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REPORT

about the installation of data transmission system at the magnetic observatory of the Ukrainian Antarctic station Academician Vernadsky (observatory code AIA).
Data assessment at Y.Nakalov (refnak@isr.lviv.ua)

Three-components flux-gate magnetometer LEMI-008 was installed April, 1, 2000 in Variometer Hut of the magnetic observatory Argentine Islands at Ukrainian Antarctic station Academic Vernadsky. This magnetometer has possibility to record the Earths magnetic field variations with sampling rate of 1 s and sensitivity threshold of 0.1 nT. Magnetic axes orientation is H, D, Z. Magnetometer LEMI-008

During all this time the device worked without any kind of problems. The baselines of H and Z-components of LEMI-008 magnetometer for year 2000 are given in the Attachments 1, 2. The jump in the baselines is caused when the magnetometer sensor was replaced at better peer in the hut (see Fig.1).

Taking into account that the obtained from Academic Vernadsky station data proved the correspondence of baselines variations to INTERMAGNET standard, in the autumn of year 2000 LCISR and BGS came to agreement to transmit to LCISR the equipment for data loading and transferring via satellite. With joint assistance of BGS, USGS and INTERMAGNET LCISR engineer Ye.Nakalov passed successfully the probation period in BGS with the aim to learn the equipment and software. After his return the search of the proper place at the station was done for the possibility to install the transmitter antenna. It became clear that the elevation angle of METEOSAT satellite visibility is closed with the continental mountains. Then USGS efficiently changed the BGS transmitter to the system oriented to GOES-E satellite and Ye. Nakalov managed to learn it in proper time.

In January, 2001 in Fiberglass Hut of magnetic observatory Argentine Islands the equipment for satellite transmission of magnetometer data of the type 3455A GIM (SYNERGETIC INTERNATIONAL), which provides the communication via geostationary satellite GOES-E, was installed (see Fig.2). The high-frequency 10 W 3421A GOES transmitter with the digital frequency tuning assures the operation according to the established transmission mode and within the allowed communication channel.

The established parameters of 3421A transmitter are:

ARGENTINE ISLANDS
AI3455.V04
GOES CHANNEL 27
GOES LD.75C122B2
TRANSMIT TIME: 00 10 00

6ICON.JPG (6278 bytes)

The equipment of the satellite data transmission 3455A GIM and the transmitting antenna are placed in the Fiberglass Hut which is 50 m distant from the measurement pavilion Variometer Hut, were LEMI-008 magnetometer is placed. The antenna was fixed to the wall of the Fiberglass Hut what allowed to protect it against the winds which have the corresponding prevailing direction there (see Fig.3).

The transmitting antenna has the following orientation:

Azimuth 11.87 (to West)
Elevation angle over horizon 15.99.

 

7ICON.JPG (5251 bytes)

In the course of the matching of 3455A equipment with LEMI-008 magnetometer the necessary modernization of LEMI-008 was realized:

bullettransmission of the analog signals of LEMI-008 magnetometer X, Y, Z components to 3455A GIM system was provided;
bulletcontrol program of LEMI-008 was corrected for data operating control. The result of X, Y, Z components and temperature measurements every second is transmitted via serial channel to connected computer in ASCII code (transmission rate is 9600 baud, 8 digits).

The functional diagram of the equipment 3455A GIM and magnetometer LEMI-008 installation in Variometer Hut and Fiberglass Hut is given in Attachment 3.

After installation of 3455A GIM, from March, 11, 2001, the permanent transmission of the LEMI-008 magnetometer data was begun, which are cumulated on FTP-server after processing in the Canadian information center.

The received from 3455A GIM equipment data is given in telemetric digits (TMD) which is necessary to transform into magnetic field values (nT). It was realized by the TMD data comparison with nT data received directly from magnetometer LEMI-008 for the same period by e-mail communication (Attachments 4,5,6).

On the first diagram the fragment of magnetic data record transmitted from 3455A GIM is shown (Att.4).

On the next two diagrams (Att.5,6) the same data fragment is shown which was received from the magnetometer LEMI-008 by station e-mail transmission every second (Att.5) and averaged for every minute (Att.6).

All diagrams are synchronized by time. On the diagram of Att.5 one can see the high level of the interference at the station territory. In particular, the regular minute marks with amplitude of ~0.4 nT come from the unknown source.

For comparison the every minute records of H, D, Z components transmitted via 3455A equipment and averaged for one minute data from LEMI-008 scaled between each other are taken (Att.7, 8,9). One may note that the difference between two sets of data gives comparatively small dispersion between data from 3455A and LEMI-008.

The calculated averaged transfer coefficients (3455A/LEMI-008) are the following:

Channel H: 42 TMD/nT
Channel D: 40 TMD/nT
Channel Z: 39 TMD/nT.

The average dispersion of the coefficients is no more than 1 TMD.

The example of transfer coefficient dispersion for D channel is given on the diagram (Att.10).

The supposed reasons of the dispersion of the transfer coefficient average values can be the following:

bulletStray pick-up to analog communication line of 50 m length between magnetometer and 3455A unit;
bullettransformation errors of ADC system of 3455A GIM unit;
bulletdifference of transfer coefficients of the magnetometer channels.

It is necessary to note that at the obtained average value of transfer coefficient ~40 TMD/nT the maximal deviation is not more than 4 TM digits, what corresponds to the specified resolution threshold 0.1 nT of the magnetometer. So, it is recommended to accept the average mean of the transfer coefficient equal to 40 TMD/nT for every component and to transform the information transferred now (in TMD) to www into readings by the magnetic field (in nT).

The work planned for the future to rise the magnetic data quality.

  1. To provide the reception of the digital magnetometer data with 3455A GIM equipment via serial channel what will permit to transfer to INTERMAGNET system the data measured directly with LEMI-008 magnetometer and to exclude the interference inducing to analog connection channel between the magnetometer and the transmitter.
  2. To install the equipment permitting to set the time every 24 hours in the automatic mode by GPS and to control the transfer parameters of 3455A equipment.
  3. To modernize the software of LEMI-008 magnetometer to make possible the formation of data files which are necessary for transferring to 3455A.
  4. To organize the possibility of the distant control of LEMI-008 magnetometer.
  5. To eliminate the minute interference with 0.4 nT amplitude and 3 s duration which was observed in LEMI-008 data.

January-February 2001, Vernadsky Antarctic Station

Baseline Z component LEMI-008 for 2000 year

Baseline Z component LEMI-008

Publications

1 Pulsation polarization study Pc3, Pc4 at the Antarctic Station Academician Vernadsky (sunflower effect) Radiophysics & Radioastronomy, V. 5, No 2, 2000, 118-124 (in Russian) A.Zalizovsky
Yu.Yampolsky
V.Korepanov
I.Dotsenko
 
2 " " , . 2, 1998, . 124-129 V.Korepanov
I.Dotsenko
et al.
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Last modified: 06-12-2012

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