Microwave Photonic Radar For Distance And Velocity Measurement Based On Optical Mixing And Compressive Sensing

We propose a microwave photonic compressive sensing radar for distance and velocity measurement. First, a dechirped signal that carries distance or velocity information is extracted between the transmitted and received signals in the proposed system. Then it is mixed with a pseudo-random bit sequence in the optical domain using a Mach-Zehnder modulator. After that, the de-chirped signal can be acquired by a photodetector and an analog-to-digital converter (ADC) at a sub-Nyquist sampling rate. Finally, a reconstruction algorithm can be used to recover the de-chirped signal. In our test, the bandwidth of ADC can be shortened from 2 GHz to 500 MHz, leading to a compression factor of four. A series of frequencies from 1.043 GHz to 1.875 GHz can be compressed with a 500-MHz ADC and recovered using a reconstruction algorithm. For a moving target, the Doppler frequency shift can be calculated, and the direction of the moving target can be distinguished. The maximum relative error of distance measurement is 0.21%. The maximum relative error of velocity measurement is 2.6%. The signal-to-noise ratio can be developed from similar to 15 dB to similar to 30 dB. This microwave photonic compressive sensing radar can achieve distance and velocity measurements using few samples. Also, it provides a large bandwidth of system operation and reduces data processing and storage pressure. (C) 2021 Optical Society of America