An example of operation for a partly manned Antarctic geomagnetic observatory and the development of a radio link for data transmission

Abstract

The experience acquired from more than ten years of operation of an Antarctic geomagnetic observatory is described<br />along with the development of data transmission facilities. The observatory was deployed at the Spanish Antarctic<br />Station in 1996. The main instrument was an Overhauser magnetometer deployed in dual axis Helmholtz coils, a<br />δD/δI configuration. The site is only manned during the summer, with the magnetometer left recording throughout<br />the rest of the year. During the 2007-2008 survey the observatory instrumentation has been upgraded with a DMI<br />suspended triaxial fluxgate magnetometer, new sampling hardware and data logging software. Both sampling and<br />timing are carried out under the control of a PIC based microcontroller and GPS receiver. Data presentation, transmission<br />and archiving are performed under the control of a low power embedded PC. For real time access to the data<br />two options have been provided and rigorously tested during the last 10 years: METEOSAT and GOES Data Collection<br />Systems, and recently, a high frequency (HF) digital radio-link, using ionospheric propagation between<br />Antarctica and Spain, has been developed. This latest transmission system is being continuously upgraded, and it<br />would be possible to extend its application to other remote stations. Measurements have been made during the last<br />four years in order to determine the channel characteristics and its variability, mainly the multipath and Doppler<br />spread and the link availability for a given SNR in the receiver. These measurements are being used to design the<br />physical layer of a radiomodem intended to maximize the link capacity keeping the emitted power low.

Keywords

• geomagnetic observatories – geophysical instrumentation – data transmission - HF radio