Subsonic Projectile Detection via Acoustic Wake Signature Analysis
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Solution Overview
Problem
Current techniques are inadequate for detecting the trajectory of subsonic projectiles due to the difficulty in distinguishing muzzle blast from background noise, as they rely on shockwave processing which is not applicable for subsonic speeds.
Innovation Solution
A gunshot sensor system utilizing an acoustic sensor and signal processor to differentiate between the wake signature and muzzle blast of a projectile, providing bearing and distance estimates by processing acoustic frequency information over time, effectively distinguishing between bullet sounds and background noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shockwave processing is used for projectile detection, then detection reliability is improved for supersonic projectiles, but the method becomes inapplicable for subsonic projectiles
Solution Approach 1:
The patent transitions from detecting shockwaves (supersonic parameter) to detecting wake signatures and muzzle blasts (subsonic parameters). This involves changing the detection parameter from high-speed shockwave acoustic features to lower-speed wake and muzzle blast acoustic features, enabling the system to detect both supersonic and subsonic projectiles
Solution Approach 2:
The patent develops a detection system that can handle both supersonic and subsonic projectiles using acoustic sensors. By incorporating multiple detection modes (shockwave detection for supersonic, wake signature and muzzle blast detection for subsonic), the system achieves universal applicability across different projectile speed regimes
2Reliability
If muzzle blast detection is used for subsonic projectiles, then detection capability is provided, but false alarms increase due to indistinguishability from background noise
Solution Approach 1:
The patent segments the acoustic detection into multiple distinct components: wake signature detection and muzzle blast detection. By separating these detection functions and analyzing their respective acoustic characteristics independently, the system can better distinguish genuine projectile events from background noise, reducing false alarms
Solution Approach 2:
The patent employs dynamic analysis of acoustic signals over time, examining the temporal evolution of wake signatures and muzzle blasts. By analyzing the dynamic characteristics and time-dependent behavior of these acoustic features, the system can differentiate them from static or differently-behaving background noise sources
3Measurement precision
If wake signature and muzzle blast processing is used for subsonic projectiles, then trajectory estimation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical or electronic sensor arrays with acoustic sensors that detect wake signatures and muzzle blasts. This substitution uses acoustic wave propagation physics to achieve trajectory estimation without requiring complex mechanical positioning systems or multiple synchronized sensors, thereby reducing device complexity while maintaining measurement precision
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 reliable detection and estimation of subsonic projectile trajectories without relying on shockwave processing, reducing false alarms and improving accuracy in identifying the source direction of the projectile.
Implementation Method 1
an acoustic sensor, operable to convert received acoustic oscillations into electrical signals
Implementation Method 2
an acoustic sensor, operable to convert received acoustic oscillations into electrical signals, and a signal processor operable to process such electrical signals
Data Source
AI summary
Trajectory estimate for a sub-sonic projectile can be derived from sampling a wake contribution of an acoustic signal detected at a multi-detector array. The wake contribution is sampled, in time, and the samples are processed to determine a bearing estimate for the projectile from which the acoustic wake derives.