【摘要】 地震仪的动力学特性通常是用频率域中的幅频特性和相频特性表示的,但是,合成地震图和由地震图恢复地面的真实运动都是在时间域中进行的,这就需要知道地震仪的时间特性(脉冲响应特性)。从理论上讲,可以由实测地震仪的幅频与相频特性通过快速傅里叶变换(FFT)用数值方法把时间特性计算出来,但是,计算结果表明,误差很大,尤其是在初动部分。因此,计算地震仪的时间特性应该从地震仪的传递函数出发,通过拉普拉斯反变换求得。 目前,我国基准地震台上使用三种类型地震仪:直接耦合地震仪、电流计记录地震仪和电子放大地震仪。前两种地震仪,它们的运动方程和传递函数已知,传递函数系数可以通过经典的分段标定方法求得。但是,对于电子放大地震仪,由于引入电子线路,首先必须确定电子线路部分的传递函数及其系数,然后再求出它们的频率特性和时间特性的解析表达式。 作者根据DD-1和DK-1型电子放大地震仪的分段标定结果,用复曲线拟合方法求出了它们的传递函数,并由传递函数导出了频率特性和时间特性的解析表达式,计算出了DD-1和DK-1型地震仪的幅频特性曲线、相频特性曲线和时间特性曲线。更多还原

【Abstract】 The dynamic response of a seismograph is usually expressed by means of amplitude- and phase-frequency responses in the frequency domain, but the construction of the synthetic seismogram and the restoration of the true ground motion from sei-smograms are carried out in the time domain. Therefore, it is nesessary to know the time response (pulse response) of the seismograph. Theoretically, the time response can be numerically computed by using the Fast Fourier Trnsform (FFT) from experimental amplitude- and phase-frequency response data, but results show that the computation error of time response is larger, especially in the initial motion range. Therefore, in the computation of the time response of a seismograph it is better to use the transfer function, from which the time response may be obtained by the inverse Laplace transformation.At present, three kinds of seismographs are used at Chinese seismic stations. They are the direct-coupled seismometer, the galvanometric seismograph, and the electronic seismograph. For the first two kinds the equations of motion and transfer functions are known. The coefficients of the transfer functions are determined by means of classical step-by-step calibration. For the electronic seismographs, such as the type DD-1 and type DK-1, however, the coefficients of the transfer functions of the electronic circuits have to be determined first before determining the analytic expression of their amplitude- and phase-frequency responses and the time responses.In this paper the transfer functions of the type DD-1 and type DK-1 electronic seismographs are determined by applying complex curve fitting on the basis of step-by-step calibration. Analytic expressions of frequency and time responses of the type DD-1 and type DK-1 seismographs are derived from their trasfer functions and their amplitude- and phase-frequency response curves, and time response curves are given.更多还原