Fig. 1. Schematic of the photonic ADC. OFC, optical frequency comb; SG, signal generator; D, dispersion; EDFA, erbium-doped fiber amplifier; MZM, Mach–Zehnder modulator; PD, photodetector; LPF, low pass filter; LNA, low noise amplifier; RTO, real-time oscilloscope.

Fig. 2. Results before and after photonic ADC sampling. (a) Spectrum. (b) Short-time Fourier transform (STFT) analysis. (c) Results after pulse compression.

Fig. 3. Spectrum of down-converting a signal from 4.08 GHz to 80 MHz. The measured noise figure is 11.4 dB.

Fig. 4. Schematic of the experimental setup of the broadband microwave photonic ISAR system. AWG, arbitrary waveform generator; LNA, low noise amplifier.

Fig. 5. Results after pulse compression. (a) Pulse compression result of the echoed wave from two static targets. (b) Range-Doppler map of four rotating small balls.