| 摘要 |
PURPOSE:To calculate momentarily and continuously the variation of a predominant period of an earthquake wave by calculating an exponential smoothing value of observation outputs whose natural periods are different, from two sets of seismometers. CONSTITUTION:Sensors 1, 2 for detecting a ground motion have each different natural frequency, always detect a ground motion of a spot where they are installed, respectively, and send out signal to a processor 20 through amplifiers 31, 32 and buffer amplifiers 41, 42. A sampling means 6 samples information at a prescribed time interval (1/50-1/150 sec), calculates an offset level being a DC portion of an input data from an average value of sampling information of a prescribed frequency portion in the past and eliminates it. An exponential smoothing means 7 smoothes said value, and a predominant period is calculated by the natural frequency of each sensor and the exponential smoothing value by a predominant period calculating means 8. A predominant period output means outputs the predominant period to the outside. |
