Monocular Single-band Passive Ranging Based On Spectrum Absorption Characteristics Of Oxygen

In modern electronic countermeasures, with the increasing demand for accuracy and attack speed of military equipment, the requirement on the accuracy and applying range of passive ranging has become higher and higher. With the development of photovoltaic technology, related research on infrared target transmission through atmosphere increased even more deeply, the passive ranging method on the transmission characteristics of the atmosphere also has been given great attention. Because the distribution of oxygen in the atmosphere is constant, and the interference of other gases in the vicinity of A-band is very small, the result of passive ranging by using oxygen absorption characteristics is in higher accuracy and longer distance.With the theory of oxygen absorption spectral characteristics, this paper established the atmospheric infrared transmission models under different transmission conditions by using atmospheric simulation software MODTRAN, and obtained a series of transmission parameters. This paper determined the way to study the oxygen absorption rate, and did the research on the effects of different changing environmental conditions, for example zenith-angel, elevation, latitude and longitude of observation location, and so on, on oxygen absorption rate respectively. Then, this paper got the empirical formulas for the change in the oxygen absorbance with different environmental conditions.Based on the previous studies, the scope of the study on passive ranging by using oxygen absorption A-band is identified. With the research on the existing passive ranging project, this paper proposed that using several common S-type curves as the empirical formulas of average oxygen absorbance changing with the transmission distance for research. Considering the performance and the algorithmically complex of the formulas, combining with the actual needs, the empirical formula of average oxygen absorbance changing with the transmission distance is determined.In order to do the research on the relationship between oxygen absorbance and transmission distance comprehensively and meticulously, and ultimately achieving passive ranging, this paper proposed that in different transmission distances, building the three-dimensional model in which the oxygen absorbance changing with the zenith-angle and the elevation of the observation location. During the implementation process, this paper built the three-dimensional models of the radiation transmission distances of 5km,10km,20km,35km, and 50km through a large number of calculations and fittings. And eventually integrate these five models in one three-dimensional system. By using this model, the passive ranging simulation experiments were conducted and the accuracy of the ranging relative error is within 3%. It verified the feasibility of passive ranging by building the three-dimensional model, and also provides a new way for passive ranging based on oxygen absorption characteristics.