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由于干扰波及反射波的频谱或视波长范围都部分地互相重合,所以无论是用时间域的频率滤波或空间域的组合法滤波都不能奏效。但是在频率波数域里却可以用二维滤波将它们分开,从而提高信噪比和分辨率。本文研究了单炮记录波组的特征及相应的振幅谱。指出根据振幅谱可以正确地制定二维滤波的参数。二维滤波可以提高单炮记录上反射波的连续性、分辨率并使层次增多。对于滤波后的剖面虽连续性有改进,但也有窜相位的现象。故应选择适当的衰减参数,首先取得良好的单炮记录再进一步处理。由于假频效应的存在,会出现假频的能量区,同时切口滤波及扇形滤波的作用也会对二倍的假频区起作用,还可能影响反射波。为此,需用特殊的选件加以限制。
Since both the frequency spectrum of the interference wave and the reflection wave or the wavelength range of the reflection wave partially coincide with each other, both the frequency filtering in the time domain and the combination filtering in the space domain can not work. However, they can be separated by two-dimensional filtering in the frequency wavenumber range to improve signal-to-noise ratio and resolution. In this paper, the characteristics of single shot recording wave group and the corresponding amplitude spectrum are studied. It is pointed out that the two-dimensional filter parameters can be correctly formulated according to the amplitude spectrum. Two-dimensional filtering can improve the continuity, resolution and level of reflections on single shot records. Although the continuity of the filtered profile has improved, but there are channeling phenomenon. Therefore, we should choose the appropriate attenuation parameters, first of all to obtain a good single shot record further processing. Due to the aliasing effect, the energy region of the aliasing occurs, and the effects of the notch filtering and the fanning filtering also work on the double aliasing frequency region and may also affect the reflected wave. To do this, special restrictions apply.