Transfer standard sensors for disseminating traceable calibrations to the field

Transfer standards have an important role in calibration, in enabling traceability to be transferred across calibration facilities or physical locations. It is often the case in laboratory calibration, that the sensors best suited to achieving the optimum calibration accuracy, or measurement uncertainty, have different characteristics to those that need to be deployed in the field. Laboratory calibration techniques are often tailored to work with sensors of a specific type or form factor, and requirements on ruggedness and tolerance of a wide range of environmental conditions are usually of lesser importance under laboratory conditions. Conversely, a transfer standard is ideally suited to both laboratory and field environments. The Infra-AUV project is developing a complete calibration-chain solution to establish measurement traceability for IMS measurements, and consideration has therefore been given to the specification of suitable transfer standard sensors. The thought process behind this, and the infrasound sensors, hydrophones and seismometers ultimately proposed for designation as transfer standards will be presented, together with some characteristic calibration data.