Acoustic Fire and Intrusion Discrimination via Phase Analysis
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Solution Overview
Problem
Current security surveillance systems face challenges in accurately distinguishing between fire and intrusion situations using sound field variations, as they struggle to detect temperature distribution changes and differentiate between the two based on similar acoustic patterns.
Innovation Solution
A security surveillance system that employs a sound generating device to output multi-tone sound waves, a sound receiving device to capture sound field information, and a sound field signal processing device to analyze frequency shifts and temperature changes, allowing for the discrimination between fire and intrusion by comparing reference patterns with current sound field data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sound field variation based fire detecting scheme is used to detect fire in an early state, then fire detection capability is improved, but the ability to discriminate fire from intrusion is worsened due to difficulty in detecting temperature distribution change in detail and quantitatively
Solution Approach 1:
The patent transitions from analyzing only sound pressure magnitude to analyzing the complete sound field including phase information across multiple frequencies. By adding the dimension of phase analysis and frequency-domain decomposition, the system can detect subtle temperature distribution changes that cause characteristic sound field pattern shifts during fire events, while distinguishing them from intrusion patterns.
Solution Approach 2:
The patent changes the measurement parameters from simple sound pressure level to comprehensive sound field characteristics including phase, frequency spectrum, and spatial distribution. By monitoring how these parameters evolve over time and comparing them against reference patterns, the system achieves both early fire detection and reliable discrimination from intrusions.
2Measurement precision
If an intrusion detector detecting sound pressure variation is used to detect intrusion, then intrusion detection capability is improved, but the ability to detect temperature distribution change and discriminate from fire is worsened
Solution Approach 1:
The patent extends intrusion detection from simple sound pressure thresholding to multi-dimensional sound field analysis including phase information and frequency-domain characteristics. This enables the system to recognize the distinctive acoustic fingerprint of intrusions versus the thermal-driven sound field changes of fires.
Solution Approach 2:
The patent pre-establishes reference sound field patterns for both fire and intrusion scenarios under various conditions. By having these reference patterns ready for comparison, the system can rapidly and accurately discriminate between fire and intrusion events as they occur, rather than attempting to differentiate them in real-time without prior knowledge.
3Adaptability or versatility
If a combined fire detector detecting smoke, flame, and fire is used, then fire detection comprehensiveness is improved, but detection capability in early fire state with low temperature or smoke density is worsened
Solution Approach 1:
The patent replaces traditional fire detection mechanisms (smoke sensing, flame detection) with an acoustic field-based detection system. By listening to the subtle changes in sound field caused by thermal expansion and convection currents in the very early stages of fire, the system detects fires before smoke or visible flames are present, achieving superior early detection while maintaining comprehensive fire scenario coverage.
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 effectively discriminates between fire and intrusion situations by analyzing frequency shifts and temperature changes, reducing false alarms and improving the accuracy of security surveillance, especially in early fire detection and blind spot scenarios.
Implementation Method 1
a sound generating device outputting, into a set security surveillance space, a multi-tone sound wave formed of a linear sum of sine waves having a plurality of frequency components
Implementation Method 2
a sound receiving device obtaining sound field information for each frequency represented as sound pressure and a phase from a sound wave received in the security surveillance space
Implementation Method 3
the sound field variation is caused by a fact that changes in air density and sound wave speed according to a temperature change of surrounding air due to the fire affect sound wave transfer
Data Source
AI summary
Provided is a security surveillance system and method capable of separately detecting fire and intrusion situations on the basis of a sound field variation, including a sound generating device outputting, into a set security surveillance space, a multi-tone sound wave formed of a linear sum of sine waves having a plurality of frequency components, a sound receiving device obtaining sound field information for each frequency represented as sound pressure and a phase from a sound wave received in the security surveillance space, and a sound field signal processing device storing sound field information for each frequency obtained from the sound receiving device in a preparation mode, comparing the stored sound field information with current sound field information for each frequency output from the sound receiving device in a surveillance mode, and determining occurrence of a security situation.