时频面的双曲网格剖分及其应用

Hyperbolic bins subdivision in the time-frequency plane and its application

地层介质对地震波的吸收衰减是传播时间与频率乘积C的函数。在与吸收衰减相关的处理过程中(如品质因子估计、Gabor反褶积等),经常涉及时频面的双曲网格剖分,不同的剖分方式对处理效果有不同的影响。基于此给出了4类网格离散采样方式,分别具有等步长(等间隔网格)和变步长特征(等长度、等衰减和等面积网格),并对4类网格离散采样的采样特点进行了对比分析。在网格数固定的情况下,具有变步长特征的网格在低C值区加密采样、在高C值区稀疏采样。模型数据测试和实际资料应用表明,衰减记录时频谱振幅的衰减曲线在低C值区间具有较好的稳定性,如果利用变步长网格对时频谱进行统计,可以得到更多合理可靠的采样数据点,更利于振幅曲线的线性拟合。

Absorption attenuation is a function of a variable C,the product of proporgation time and frequency.The distribution of hyperbolic bins in time-frequency plane is often referred in processing about absorption attenuation（e.g.estimation of quality factor and Gabor deconvolution）.Different distributions have different effects on processing.Based on different assumptions,4types of discrete sampling are defined,which are characteristic of fixed-step sampling（fixed-interval hyperbolic bins）and variable-step sampling（fixed-length,fixed-attenuation and fixed-area hyperbolic bins）.When the number of bins is set,variable-step sampling can densely sample in the region with low value Cand sparsely sample in the region with high value C.Modeling test and actual data application shows that the amplitude attenuation curve is more stable in the region with low value Cthan that of in high value C.In that case,if amplitude curve is estimated by variable-step sampling in time-frequency spectrum,more reasonable and reliable specimens can be achieved,which is beneficial for linear fitting of amplitude curve.