Narayana P A, Ophir J
Ultrason Imaging. 1983 Jan;5(1):22-9. doi: 10.1177/016173468300500103.
The theoretical relationship between center frequency downshift and the spectral bandwidth was investigated for pulses with a sinc(x) spectrum propagating through lossy media. Power law and exponential models for frequency dependence of attenuation were used. Six target materials encompassing a range of attenuation parameters were used to verify the theoretical model. The frequency downshift data from these materials was used to calculate their respective attenuation parameters. It was shown theoretically and verified experimentally that for small frequency downshifts, the sinc(x) model yields the same material parameters as the Gaussian model. The choice of the model for the attenuation of the material was found to be inconsequential.
研究了具有 sinc(x) 频谱的脉冲在有损介质中传播时中心频率下移与频谱带宽之间的理论关系。使用了衰减频率依赖性的幂律模型和指数模型。六种涵盖一系列衰减参数的目标材料用于验证理论模型。这些材料的频率下移数据用于计算它们各自的衰减参数。理论上表明并通过实验验证，对于小频率下移，sinc(x) 模型产生与高斯模型相同的材料参数。发现材料衰减模型的选择无关紧要。
