Research on method of extraction elevation angle from backscatter ionogram

Using the short-wave two-dimensional antenna array, the high-frequency (3MHz∼30MHz) backscatter sweep-elevation ionogram is obtained for the first time in China. Combining genetic algorithm and Otsu method, the signal region is extracted from the group path-frequency-energy three-dimensional ionogram, and the discrete point noise is eliminated by the connected domain labeling method. The Canny operator is used to obtain the nearest and farthest group path of the echo signal distribution corresponding to each frequency. On the group path-frequency-elevation three-dimensional ionogram, the elevation angle-group path distribution data of the corresponding frequency is acquired to obtain the elevation angle-group path point. The points are fitted by linear curve fitting, logarithmic fitting of the elevation angle, and logarithmic fitting of the group path. Finally, the error analysis of the fitted curve is carried out by the ionospheric data of the Qingdao Station. The results show that the curve obtained by logarithm fitting the group distance is in good agreement with the target curve.