基于测距光谱通道数量和位置选定规则,以氧气A吸收带为例,从系统探测距离、目标与背景信噪比、系统工作海拔等约束条件对带宽的限制出发,利用MODTRAN和MATLAB软件综合仿真分析了满足系统实时性、目标信噪比及不同探测距离条件下通道带宽上下限的取值范围。结果表明:相同条件下,系统平台海拔越高,带宽下限取值越小、范围越大、选取越灵活,系统探测距离越远,有效探测范围也越大;目标信噪比要求越高,带宽下限取值越大、范围越小、选取越受限,探测距离和有效探测范围越小。因此,设计系统时应根据任务要求,确定光谱通道位置和数量,计算系统工作实时性、目标信噪比、系统最大最小工作距离等多重约束条件下各通道带宽取值上下限曲线,通过确定能够同时满足最大及最小工作距离条件的上下限曲线最小交集,便可在曲线交集区域内选定满足设计要求的通道带宽取值。这为单目多光谱被动测距系统的参数设计和工程化提供有效的理论支撑和计算方法,从而设计出高低精度搭配、远近距离兼顾的多光谱被动测距系统。

Taking the oxygen absorption band A as an example, we consider some constraints of the system such as detection distance, target and background signal-to-noise ratio(SNR), system operating altitude on the channel bandwidth based on the selection rules of number and position of ranging spectrum channels, and simulate and analyze the range of the channel bandwidth upper and lower limits to meet the real-time performance of system, target SNR and different detection distance conditions by using MODTRAN and MATLAB softwares. The results show that the higher the platform altitude is, the lower the lower limit of bandwidth is, the larger the range is, the more flexible the selection is, the longer the system detection distance is and the larger the effective detection range is under the same conditions; the higher target SNR requirement is, the larger the lower limit of bandwidth is, the smaller the detection range is, the less flexible the selection is, the smaller the effective detection range and scope are under the same conditions. Therefore, in the design of passive ranging system, we should firstly determine the location and number of spectrum channels based on the task design requirements, and then calculate the upper and lower limits curves of each channel under multiple constraints of the real-time system, the signal to noise ratio, and the maximum and minimum working distance of the system. Secondly it will be determined that the minimum intersection based on the upper and lower limit curves that satisfy both the minimum and maximum working distance. Finally, the best channel bandwidth values that meet the design requirements could be selected in the intersection. It can provide an effective theory support and calculation method for the parameter design and engineering of single-lens multi-spectrum passive ranging system with arbitrary precision and arbitrary distance.