Photonic RF Storage With Tunable Doppler Frequency Shift Based on Carrier-Suppressed Single-Sideband Signal

In this paper, a microwave photonic scheme capable of simultaneous high-fidelity radio frequency (RF) storage and tunable frequency shift is proposed for the radar repeater jamming. The distance and velocity joint deception is realized by controlling the time delay and Doppler frequency shift (DFS) of the echo signal. The RF signal is converted in optical domain in the form of carrier-suppressed single-sideband (CS-SSB) signal and stored in the active fiber loop with high fidelity. Meanwhile, DFS function is realized by adjusting the relative frequency shift between the CS-SSB signal in the upper path and the optical carrier in the lower path. The experimental results demonstrate the capability to store the linear frequency modulated (LFM) signal at the central frequency of 10 GHz with a bandwidth of 1 GHz for 2.018 ms (corresponding to 200 circulations) with the signal-to-noise ratio degradation of 3.4 dB. The time-frequency diagrams and matched filtering results confirm that the stored LFM signal maintains high frequency modulation linearity. In addition, a frequency tuning range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm$</tex-math></inline-formula>1 MHz is realized with the spurious suppression ratio of 40 dB.