Multi-Point SAR Backprojection for Non-Planar Scene Imaging

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Solution Overview

Problem

Existing synthetic aperture radar (SAR) image generation techniques cause distortion, defocusing, and geo-registration errors when imaging highly non-planar scenes due to projections onto a tangential plane, neglecting topographic variations.

Innovation Solution

Generate a non-planar surface by interpolating slant ranges based on lock down points and radar pulse data, followed by back-projection to reduce phase errors and improve image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If radar phase history is projected to a tangential plane, then the SAR image generation process is simplified, but image distortion and defocusing occur for highly non-planar scenes

Engineering Contradiction:

Improveimage generation process complexityVSAvoidimage quality

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent applies curvature by representing the imaged surface as a non-planar surface (e.g., spherical or ellipsoidal) rather than a flat tangential plane. This allows the backprojection to account for the actual curved geometry of the Earth's surface, eliminating image distortion and defocusing while maintaining reasonable computational complexity through efficient backprojection algorithms.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Ease of operation

If a tangential plane projection is used, then processing is easier, but geo-registration errors are introduced

Engineering Contradiction:

Improveprocessing easeVSAvoidgeo-registration accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

By using a non-planar surface representation that matches the actual terrain geometry, the patent ensures that projected image coordinates accurately correspond to real-world geographic coordinates. This eliminates geo-registration errors while the backprojection method itself provides an efficient processing approach.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Manufacturing precision

If phase history is back-projected to a non-planar surface, then image quality improves, but computational complexity increases

Engineering Contradiction:

Improveimage qualityVSAvoidcomputational complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent changes the fundamental parameter of the projection surface from planar to non-planar, which improves image quality by accounting for terrain curvature. The computational complexity is managed through efficient implementation of the backprojection algorithm and potential use of pre-computed geometric parameters for the non-planar surface.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20260050082A1Multi-point backprojection synthetic aperture radar

Publication Date: 2026.02.19 RAYTHEON CO

AI summary

Systems, devices, methods, and computer-readable media improved synthetic aperture radar (SAR) images. A method includes identifying, based on sourced elevation data, N lock down points on a synthetic aperture radar (SAR) image, where N is an integer greater than one, determining, based on radar pulse data and the N lock down points, a slant range for each of the N lock down points resulting in N slant ranges, interpolating, based on the N slant ranges, slant ranges for pixels on an imaging grid of the SAR image resulting in interpolated slant ranges, and back-projecting, based on the interpolated slant ranges and the N slant ranges, the radar pulse data resulting in the SAR image.