| 摘要 |
PURPOSE:To detect a seismic wave by continuously calculating excellent frequency within a short time, by calculating the ratio of the index smoothing value of the value obtained by sampling an input vibration wave form to remove an offset level therefrom and the index smoothing value of differentiated or integrated wave form. CONSTITUTION:A sensor 1 detects the ground motion of the point where said sensor 1 is always arranged and converts the same to an electric signal which is, in turn, sent out to a control processor 4. A sampling part 11 takes in information at a predetermined time interval and performs the calculation of an offset level being the DC component of input data from the average value of informations corresponding to past several times. Then, on the basis of the value obtained by removing the offset level from a sampling value, an index smoothing value and the index smoothing value of a differentiated wave form signal are respectively calculated by the sampling part 11 and an acceleration converting part 12 to be sent out to a frequency calculation part 13. Excellent frequency is calculated from the ratio of both values and the arrival of a seismic wave is detected by a seismic wave detection part 14 when said frequency continuously exceeds a trigger level. |
