强震记录的采样与插值研究

STUDY ON SAMPLING AND INTERPOLATION OF STRONG MOTION DATA

摘要:

本文从频域和时域两方面对强震记录的采样和插值过程进行了研究。研究中将采样与插值当作一个信号转换系统,通过数值计算,求得和各种常用的采样和插值过程相对应的传递函数。通过对传递函数的进一步研究表明:采样和插值方式对强震记录数据处理的结果有重要的影响,发现采样过程相当于一个低通滤波器,可以滤除信号中的某些高频信息,而插值过程犹如一个高频噪声源,会在数字记录中引入某些伪高频分量。分析结果还表明:在相同的采样密度下,不等距采样方式具有较高的精度,而等间距采样方式能给出更宽的平坦的频率特性曲线;抛物线插值给出的传递函数结果要比线性插值的结果更精确,这对恢复数字信号中的高频成分具有重要的意义。

Abstract:

The effects of the sampling and the interpolation of strong motion data on the corrected accelerograms and integrated displacements are investigated in both frequency and time domains, It is found that the sampling of a record can be consideied as a low-pass filter which eliminates the high frequency contents in the record, but the interpolation of data does play a role of high frequency noise source which introduces high frequency noise into digital records. In is also founa that an unequally spaced sampling model will give a more accurate information than an equally spaced sampling model at the same sampling rate. But the latter will result in a wider range of flat frequency response than the former, than the former would. In comparison with the results given by the linear interpolation method, the parabolic one can generally provide with much better results, especially when a lower sampling rate is used.