abstract

Automated amplitude and phase response of the complete seismometer-recording system is obtained from step inputs to the calibration coil. High accuracy is achieved by summing as many pulses as desired (to eliminate background noise) by a correlation technique and subsequent Fourier analysis. The only parameters required are the seismometer mass, the Cal-coil constant (referred to the center of mass if appropriate) and current, and the precise onset time of one reference calibration current, which are all very stable over long time periods. Application to the High-Gain Long-Period system at KIP yields the magnification curve from only six pulses with less scatter (< ± 5 per cent for periods larger than 20 sec) than routine steady-state calibrations.

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