基于级联MZM的压缩感知微波光子测距雷达（特邀）

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

摘要:

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2cm。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。

Abstract:

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 2cm. In addition, it reduces the pressure of data sampling, storage and information processing, and it breaks Nyquist sampling theory.