Dual-Chirp Photonics-Based Radar for Distance and Velocity Measurement Based on Compressive Sensing

Abstract

We proposed a dual-chirp microwave photonic radar based on compressive sensing for distance and velocity measurement. This radar can generate different chirp linear frequency modulated (LFM) signals using a dual-parallel Mach-Zehnder modulator (DPMZM). In the receiving part, a dual-drive Mach-Zehnder modulator (DDMZM) and a Mach-Zehnder modulator (MZM) are cascaded for the optical mixing and de-chirp processing with a pseudo-random bit sequence (PRBS). Then the mixed signal can be gathered by an analog-to-digital converter (ADC) at a sampling rate that is well below the Nyquist sampling rate. Using fewer sampling points, the reconstruction algorithm can recover the de-chirped signal accurately with a compression ratio of 8. A proof-of-concept experiment demonstrates that when the target is stationary, the distance measurement error is about 1.560 cm. The signal-to-noise ratio (SNR) of the recovery signal is enhanced to 30.725 dB. When the target is moving, the simulation results present that the maximum distance error is 1.2 cm, and the velocity error is below 0.140 m/s. This compressive sensing radar reduces the pressure of a massive amount of data storage or processing and guarantees the accuracy of signal recovery. At the same time, it breaks the limitation of operation bandwidth and increases the speed of operation.

Keywords

• Compressive sensing
• microwave radar
• sub-Nyquist sampling
• optical mixing