FFT和DFT在地震数据采集器幅频特性测试中的应用

Applications of FFT and DFT in amplitude-frequency characteristic test of seismic data recorders

在进行地震数据采集器的幅频特性测试中,当标定信号频率稍高时(约为采集器采样率1/5以上),采集器输出的正弦波形发生畸变,无法人工读取正弦波峰值.为了解决该问题,本文提出了基于离散傅里叶变换(DFT)的积分恢复算法,将该方法与快速傅里叶变化(FFT)谱分析方法同时应用于一台高精度地震数据采集器的幅频特性测试数据处理.结果表明这两种算法均能标准化、高精度地完成采集器幅频特性标定数据的计算.其中基于DFT的积分恢复算法的计算程序操作简单,能够高效率地完成数据采集器的幅频特性检定工作;并且该方法还可以应用于地震数据采集器的线性度测试.

During the process of amplitude-frequency characteristic test of seis-mic data recorders,when the frequency of calibration signal reached one-fifth of the sampling frequency of seismic data recorder,we cannot manually get the peak-value of output sine-wave by seismic data recorder due to distortion of sine-waveforms.In order to solve this problem,this paper proposed a DFT （discrete Fourier transformation ）-based numerical integration method.Then FFT （fast Fourier transformation ） method and DFT numerical integration method were used to compute real amplitude-frequency characteristic test data of one high-precision seismic data recorder.The result shows that these two methods are high precision and standardization,and can compute the calibrating data of amplitude-frequency characteristic.Compared with FFT method,DFT-based numerical integration method is simple to operation.And it can also be applied to linearity test of seismic data recorders.