航空瞬变电磁合成孔径成像算法关键技术研究

A study of the key techniques for airborne transient electromagnetic synthetic aperture imaging algorithm

将等效导电平面快速算法与合成孔径相关叠加技术相结合,实现了航空瞬变电磁快速成像解释算法。为了进一步获得更好的成像效果与更优的分辨率,对合成孔径算法中的关键技术进行了研究。首先给出最佳孔径尺寸的求取方法,并通过多个模型进一步验证孔径尺寸对于成像效果的显著影响;接着利用大量数值模拟结果分析孔径大小与异常体埋深、围岩与异常体电阻率比值等因素之间的关系,总结规律利用数值拟合方法求取其函数表达式,并根据函数表达式直接确定最佳孔径尺寸的大小;最后,利用多个模型示例证实合成孔径成像方法能够有效圈定异常范围、提高横向与纵向的目标分辨率,并且该方法不受海量航空数据的影响,计算速度快、可用于实时成像。以上研究成果进一步提高了航空瞬变电磁法的解释精度,为丰富航空瞬变电磁解释方法、提高勘探效率提供了理论依据。

In order to ease the growing contradiction between mineral resources supply and demand and realize the effective exploration of the complex terrain region,it is urgently necessary to improve the computational efficiency and interpretation accuracy of the ATEM（ Airborne Transient Electromagnetic） system. In this paper,the authors used differential conductance and synthetic aperture algorithm to realize fast imaging for ATEM system. In order to further improve the resolution and interpretation accuracy,the authors made an in-depth study of the key technology of synthetic aperture algorithm. Firstly,the authors provided a method for calculating the optimum aperture,and further verified that the aperture size could significantly influence the imaging effect. Then,by using numerical simulation method,the authors calculated the function expression of optimum aperture based on a lot of model calculation results. Finally,by using a multiple model example,the authors confirmed that the synthetic aperture imaging method can effectively improve the resolution both in lateral and vertical directions. This method is not affected by the impact of the massive air data and also has the characteristics of fast computing speed and can be used for real-time imaging. It can further improve the interpretation precision of the airborne transient electromagnetic method. The research results enrich the ATEM interpretation method and provide an important theoretical basis for improving the prospecting precision.