
Problem
Existing remote acoustical sensing technologies, such as parabolic microphones and laser microphones, have limited range, are prone to noise interference, require significant power, and use non-covert artificial illumination, making them less effective for long-range and covert acoustic signal detection and analysis.
Innovation Solution
A Passive Long Range Acoustic Sensor utilizing naturally formed acousto-optical modulators to convert sounds into modulated light, establishing optical communications links for remote signal detection and analysis, with stereophonic and multi-channel capabilities, and incorporating advanced signal processing to suppress atmospheric noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If parabolic microphones are used for remote acoustic sensing, then acoustic signal detection is enabled, but the range is limited and noise interference is high
Solution Approach 1:
The patent replaces the mechanical parabolic microphone system with an acousto-optical system. Sound waves modulate the refractive index of a medium (acousto-optical effect), creating optical phase variations that can be detected over long distances. This substitution of mechanical acoustic focusing with optical modulation enables significantly extended range while maintaining signal detection capability.
Solution Approach 2:
The patent introduces light as an intermediary carrier to transmit acoustic information over long distances. Instead of directly detecting acoustic waves mechanically, the system uses optical waves as a mediator that can carry acoustic modulation information through the atmosphere, enabling long-range transmission without direct mechanical contact.
2Length of stationary object
If laser microphones are used for remote acoustic sensing, then sensing range is extended, but power consumption increases and artificial illumination is required
Solution Approach 1:
The patent employs ambient sunlight as a free, passive illumination source that automatically provides the necessary optical energy for the acousto-optical modulation process. The system does not require external power supply or artificial lighting, as the sun's own light serves the dual purpose of illumination and acoustic signal carrier, eliminating power consumption concerns.
Solution Approach 2:
The patent converts the typically problematic atmospheric turbulence and scattering that degrade optical communications into beneficial effects. By using the acousto-optical effect, these atmospheric variations actually enhance the modulation depth and signal visibility, transforming environmental noise into signal enhancement mechanisms.
3Length of stationary object
If laser microphones are used for remote acoustic sensing, then sensing range is extended, but covert operation is compromised due to artificial illumination
Solution Approach 1:
The system uses the sun's natural light as a passive, invisible illumination source that requires no active transmission. Since the modulation occurs on ambient light rather than requiring active laser transmission, the system operates completely passively and covertly, with no detectable artificial illumination signature.
4Reliability
If atmospheric optical turbulence is present in remote optical receiver links, then signal transmission is enabled, but noise interference increases
Solution Approach 1:
The patent converts atmospheric turbulence from a harmful noise source into a beneficial signal enhancement mechanism. The acousto-optical modulation creates optical phase variations that interact with atmospheric turbulence to produce detectable intensity modulations, transforming what would normally be degrading effects into useful signal components that improve detection capability.
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
Enables very long-range, covert, and sensitive acoustic sensing with improved signal detection and analysis, including beam forming, over distances of up to 40 kilometers, with low power consumption and compact, portable design.
Implementation Method 1
using variations and significant improvements of the theoretical basis of the photophone, invented by Alexander Graham Bell and Sumner Tainter during the early 1880's. The invention disclosed herein, and its several embodiments use naturally formed, acousto-optical modulators to convert nearby sounds into modulated light
Implementation Method 2
a remote optical receiver link (6) for local acoustical sources (5) and signals
Data Source
AI summary
This Passive Long Range Acoustical Sensor relates to means of sensing acoustical sources and signals, including multi-channel acoustical signals, such as various types of sounds, vibrations, flutter, turbulence, and the like, and at long distances through a natural optical channel, without the use of a laser or other artificial illuminating means. A modified multi-channel embodiment of the Passive Long Range Acoustical Sensor may use a combination of natural optical channels and active illumination means, such as laser or other artificial illuminating means, of producing additional optical channels.