Acoustic Transfer Function Intrusion Detection System
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Solution Overview
Problem
Existing security and monitoring systems face challenges such as high power consumption, need for illumination at night, inoperability due to IR cut-off devices, low efficiency of sound waves in air layers, and difficulty in detecting intrusions with obstacles, especially in wide spaces and quiet environments, leading to maloperations and noise pollution issues.
Innovation Solution
A low-power security and monitoring system based on variation measurement of sound transfer characteristics, using a sound source generating device to output sound waves within a predetermined frequency band and a sound measuring device to calculate and compare acoustic transfer functions before and after intrusion, allowing for reliable intrusion detection without illumination and reducing noise pollution by using pink noise, white noise, or sine waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ultrasonic waves are used for intrusion detection, then the detection principle is simple and easy to implement, but a dead zone is generated when the security space is extended to wide spaces and intrusion at the back of existing objects cannot be detected
Solution Approach 1:
The system divides the monitoring space into multiple zones with multiple sound sources and sound measuring devices positioned at different locations. Each device monitors a specific sector, and the combined coverage eliminates dead zones while maintaining the simplicity of acoustic detection principles.
Solution Approach 2:
The system transitions from single-point ultrasonic detection to multi-dimensional acoustic field monitoring by deploying multiple sound sources and sensors in three-dimensional space, enabling detection around obstacles and across wide areas through spatial distribution.
2Reliability
If environmental sound is used for monitoring, then the system can operate in quiet environments, but maloperation possibility increases when the surrounding environment is quiet at the time of initial setting and the system becomes very sensitive to surrounding noise after learning
Solution Approach 1:
The system performs preliminary characterization of the acoustic transfer function during an initial setting phase before normal monitoring begins. This pre-established baseline allows the system to distinguish between normal environmental variations and actual intrusions, reducing false alarms in quiet environments while maintaining sensitivity to genuine threats.
Solution Approach 2:
The system continuously compares real-time acoustic measurements against the pre-established transfer function model, using feedback mechanisms to adjust detection thresholds and distinguish between benign environmental noise and actual intrusion events, thereby reducing maloperations.
3Measurement precision
If sound pressure difference is used for intrusion judgment, then the system can detect intrusions, but noise pollution from outside while measuring causes difficulties in actual implementation
Solution Approach 1:
The system uses the acoustic transfer function as an intermediary model that characterizes the normal acoustic pathways and reflections in the monitoring space. By comparing actual measurements against this intermediary model, the system can filter out external noise pollution and identify only those sound variations that represent actual intrusions.
4Reliability
If 24-hour monitoring is implemented, then continuous security is provided, but power consumption is high
Solution Approach 1:
The system implements periodic acoustic measurements rather than continuous high-power operation. Sound sources emit test signals at intervals, and the microprocessor calculates acoustic transfer functions periodically, enabling 24-hour monitoring coverage while significantly reducing average power consumption compared to continuous active monitoring.
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 24-hour low-power operation with high reliability, accurate intrusion detection even behind obstacles, and reduced noise interference, improving monitoring efficiency and reducing maloperations due to surrounding noise.
Implementation Method 1
a sound source generating device outputting a sound wave of an audible frequency band having a predetermined frequency band within a predetermined monitoring space
Implementation Method 2
a sound measuring device calculating a acoustic transfer function which is a unique characteristic value of the monitoring space by receiving the sound wave outputted from the sound source generating device
Implementation Method 3
the sound measuring device judges intrusion or no intrusion by comparing a acoustic transfer function measured in a monitoring mode with a acoustic transfer function measured in an initial setting mode
Data Source
AI summary
Disclosed are a method for measuring a acoustic transfer function of a predetermined space to be secured or monitored through a correlation between sound signals acquired from a sound source generating device and a sound measuring device and a method and a system for judging whether there is an intrusion object by using a difference between an initially set acoustic transfer function information and varied acoustic transfer function information by using the method for measuring the transfer function. In the present disclosure, when an object moves or an intrusion object is generated in a predetermined space, intrusion or no intrusion is monitored by variation of the acoustic transfer function varied by the intrusion object even though there is no noise generated by the intrusion object.