Subsurface Intrusion Detection via Depth-Resolved Vibration Analysis
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Solution Overview
Problem
Existing subsurface activity detection systems have a high false alarm rate due to acoustic, RF, and surface events, making it difficult to accurately distinguish between surface and subsurface activities.
Innovation Solution
Deploying groups of vibration sensors with both shallower and deeper sensors, and using signal processing to compare relative values of vibration features such as amplitude, duration, and frequency content to differentiate between surface and subsurface activities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If vibration sensors are deployed along the boundary to detect subsurface activity, then the ability to detect tunneling or underground activity is improved, but the false alarm rate increases due to acoustic, RF and surface events
Solution Approach 1:
The system segments the detection problem by using multiple sensors at different depths (shallower and deeper sensors) to separately capture surface and subsurface vibrations. This segmentation allows the system to analyze depth-specific vibration patterns and distinguish between surface events (which primarily affect shallower sensors) and subsurface events (which affect both sensors differently), thereby reducing false alarms while maintaining detection accuracy.
Solution Approach 2:
The system adds the depth dimension to the detection system by deploying sensors at multiple depths vertically. This dimensional addition allows the system to differentiate events based on their depth characteristics - surface events produce different depth profiles compared to subsurface events, enabling the system to filter out false alarms from surface activities while maintaining sensitivity to genuine subsurface threats.
2Device complexity
If single-depth vibration sensors are used to detect subsurface activity, then the system complexity is reduced, but the ability to distinguish between surface and subsurface activity deteriorates
Solution Approach 1:
The detection system is segmented into multiple depth levels with shallower and deeper sensors. This segmentation enables the system to capture distinct vibration signatures from different depths, providing the necessary data to differentiate between surface and subsurface activities through comparative analysis of the vibration patterns at each depth level.
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
This approach significantly reduces the false alarm rate by accurately identifying subsurface activity, allowing for effective detection of unauthorized tunneling or other subsurface attempts.
Implementation Method 1
vibration sensors are deployed along the boundary. The outputs of the vibration sensors are taken as an indication of underground activity
Data Source
AI summary
A system to detect subsurface activity. The system employs vibration sensor pairs, with each sensor pair having a shallow sensor and a deep sensor. Outputs of the sensors of a pair are processed together and events are detected based on the relative values detected by the sensors of the pair. When signal energy departs from a detected background level, the relative amplitude and frequency content of vibrations measured at the shallow and deep sensors may be compared. The comparison may be performed, at least in part, using a classifier that discriminates between subsurface activity and surface activity. The outputs of sensor pairs may be aggregated to make a determination of whether subsurface activity exists and/or its location. Aggregation may involve comparing the outputs of the same sensor pair at multiple time intervals or may involve comparing the outputs of arrayed sensor pairs.