Magnetometer calibration: a joint initiative of Defence and AGSO

Abstract

The Australian Department of Defence and AGSO aimed to provide a calibration facility for three-component (vector) magnetometers and thereby a cost-effective service for defence and geoscientific purposes. Defence was the main provider of funding and would be spared the expensive and long-winded process of sending its instruments overseas for calibration. Australia would gain from having a world-class facility available to all magnetometer users. Three sets each of four coils are mounted orthogonally and connected to programmable current sources enabling the creation of magnetic fields between 0 mT and 100 mT in any direction. A sequence of field values is generated and compared with the corresponding outputs of the magnetometer under test. The system computer then automatically prints the main parameters describing the instrument?s sensor angles, sensitivities, linearities, and test conditions. Background field variations over the measurement period are subtracted. Our system is capable of generating fields to a magnitude accuracy of 20 ppm and a directional precision of about 10 seconds of arc assured by checking the generated fields with a standard scalar (proton) magnetometer. The Defence Department?s needs and its policy of encouraging general use have enabled AGSO, in close collaboration with its suppliers, to create a unique facility for terrestrial and space exploration, for general scientific research, and a foundation for future client needs. Already AGSO is developing, with funds from the CRC for Satellite Systems, the capacity to magnetically characterise FedSat which will carry a three-component fluxgate magnetometer into polar orbit early next year. FedSat is an Australian Government Centenary of Federation project.