Organizations: Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY, 12180 USA · Department of Computer Science, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY, 12180 USA
With modern defense applications increasingly relying on inexpensive, autonomous drones, lies the major challenge of designing computationally and memory-efficient onboard algorithms to fulfill mission objectives. This challenge is particularly significant in Synthetic Aperture Radar (SAR), where large volumes of data must be collected and processed for downstream tasks. We propose an online reconstruction method, the Online Fast Iterative Shrinkage-Thresholding Algorithm (Online FISTA), which incrementally reconstructs a scene with limited data through sparse coding. Rather than requiring storage of all received signal data, the algorithm recursively updates storage matrices for each iteration, greatly reducing memory demands. Online SAR image reconstruction facilitates more complex downstream tasks, such as Automatic Target Recognition (ATR), in an online manner, resulting in a more versatile and integrated framework compared to existing post-collection reconstruction and ATR approaches.
Figures & tables
Fig. 1 : Example of non-vectorized edgelet based atoms.
FISTA
Online FISTA
Variables
c,H,{dk,Gk,Rk}k=1n
c,H,An,bn
Values Stored 1 1 1 We assume storing complex values takes twice as much memory as storing a real valued number, and therefore multiply by 2 .
(M)(N+1)+(2nNr)(1+M+Nr)
(M)(N+1)+(2M)(M+1)
TABLE I : Memory Table.
Fig. 2 : Experiment sample scenes.
Fig. 3 : Large coefficients ( c>2×10−2 ) compared to slow-time over each scene.
Fig. 4 : SNR Gain vs slow-time comparison between Online FISTA and BP. Gain is measured in the difference between the SNR of Online FISTA and BP at each slow-time instance.
Fig. 5 : Partial reconstruction comparison between Online FISTA and BP.
Technical University of Munich, Munich, Germany · Remote Sensing Technology Institute, German Aerospace Center (DLR), Weßling, Germany · Department of Aerospace Engineering, University of the Bundeswehr Munich, Neubiberg, Germany