通常西藏壁画地仗层的厚度不足10cm,有效去除直耦杂波是利用高频探地雷达识别壁画空鼓病害的关键,在此基础上计算空鼓的厚度.模拟制作西藏壁画地仗,在其内部预设深度和厚度各不相同的规则空鼓,通过正演模拟试验确定探地雷达的采集参数,积累数据处理的经验,并比较不同雷达天线的性能.结果表明,针对RAMAC探地雷达和Ground Vision数据采集、后处理软件,时窗深度宜为3ns左右,采样频率应不低于142GHz,效果最明显的两个滤波器是带通滤波和抽取均道.当雷达天线与细泥层地仗耦合较好时,中心频率1.6GHz和2.3GHz的雷达天线均能准确检测出深3cm左右、厚约2cm的空鼓,1.6GHz天线的极限垂直分辨率约0.5 cm.%As a rule, the thickness of wall painting plaster in Tibet is less than 10 cm. The ground penetrating radar (GPR) is applied to detection of delamination beneath wall painting plaster, It is quite a challenge task to remove directly the coupled noise waves in the radar profiling. So, size of the delamination can be determined accurately. Replica of Tibetan wall painting plaster is made and regular voids with different depths and sizes are set inside it. Then, the forward modeling detection is carried out in the replica in order to get appropriate parameters for acquisition of radar data, to find effective filters for signal processing, and to compare the performance of different antennas. Specifically to the RAMAC/GPR and its accessory software of Ground Vision, it is suggested that the depth of time window be about 3 ns and sampling frequency not less than 142 GHz, and that band pass filter and background subtraction are the two most useful filters in signal processing. When the antenna and the fine plaster are well coupled, both antennas at nominal center frequency of 1.6 GHz and 2. 3 GHz are capable of detecting void located at a depth of about 3 cm and a size of around 2 cm. The vertical resolution limit of 1.6 GHz antenna is near 0. 5 cm in size.
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