VIRGO - E.G.O. ELF Monitoring station
Live data from CASCINA (PI), Italy, South Europe
Maintained by: Federico Paoletti - INFN Pisa (IZ5EBO), Irene Fiori - E.G.O., Giulio Ballardin - E.G.O. and Kamiel Janssens - University of Antwerp - Belgium. FFT processing by Renato Romero.
 


 
   
The Virgo detector for gravitational waves consists mainly in a Michelson laser interferometer made of two orthogonal arms being each 3 kilometers long. Multiple reflections between mirrors located at the extremities of each arm extend the effective optical length of each arm up to 900 kilometers. Virgo is located within the site of EGO, European Gravitational Observatory.

Untreated correlated magnetic noise from Schumann resonances across two or more detectors provides a fundamental limit on the sensitivity of stochastic searches.  One method of reduction is the use of magnetometers to subtract the correlated noise, where a Wiener filter scheme may be implemented. Effective subtraction requires precise measurement of global electromagnetic fields in areas with low local electromagnetic contamination.  

It is performed with Metronix MFS-06 magnetometers, from which the spectrograms of this page are also extracted and processed: the signal of the two magnetometers at VIRGO is transformed into a low sampling rate RAW stream (200 sample/sec) , and sent to Cumiana monitoring station (300 km away). There, a PC receives and processes it with SpectrumLab, in 4 different sessions and representations.



Signal coming from two Metronix MFS-06e induction coils: NS reception on top, EW reception on bottom.

Scroll time 40 seconds, FFT resolution 24 mHz. Service port: 8081.



Signal coming from two Metronix MFS-06e induction coils: NS and EW reception processed with complex FFT RDF.
The colors show the incoming signal direction.

Scroll time 40 seconds, FFT resolution 24 mHz. Service port: 8083.



Signal coming from two Metronix MFS-06e induction coils: NS and EW reception processed with complex FFT RDF and triple cardioid nulling pattern, green monochrome palette. Daily strips.

Scroll time 108 seconds, FFT resolution 6.1 mHz. Nulling pattern at 75, 107 and 156°. Service port: 8080. 



Signal coming from two Metronix MFS-06e induction coils: NS and EW reception processed with complex FFT RDF and triple cardioid nulling pattern, green monochrome palette. Daily strips. Hourly strips.

Scroll time 4.6 seconds, FFT resolution 97 mHz. Nulling pattern at 75, 107 and 156°. Service port: 8082.


Real time situation about lighting strikes in Europe. Courtesy of http://www.blitzortung.org

European map of lightning. It can sometimes be
                  off line for work in progress. If the map is not
                  displayed go to: http:// www.blitzortung.org


Unattended operations, signal conditioning, spectrograms and RDF functions are performed with SpectrumLab: https://www.qsl.net/dl4yhf/spectra1.html . Many thanks to Wolfgang Buscher for his support.

Free web counters

Return to www.vlf.it home page