中值反差滤波在返回散射电离图前沿提取中的应用

Application of Median-contrast Filtering on Extracting the Leading Edge from an Backscatter Ionogram

返回散射电离图包含着丰富的电离层状态信息,能够为以电离层为传播媒介的高频应用系统提供实时的电离层参数,其中一个重要的参数便是最小时延线,即前沿。本文提出了一种新型的方法用于返回散射电离图的信息判读,方法利用中值反差滤波对返回散射电离图进行过滤,保留电离层的前沿位置信息,然后利用形态学图像处理中的腐蚀和膨胀运算将电离层的前沿描迹提取出来。此方法避免了传统算法中繁琐的同频干扰抑制和噪声去除操作,整个处理过程更加简易明了。结果显示,这种方法不但可以提高处理速度,而且还能够很好地提取出返回散射电离图前沿的位置,能够满足工程应用的实时性,具有良好的应用前景。

The ionosphere plays an important role in high-frequency radio application systems. Backscatter ionograms contain useful information of the ionosphere and the leading edgeson them are important parameters. A new technique is proposed to extract useful parameters from backseatter ionograms. The algorithm is based on the median-contrast filter. Firstly, the filter is utilized to process the ionogram to obtain a clearer leading edge. Then, the leading edge is extracted by the erosion and dilation operations in binary mathematical morphology. This algorithm circumvents the process of reducing the radio frequency interferences and random noises and appears concise. The results show that this algorithm is effective to ohtainthe leading edge from an backscatter ionogram.