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为实现基于微多普勒效应的远距离目标探测和识别,研究了采用声光移频器的激光外差相干探测结构对目标微多普勒特征探测的影响。建立了声光移频器驱动功率与系统信噪比之间的数学模型,并进行了仿真计算,搭建了1550 nm激光外差/零差相干探测实验平台对所建模型进行了验证。研究结果表明:在移频器驱动电压限定范围内,驱动电压越高,对微多普勒效应探测的效果越好,得到的目标特征越明显,与理论分析一致。通过对比实验发现在同样条件下,外差探测得到的反映目标特征的时频分布曲线较零差的清晰,特征提取误差小,可读性更高,说明外差探测结构更有利于复杂的远距离目标探测。
In order to realize long-range target detection and recognition based on micro-Doppler effect, the influence of laser heterodyne coherent detection structure using acoustic-optical frequency shifter on target micro-Doppler detection was studied. The mathematical model between the driving power of the acousto-optic frequency shifter and the signal-to-noise ratio of the system is established, and the simulation calculation is carried out. The 1550 nm laser heterodyne / homodyne detection experiment platform is established to verify the model. The results show that the higher the driving voltage is, the better the effect of micro-Doppler effect detection is. Within the limited range of the driving voltage of the frequency shifter, the more the target characteristics are obtained, which is consistent with the theoretical analysis. The comparison experiment shows that under the same conditions, the time-frequency distribution curve reflecting the target characteristics obtained by heterodyne detection is more clear than the zero difference, the feature extraction error is small and the readability is higher, indicating that the heterodyne detection structure is more conducive to the complex and far Target detection.