Photonics-assisted compressed sensing radar receiver for frequency domain non-sparse signal sampling based on dictionary learning.

A photonics-assisted radar receiver based on compressed sensing (CS) technology is proposed to receive frequency domain non-sparse radar signals. The radar echo signal is mixed with a pseudo-random binary sequence (PRBS) in a photonic random demodulator (RD) consisting of a laser diode (LD), a dual-drive Mach-Zehnder modulator (DD-MZM), and a photodetector (PD). After the mixed signal from the photonic RD is undersampled by an analog-to-digital converter (ADC), the echo signal is reconstructed in the digital domain using an overcomplete dictionary generated by the dictionary learning algorithm and sparse reconstruction algorithm. The target range can be then obtained by correlating the reconstructed echo signal and the transmitted one. Experimental results show that the proposed system can successfully reconstruct different kinds of undersampled non-sparse radar echo signals. When the compression ratio is 20, the ranging errors do not exceed 5 cm. The system provides a promising solution for recovering undersampled frequency domain non-sparse radar signals through photonics-assisted CS.