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ULF MONITORING SYSTEM 
FOR EARTHQUAKE MAGNETIC
PRECURSORS STUDY

ULF MONITORING SYSTEM FOR EARTHQUAKE MAGNETIC PRECURSORS STUDY

ULF monitoring system is intended for earthquake magnetic precursors study in low-noise areas. It consists of three search-coil magnetic sensors LEMI-30 and communication unit CAM .

The induction sensor LEMI-30 designed for the study of magnetic field fluctuations in the frequency band 0.01 ... 30 Hz in land conditions. It can be used both as a part of a computer measuring and registration equipment and autonomously with any analogue measuring device. The communication unit CAM serves as a power supply and as an interface unit between sensors and PC. It contains also digitizer (24 bits ADC) and satellite synchronization (GPS) of sampling.


Main Technical Parameters of LEMI-30

Frequency band of received signals 0.01..30 Hz
Transformation factor frequency response
from 0.01 Hz to 1 Hz
from 1 Hz to 30 Hz
20´f mV/nT*
20 mV/nT
Auxiliary output gain 20 dB
Full band transformation factor error £3 dB
Magnetic noise level at
0.01 Hz,
0.1 Hz,
1 Hz,
10 Hz..30 Hz

£20 pT´Hz-1/2
£2 pT´Hz-1/2
£0.2 pT´Hz-1/2
£0.04 pT´Hz-1/2

Mains interference rejection >60 dB
Power consumption (121)V,  7.5mA
Temperature range of operation minus 10 ¸ +50oC
Dimensions of one LEMI-30 sensor l = 900 mm;
Æ =100 mm
Mass of one LEMI-30 sensor 6.5 kg


Last modified: 24-12-2004

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