加速度计及其融合高采样GNSS的低频信号测量特性研究

搭建了一套振动台系统，模拟不同频率振动信号对加速度计进行测试，并从信号功率谱密度和积分位移2个方面对其低频测量特性进行分析。实验表明，当振动信号频率高于0.05 Hz时，对加速度计信号进行高通滤波并积分能够恢复出较准确的振动位移；反之，随着信号频率的降低，积分位移误差增大。因此，为解决加速度计低频测量能力不足的问题，利用高采样GNSS与加速度计数据融合的方法，成功恢复了极低频振动信号。研究表明，振动台系统能够为地震监测研究提供良好的基础平台；加速度计准确恢复位移信号的低频下限在003~0.05 Hz左右，研究方法及结果可为加速度计频带的合理选择提供参考；同时，利用高采样GNSS与加速度计融合方法能够有效弥补加速度计低频测量能力不足的缺点，使地震低频位移更加准确可靠。

Low-Frequency Signals Measurement Characteristics of Accelerometers and Its Combination with High-Rate GNSS for Earthquake Monitoring

A series of vibration tests with different frequencies are conducted on a shake table to clarify the characteristics of low-frequency measurement. We analyze the results from two aspects: power spectral density of acceleration and displacement derived from integration of acceleration. We find that accurate displacement can be recovered by double-integration of acceleration(with appropriate high-pass filtering) on the condition that the frequency of vibration signal is above 0.05 Hz. In order to recover accurate displacements of vibration signals, especially in low frequency, we combine GNSS and accelerometer. The results show that this shake table system is an appropriate platform for earthquake monitoring studies; the lower limit of accelerometer low-frequency measurement is around 0.03-0.05 Hz, and the result provides reference for the proper choice of cut-off period for data processing of accelerometers as well. Meanwhile, the data fusion of GNSS and accelerometer data can combine the strength of each instrument and make the displacement derived more accurate and reliable.