Wideband SAR Imaging via Nonuniform Sampling
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Solution Overview
Problem
Conventional microwave and millimeter wave wide-band three-dimensional (3-D) synthetic aperture radar (SAR) imaging techniques require a long time to scan and obtain images, making real-time imaging of large structures impossible due to the need for a large quantity of measurements.
Innovation Solution
A method involving nonuniform sampling of wide-band reflection measurement data and a fast 3D wide-band SAR algorithm to generate 3D SAR images in real-time, allowing for intelligent termination of data acquisition and post-processing for high-quality image optimization with reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional raster scanning is used to obtain sufficient measurement data for high-quality SAR images, then image quality and resolution are improved, but acquisition time increases to tens of minutes or several hours
Solution Approach 1:
The patent applies partial action by acquiring only a fraction of the measurement data traditionally required for SAR imaging. By using nonuniform sampling at reduced data density (e.g., 10-20% of conventional sampling rates), the system obtains sufficient information for acceptable quality images without completing full raster scans, thereby dramatically reducing acquisition time while maintaining functional imaging capability
Solution Approach 2:
The patent changes the sampling parameter from uniform grid spacing to nonuniform sampling patterns. This parameter change allows the system to capture essential scattering information with fewer measurements by strategically selecting probe positions based on real-time image quality assessment and sparsity constraints, resolving the trade-off between data quantity and acquisition time
2Loss of time
If nonuniform sampling with reduced data quantity is used, then acquisition time is reduced, but image quality and resolution may deteriorate
Solution Approach 1:
The patent implements feedback by continuously monitoring image quality metrics during the nonuniform sampling process. The system assesses whether the currently acquired data fraction produces acceptable image quality and uses this feedback to determine when to terminate scanning, ensuring that sufficient information has been captured while avoiding unnecessary additional measurements that would extend acquisition time
Solution Approach 2:
The patent applies preliminary action by pre-defining sparsity constraints and sampling patterns before data acquisition begins. These predetermined parameters guide the nonuniform sampling process to prioritize regions and orientations most critical for image formation, ensuring that the reduced data set captures the essential features needed for acceptable quality images
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 the rapid generation of SAR images with acceptable resolution using a fraction of the required data, facilitating real-time imaging of large structures with reduced acquisition time and improved image quality.
Implementation Method 1
a probe that has an aperture through which a signal, such as an electromagnetic signal, is transmitted incident to an object located in a medium of interest remotely from the probe
Implementation Method 2
instructions for obtaining a three-dimensional SAR image from the transformed spectral estimation data using Fourier transforms
Data Source
AI summary
Wideband synthetic aperture radar (SAR) imaging. A probe transmits a signal through its aperture incident to an object located in a medium of interest remotely from the probe. The probe receives through the aperture a plurality of nonuniformly sampled reflected signals from the object as the probe moves in a measurement plane located a predetermined distance from the object. A processor executes a SAR-based reconstruction algorithm to generate an image.