为了给制导系统半实物仿真器设计过程中像元映射比选取提供准确的依据，根据探测器与仿真器空间光调制器的工作原理，研究了像元映射比对半实物仿真实验的影响。将随机靶标特有的频谱分布特性引入到仿真实验模型中，进行频谱计算，分析了不同像元映射比、不同相位变化对调制传递函数的影响，获得了映射比与调制传递函数之间的变化曲线。分析结果表明：当映射比为0.31和0.71时，相位变化对调制传递函数的影响可以忽略不计，而且系统的调制传递函数下降最小，稳定性好。分析结果为像元映射比的选择提供了定量依据。

In the design process of hardware-in-the-loop scene simulator of a guidance system, in order to establish an accurate basis for the selecting of the pixel-mapping-ratio (PMR), the influence of PMR on the simulation has been analyzed based on the sampling properties of the detector of unit under test and the spatial light modulator of simulator. The unique characteristic of the spectral distribution of the random targets has been introduced into the simulation model to calculate the modulation transfer function. Furthermore, the modulation transfer function curves at different PMR and phases have been obtained. The results show that if the PMR is either 0.31 or 0.71, the influence of the phase variation on the modulation transfer function is negligible, and the modulation transfer function′s value shows minimum attenuation and good stability. The quantitative criterion can be provided in the design of scene simulators.