Phase Modulation One-Bit SAR Imaging

Low-bit quantization is an effective way to reduce the data volume and hardware burden of synthetic aperture radar (SAR) systems. However, conventional 1-bit quantization introduces strong nonlinear components, which may cause an increased background noise level and degrade the imaging quality. The single-frequency time-varying threshold (SFT) method can improve the imaging quality of 1-bit SAR, but it still relies on spectral separation to prevent harmful components from entering the imaging region. However, under low sampling rates, the limited spectral separation space may cause harmful components to be folded into the imaging spectral region. To solve this problem, this paper proposes a three-channel joint phase modulation method. In the proposed method, designed phase shifts are applied to both the echo signal and the threshold signal in three parallel channels. After quantization, phase compensation and combination are performed. In this way, the dominant harmful components are selectively suppressed, while the desired imaging component is preserved. Experimental results show that the proposed method achieves a cleaner spectral distribution and better SAR imaging quality under low sampling rates.