Low-Frequency Calibration of Accelerometers by Rotation in the Gravitational Field at NIST

We present a low-frequency accelerometer calibration system based on rotation in the gravitational field. Example characterizations of three accelerometers from (0.01 to 1.5) Hz with an uncertainty analysis demonstrate $k=2$ magnitude and phase uncertainty of <0.1 % and <0.2°, respectively. This rotational system complements the linear shakers in the NIST Primary Vibration Calibration Laboratory by improving uncertainty in the range of overlap and extending accelerometer calibration capability to lower frequencies. We demonstrate a magnitude comparison between the linear and rotational approaches, showing agreement to within the rotational calibration uncertainty of <0.1 %.