Millimeter-Wave Imaging With Partitioned Inverse Reconstruction
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Solution Overview
Problem
Existing millimeter-wave and microwave imaging systems face challenges in achieving high resolution due to computational complexity and ill-posedness in inverse filtering, which is both memory-intensive and time-consuming, and often results in lower image quality.
Innovation Solution
The implementation of a partitioned inverse (PI) approach that partitions the measurement matrix for image reconstruction, utilizing pseudo inverse techniques with truncated singular value decomposition for regularization, allowing for parallel processing on GPUs or multicore CPUs, and using dynamic antenna systems with sub-wavelength elements to steer multiple orthogonal beams for enhanced resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If inverse filtering is used for image reconstruction, then image resolution is improved, but computational complexity and memory requirements increase significantly
Solution Approach 1:
The patent partitions the measurement matrix into multiple sub-matrices corresponding to different spatial regions or frequency bands. This segmentation allows the inversion operation to be performed on smaller sub-matrices independently, reducing the overall computational complexity from O(N³) for a full N×N matrix to a sum of smaller operations, while maintaining the resolution benefits of inverse filtering.
Solution Approach 2:
The patent applies truncated singular value decomposition (TSVD) as a preliminary regularization step before inversion. By pre-computing and truncating small singular values, the system prepares the measurement matrix to be better conditioned, reducing the computational burden and memory requirements of the subsequent inversion operation while improving numerical stability.
2Measurement precision
If inverse filtering is used for image reconstruction, then image resolution is improved, but processing time increases
Solution Approach 1:
The measurement matrix is divided into multiple independent or semi-independent blocks that can be inverted in parallel. This block partitioning enables concurrent processing on multi-core systems or GPU architectures, reducing the overall processing time from sequential inversion of the full matrix to parallel inversion of smaller blocks, while preserving the high resolution output.
Solution Approach 2:
The patent uses truncated singular value decomposition to retain only the most significant singular values and corresponding vectors, discarding less important components. This partial action approach computes only the essential parts of the inversion needed for high-quality image reconstruction, significantly reducing processing time while maintaining or even improving image quality by eliminating noise from truncated components.
3Measurement precision
If a large number of antenna elements are used to form a large aperture, then image resolution is improved, but device complexity and cost increase
Solution Approach 1:
The patent employs signal processing techniques in the frequency and spatial domains to synthesize a larger effective aperture from a smaller physical antenna array. By utilizing spectral analysis and coherent integration across multiple frequencies and spatial samples, the system achieves the resolution equivalent of a larger aperture without the corresponding increase in hardware complexity.
Solution Approach 2:
The patent changes operational parameters such as frequency, polarization, and temporal modulation to extract additional independent measurement dimensions from the same physical antenna elements. By varying these parameters and applying advanced signal processing, the system effectively increases the information content per antenna element, achieving higher resolution without adding more physical elements to the array.
Data Source
AI summary
Examples of imaging systems are described herein which may implement microwave or millimeter wave imaging systems. Examples described may implement partitioned inverse techniques which may construct and invert a measurement matrix to be used to provide multiple estimates of reflectivity values associated with a scene. The processing may be partitioned in accordance with a relative position of the antenna system and/or a particular beamwidth of an antenna. Examples described herein may perform an enhanced resolution mode of imaging which may steer beams at multiple angles for each measurement position.