Research on Acquisition Method for High-Dynamic and Weak Signals in SAR Satellites Based on Parameter Estimation

With the development of integrated space-air combat systems, SAR satellite constellations and space-based data link platforms collaboratively form an OODA (Observe, Orient, Decide, Act) autonomous closed-loop space-based information chain. Onboard receivers, as a critical component of this chain, are facing practical operational challenges such as high dynamics and low signal-to-noise ratio (SNR), particularly in the effective acquisition of signals with high Doppler frequency shifts. To address this issue, this paper investigates a time-domain parallel acquisition method based on Fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT), combined with parameter estimation for precise frequency compensation. A complete signal reception scheme is implemented on a platform consisting of an XC7K325T2FFG900I FPGA and an AD9361 transceiver. Theoretical analysis, simulation verification, and hardware testing demonstrate that the proposed algorithm not only significantly improves the acquisition speed and accuracy of high-dynamic signals in satellite receivers but also effectively enhances the detection capability for weak signals.