Sensors, Calibration of

Synonyms

Accelerometer; Response function; Seismometer; Seismometer damping

Introduction

The output of a seismic sensor, a seismometer or an accelerometer, is a time-varying voltage, which is related to the ground motion by a differential equation in the time domain or by a transfer function in the frequency domain. This transfer function or response function is characterized by a number of parameters, which are assumed to be constant, at least in the short term.

A seismic sensor will have calibration information given by the manufacturer. These specifications will be used to correct the seismic signal from the sensor to produce the true ground motion. If, e.g., for a given harmonic ground velocity X(ω), the output from the sensor is Y(ω), the amplitude response or transfer function A(ω) is defined as the ratio A(ω) = Y(ω)/X(ω), where ω is the frequency in radian/s. So, if A(ω) is known, the input (ground motion) can then be calculated as

$$ X\left(\omega \right) = Y\left(\omega...