Mobile Coherent Change Detection GPR
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Solution Overview
Problem
Conventional ground penetrating radar (GPR) systems are limited in detecting changes in underground regions due to clutter, temperature sensitivity, and the inability to maintain identical measurement paths during mobile operations, which hampers effective change detection processing.
Innovation Solution
A mobile coherent change detection GPR system with a linear array of antenna elements, a radar processor, and a registration module that generates a GPR difference image by spatially aligning images from different measurement passes, maintaining coherent operation and accounting for antenna array misalignment and temperature variations, using calibration and GPS/DGPS for precise location determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If change detection processing is applied to measurements widely separated in time, then temperature variation sensitivity degrades detection accuracy, but measurements taken closer in time reduce the ability to detect long-term changes
Solution Approach 1:
The system performs preliminary registration and alignment of antenna positions before change detection processing. By pre-correcting for positional variations and temperature-induced drifts through calibration data and GPS/DGPS tracking, the system prepares the measurement data in advance to compensate for temperature effects, enabling accurate change detection even when measurements are separated in time
Solution Approach 2:
The system uses feedback from GPS and DGPS position data to continuously track and correct antenna array positioning between measurement passes. This feedback mechanism allows the system to compensate for temperature-induced positional drifts and maintain measurement coherence over time, resolving the contradiction between time separation and detection accuracy
2Area of stationary object
If mobile GPR operation is used to survey large underground regions, then coverage area increases, but inability to maintain identical measurement paths prevents change detection processing
Solution Approach 1:
The system introduces GPS and DGPS positioning systems as intermediaries to track and record the precise location of the antenna array during mobile operation. This intermediary positioning data serves as a reference to mathematically reposition and align measurements from different passes, enabling change detection processing over large areas while maintaining measurement path consistency through computational correction
Solution Approach 2:
The system replaces the mechanical requirement of physically retracing identical measurement paths with a computational approach using GPS/DGPS data. Instead of mechanically constraining the mobile platform to follow the exact same trajectory, the system uses position data to virtually realign measurements, enabling flexible mobile operation over large regions while maintaining the precision needed for change detection
3Device complexity
If conventional GPR systems are used, then system simplicity is maintained, but clutter limits detection capability and prevents effective change detection
Solution Approach 1:
The system segments the change detection process into distinct computational stages: data acquisition with mobile GPR, GPS/DGPS position tracking, registration and alignment of measurements, and final change detection processing. This segmentation allows each function to be optimized independently while working together to overcome clutter limitations, enabling effective change detection without requiring complete system redesign
Solution Approach 2:
The system applies partial change detection processing by focusing on specific underground regions or feature types rather than attempting to detect all changes uniformly. By selectively applying change detection algorithms to areas of interest and using clutter suppression techniques targeted at specific interference patterns, the system achieves effective change detection capability while maintaining reasonable system complexity
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 accurate detection and localization of changes in underground regions, such as newly formed voids or shifts in soil layers, by generating a GPR difference image that highlights changes over time, improving detection capabilities beyond conventional systems.
Implementation Method 1
Each antenna element is configured to transmit a radar signal into an underground region and to receive a return radar signal from the underground region
Implementation Method 2
The electromagnetic field generated by each antenna element during transmission is substantially the same as the electromagnetic field generated by each of the other antenna elements during transmission
Implementation Method 3
The enclosure includes a material that attenuates radiation emitted from the antenna elements during transmission. The enclosure is configured to pass the radar signals from the antenna elements and to pass the return radar signals from the underground region
Data Source
AI summary
Described are a method and system for detecting and locating changes in an underground region. Changes are detected using a mobile coherent change detection ground penetrating radar (GPR). The GPR system is located on a mobile platform that makes two more measurement passes over the same route to acquire GPR images of an underground region at different times. A lateral offset between the GPR images for the two different times is determined and applied to one of the GPR images to generate a GPR shifted image that is spatially aligned with the other GPR image using a correlation process or other technique. A GPR difference image is generated from the GPR shifted image and the other GPR image. The GPR difference image includes data representative of changes to the underground region that occurred between the two measurement passes.