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激光测距以其高空间分辨率、高灵敏度、全天候等优良特性在主动遥感领域倍受青睐。激光测距仪的灵敏度(最大测程)主要取决于激光发射能量、有效接收光学孔径和系统信噪比。在激光发射能量和有效接收光学孔径受到限制的情况下,如何降低系统噪声,将微弱的激光脉冲信号从噪声中提取出来,成为至关重要的问题。从激光测距的原理出发,分析了各种微弱信号的检测方法,得出相关法是一种简单实用的方法。通过自相关与互相关的对比,决定采用模拟自相关法来进行微弱激光脉冲信号的检测。给出模拟自相关法检测电路并对其进行了试验。试验结果表明,使用模拟自相关法的最小信噪改善比为4.5,灵敏度为未经过模拟自相关检测的3.16倍。
Laser ranging with its high spatial resolution, high sensitivity, all-weather and other excellent features in the field of active remote sensing much favored. Laser range finder sensitivity (maximum range) depends on the laser emission energy, effective optical aperture and the system to receive signal to noise ratio. How to reduce the system noise and extract the weak laser pulse signal from the noise are the crucial issues when the laser emission energy and the effective receiving optical aperture are limited. Starting from the principle of laser ranging, the detection methods of various weak signals are analyzed, and the correlation method is a simple and practical method. Through the comparison of autocorrelation and cross correlation, it is decided to adopt the analogue autocorrelation method to detect weak laser pulse signal. The circuit of analog auto-correlation detection is given and tested. The experimental results show that the minimum signal-to-noise ratio is 4.5 using the simulated autocorrelation method, and the sensitivity is 3.16 times that of the simulated autocorrelation.