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面向远距离目标微多普勒效应的探测,建立了本振光功率变化对激光平衡外差探测回波信噪比影响的数学模型,并进行了仿真分析。通过搭建的1 550 nm激光平衡外差探测实验平台测试了由于本振功率变化对于目标微多普勒特征提取效果的影响。研究结果表明,对于平衡外差探测,由于两光电探测器量子效率不可能完全匹配,考虑到散粒噪声、热噪声和本振相对强度噪声的影响,将存在一个最佳本振功率值使探测信噪比达到最大。当选取该本振功率进行探测时,获得的目标微多普勒特征可读性更强,提取误差更小。
For the detection of long-range target micro-Doppler effect, a mathematical model of the influence of local optical power variation on the signal-to-noise ratio of laser balanced heterodyne detection echo was established and simulated. The effect of local power variation on the target micro-Doppler feature extraction was tested by the built-in 1 550 nm laser balance heterodyne detection platform. The results show that for the balanced heterodyne detection, the quantum efficiency of the two photodetectors can not be completely matched. Taking into account the effects of shot noise, thermal noise and local oscillator relative intensity noise, an optimal local oscillator power value will exist to enable the detection Signal to noise ratio to maximum. When the local oscillator power is selected for detection, the target micro-Doppler characteristics obtained are more readable and the error of extraction is smaller.