| 摘要 |
PROBLEM TO BE SOLVED: To calibrate an internal clock of a digital seismograph installed in a remote uninlabitated place using a GPS signal from a satellite. SOLUTION: The strong-motion seismograph is provided with a unit 10 for receiving a GPS signal and forming a calibration signal identical to the time signal of NHK. A calibration signal formed in the unit 10 is transmitted to an automatic calibration unit 4a built in the internal clock of a digital seismograph for the purpose of calibration. According to the arrangement, the internal clock of the digital seismograph installed in a region, where radio wave of NHK can be received, can be calibrated. |
