三地震计法精确测定地震计自身噪声研究

摘要

地震计自身噪声是地震计的一个重要技术指标,目前地震行业标准采用两地震计法,利用观测数据和地震计的传递函数,得到地震计自身噪声谱.两地震计法必须事先知道地震计的精确传递函数,而传递函数的测定误差给自身噪声的测定精度带来较大的影响.三地震计法在频域内用相关分析法得到地震计自身噪声谱,不需要知道被测地震计的传递函数,只利用三分向记录波形的互功率谱和自功率谱计算得出自身噪声谱.%Self-noise level is one of the most important parameters of seismometers.At present,according to seismic industry standards,self-noise power spectrum of seismometer is obtained from recording the same ground motion and transfer function of two-seismometer.However,the method is limited because it requires the accurate information about the transfer function of each seismometersmall errors in the transfer functions,which will cause relatively large errors in the calculated seismometer self-noise levels.Self-noise power spectrum of seismometer obtained from three-seismometer is proposed in the paper,based on correlation analysis of recordings from a common,coherent input signal in the frequency domain.The approach does not require accurate information about the transfer function of each seismometer,only in terms of cross-power spectra and autopower spectra of the recordings of the three seismometer connected to the same input signal.