Usually, a sine wave is used to excite both sensors.
When the sine wave is being generated on the shaker, the output signals of the reference sensor and sensor under calibration are measured.
After that, sensitivity is calculated by the formula:
Sc – sensitivity of the sensor under calibration;
Sr – sensitivity of the reference sensor;
Xc – output of the sensor under calibration;
Xr – output of the reference sensor.
The procedure repeats itself on five or six frequencies distributed through the frequency range of the sensor under calibration, one frequency is the minimum, one the maximum and one the reference frequency of the accelerometer.