We present the first kernel-fused SAR Range Doppler pipeline on any GPU platform. By fusing FFT, matched-filter multiply, and IFFT into a single Metal compute dispatch -- keeping all intermediate data in 32\,KiB on-chip memory -- we process a 4096×4096 complex SAR scene in \textbf{370\,ms} on an Apple M1 GPU, a \textbf{22×} speedup over the multi-dispatch baseline (8.16\,s). We further report the first FFT to exploit Apple's \texttt{simdgroup\_matrix} 8×8 hardware MMA, enabled by an in-place Cooley--Tukey decimation-in-frequency formulation that halves the memory footprint versus Stockham. Radar image quality is preserved: all five point targets show 0.0\,dB SNR deviation from the unfused FP32 reference.
@article{arxiv.2604.03585,
title = {From 8 Seconds to 370ms: Kernel-Fused SAR Imaging on Apple Silicon via Single-Dispatch FFT Pipelines},
author = {Mohamed Amine Bergach},
journal= {arXiv preprint arXiv:2604.03585},
year = {2026}
}