地震数据采集器自噪声测试实验研究

Experimental study on self-noise tests of seismic data-loggers

自噪声水平是地震数据采集器的重要性能评价指标,直接影响地震观测动态范围和数据质量。为完善相关研究,服务地震观测和仪器研发工作,该文以国内外主流地震数据采集器为研究对象,在不同实验条件下对其自噪声水平进行测试研究。结果表明:数据采集器实际有效位数小于AD转换位数,需通过实际自噪声测试结果表征仪器分辨力和动态范围;仪器实际自噪声及动态范围随量程减小而减小,与采样率设置无显著关系;仪器零点漂移受温度影响较大,具体表现为温度升高,零漂量增大,对观测影响程度增加;环境温度变化主要影响仪器低频段自噪声水平,最大影响超过5 dB。以上事实,在宽频带地震观测和地震计自噪声高精度测试中需予以关注,并适当采取保温措施。

Self-noise level is an important performance evaluation index of seismic data-loggers,which directly affects the dynamic range of seismic observation and data quality.In order to improve the relevant research,serve the seismic observation and instrument research,we take several seismic data-loggers commonly used at home and abroad as the research object and test self-noise level of them under different experimental conditions.The results show that the actual effective resolution of data-loggers is less than the number of AD conversion digit number,so it is necessary to characterize the effective resolution and dynamic range through the actual self-noise test.The actual self-noise and dynamic range of the instrument decrease with the reduction of the range,and the selfnoise level has no significant relationship with the setting of the sampling rate.The zero offset is greatly affected by temperature.Specifically,the amount of zero offset and the degree of influence on observation increase when the temperature rises.The influence of environmental temperature change on the self-noise of the instrument is mainly concentrated in the low-frequency band,and the maximum impact is more than 5 dB.In this fact,attention should be paid to the wide-band seismic observation and the high-precision test of the self-noise of the seismometer,and appropriate insulation measures should be taken.