基于级联MZM的压缩感知微波光子测距雷达

Compressive Sensing Microwave Photonic Radar for Distance Measurement Based on Cascaded Mach-Zehnder Modulators

提出了一种基于级联马赫-曾德尔调制器(MZM)的微波光子压缩感知雷达测距系统。在发射端,利用双平行马赫-曾德尔调制器(DPMZM)产生中心频率和带宽四倍频的线性调频(LFM)信号;在接收端,对回波信号进行去斜处理,并利用级联的MZM实现去斜信号和伪随机序列(PRBS)在光域上的混频。通过低通滤波器(LPF)后,利用低速模数转换器(ADC)采用较低的速率对该混频信号进行亚奈奎斯特采样,然后在后端利用正交匹配追踪(OMP)算法对去斜信号进行重构。仿真和验证性实验结果表明,在数据压缩比为8时,该系统可以利用较少的观测值精确恢复去斜信号的频率值,测距误差不超过2 cm。除此以外,该系统降低了雷达中数据采集、存储和信息处理的压力,突破了传统奈奎斯特采样理论的瓶颈。

A microwave photonic compressive sensing radar is proposed for distance measurement based on cascaded Mach-Zehnder modulators(MZMs). In the transmitter, a dual-parallel Mach-Zehnder modulator(DPMZM) is used to generate the quadrupled linearly frequency-modulated(LFM) signals. In the receiver, the echo signal can be de-chirped and the de-chirped signal can be mixed with a pseudo-random bit sequence(PRBS) in the optical field by using cascaded MZMs. Then the mixed signal can be acquired by a low pass filter(LPF) and sampled at a sub-Nyquist sampling rate by using a low-speed analog-to-digital converter(ADC). Finally, orthogonal matching pursuit(OMP) algorithm can be used to recover the de-chirped signal. The results of the simulation and proof-of-concept experiment demonstrate that when the data compression ratio is 8, the system can reconstruct the frequency of the de-chirp signal with less observed value and the distance measurement error is less than 2 cm. In addition, it reduces the pressure of data sampling, storage and information processing, and it breaks Nyquist sampling theory.