Development of Data Acquisition System for Space Weather Study

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In this research, we have developed a real-time MAGnetic Data Acquisition System of Circum-pan Pacific Magnetometer Network, i.e. MAGDAS/CPMN system in Kyushu University. On the basis of the results, new fluxgate-type magnetometers and their data acquisition system from overseas sites to Japan will be constructed in the SERC, Kyushu University until the end of 2004. Magnetic field digital data(H+δH, D+δD, Z+δZ, F+δF) are obtained with the sampling rate of 1/16 seconds, and then the averaged data are transferred from the overseas stations to the SERC, Japan in real time. The long-term inclinations(I) of the sensor axes are measured by two tilt-meters with 0.2 arc-sec resolution. The temperature (T) inside the sensor bloc is also measured. The GPS signals are received to adjust the standard time inside the data logger/transfer unit.These data are logging in the Compact Flash Memory Card of 1 GB. Every day, the data logger at an overseas site generates a file containing averaged 1-see magnetic data (H,D,Z,F) and a file containing the averaged 1-minmagnetic data and inclination and temperature data (I,T) of the magnetometer sensor. The file size of the 1-sec data is less than 1.5 MB/day. The file-size of the 1-min data is less than 50KB. If the communication line at the site does not allow a fast-enough connection, the data logger sends only the 1-min file to the SERC every day ; if the connection is fast enough, the data logger sends both the 1-min file and the 1-sec file to the SERC every day. In fact, the data transfer does not have to be on a daily basis : That is, the data-transfer interval can be set to any value between 10 minutes and 1 day, depending on the condition of the following communication lines. The MAGDAS data can be transferred from the overseas stations to the SERC, Japan, by using three possible ways; special line for INTERNET, telephone line and Satellite telephone lines.