天基平台下对飞机目标的探测具有距离远、目标信号能量弱的特点，需选择合理的谱段以得到较强的信号能量。本文通过建立系统对比度模型，从系统的角度分析对比度对探测谱段选择的影响，并结合目标和背景的辐射特性，对不同类型飞机在不同探测距离和探测角度下分析仿真，仿真结果表明：系统对比度可以有效选择探测的谱段，在不同波段处，系统对比度存在明显差异，且会随着探测距离和探测天顶角的增加而下降，但系统对比度的峰值不发生偏移，主要峰值点为4.15 μm 和4.4 μm，较强对比度波段为4.09～4.19 μm、4.3～4.5 μm、8～9.2 μm 和10.5～12 μm，上述波段比较适合用于飞机目标探测。

In the space-based platform, the long-distance detection of aircraft targets results in weak target-signal energy. Therefore, it needs to select a reasonable spectrum to get a strong target signal. In this paper, a system contrast model is built. The model analyzes the influence of contrast on the spectral section from a systematic point of view. According to the radiation characteristics of the target and background, the simulation of different types of aircraft under different detection distances and detection angles is analyzed. The simulation results show that the system contrast can effectively select the detection section, and the system contrast will decrease as the detection distance and detection zenith angle increase. There are obvious differences in contrast at different wavelengths due to the multiple influences of the target, background, and system. However, the contrast peak region does not offset; the main peak points are 4.15 μm and 4.4 μm, and the strong contrast bands are 4.09-4.19 μm, 4.3-4.5 μm, 8-9.2 μm, and 10.5-12 μm. They are suitable for aircraft detection.