| 摘要 |
<p>PROBLEM TO BE SOLVED: To detect the occurrence of P and S waves of an earthquake from an obtained waveform by processing A/D-converted time-series data by a resonance-type digital filter with a different central frequency and multiplying one output by the other. SOLUTION: An A/D converter 21 and a microprocessor 22 are provided inside a seismometer, and the output of each directional vibration sensor 19 is A/D-converted by an A/D converter 21 via each amplifier 20. The time-series data are subjected to software processing in a microprocessor 22. More specifically, the time-series data are processed by a plurality of resonance-type digital filters with different central frequencies, both output waveforms are multiplied, and the envelope of the obtained waveform is observed. It is judged that P wave was detected when an envelope waveform obtained by processing the signal of the vibration sensor 19 in up/down directions exceeds a trigger level. It is judged that P wave was detected when the envelope waveform waveform obtained by processing the signal of the vibration sensor 19 in east/west and north/south directions exceed the trigger level, thus accurately detecting the generation of an earthquake.</p> |
