First level calibrations of accelerometers

First-level ("primary",or "absolute") accelerometer calibrations are those performed at national metrology institutes (NMIs) for the calibration of reference accelerometers. The methods commonly used in such calibrations are briefly described. Some international comparisons of first-level calibrations are discussed. Common sources of error are examined, and illustrated with the results of a recent comparison which involved six NMIs from the Asia-Pacific region and one European NMI. Also discussed is the excellent agreement, for the range 30 Hz to 10 kHz, between several of the NMIs in the comparison, and the clear evidence of systematic errors in some of the results.