Fig. 1. Schematic diagram of the proposed sub-Nyquist radar receiver. LD, laser diode; ISO, optical isolator; PC, polarization controller; DD-MZM, dual-drive Mach–Zehnder modulator; PD, photodetector; PRBS, pseudo-random binary sequence; ADC, analog-to-digital converter; OMP, orthogonal matching pursuit; RX, receiving antenna.

Fig. 2. Reconstruction errors for (a) Doppler frequency and (b) delay.

Fig. 3. (a) Reconstruction errors of Doppler frequency for different signal periods; (b) average error of all data points for different signal periods.

Fig. 4. Reconstruction errors for (a) Doppler frequency and (b) delay, with a constant delay and Doppler frequency ranging from −70 to 70 kHz. The inset in (b) is the spectrum of the NLFM signal used.

Fig. 5. Reconstruction of two targets. The delay and Doppler frequency of the two targets are (a) 25 ns and 30 kHz, 100 ns and −50 kHz; (b) 25 ns and −50 kHz, 200 ns and 40 kHz.