Airborne synthetic aperture radar (SAR) serves as critical battlefield reconnaissance equipment, yet it remains vulnerable to electromagnetic interference (EMI) in combat environments, leading to image-quality degrada...
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Airborne synthetic aperture radar (SAR) serves as critical battlefield reconnaissance equipment, yet it remains vulnerable to electromagnetic interference (EMI) in combat environments, leading to image-quality degradation. To address this challenge, this study proposes an EMI-effect prediction framework for airborne SAR electromagnetic environments, based on the Newton-Raphson-based optimization (nrbo) and XGBoost algorithms. The methodology enables interference-level prediction through electromagnetic signal parameters obtained from reconnaissance operations, providing operational foundations with which SAR systems can mitigate the impacts of EMI. A laboratory-based airborne SAR EMI test system was developed to establish mapping relationships between EMI signal parameters and SAR imaging performance degradation. This experimental platform facilitated EMI-effect investigations across diverse interference scenarios. An evaluation methodology for SAR image degradation caused by EMI was formulated, revealing the characteristic influence patterns of different interference signals in the context of SAR imagery. The nrbo-XGBoost framework was established through algorithmic integration of Newton-Raphson search principles with trap avoidance mechanisms from the Newton-Raphson optimization algorithm, optimizing the XGBoost hyperparameters. Utilizing the developed test system, comprehensive EMI datasets were constructed under varied interference conditions. Comparative experiments demonstrated the nrbo-XGBoost model's superior accuracy and generalization performance relative to conventional prediction approaches.
The inversion of oblique ionograms allows for extraction of ionospheric state information and retrieval of electron density profiles at midpoints along oblique sounding paths,However, traditional inversion methods oft...
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ISBN:
(纸本)9798350353129;9798350353136
The inversion of oblique ionograms allows for extraction of ionospheric state information and retrieval of electron density profiles at midpoints along oblique sounding paths,However, traditional inversion methods often face the problems of large computation and slow convergence. This paper presents an enhanced Newton-Raphson-based optimizer (nrbo) algorithm with dynamically adjusted decision factors (DF). It compares the inversion results with those obtained from various optimization algorithms. Experimental results demonstrate that the new algorithm outperforms the improved Particle Swarm Optimization (PSO) algorithm in both inversion accuracy and computational speed. In a multi-layer Quasi-Parabolic Segment (QPS) ionospheric model inversion scenario, even with an observation error increase of 10 km, the inverted electron density profiles closely approximate the true values, showcasing robust noise resistance. Thus, this method proves suitable for practical oblique ionogram inversion based on actual measurements.
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