Etna Radio Observatory
ETNA RADIO OBSERVATORY
Live data from NICOLOSI (CT), Etna Park, Sicily
Maintained by ERO Team

To see with google map where we are, click on this link: https://maps.app.goo.gl/P1pUWBymXCV3caccA 
(Lat. 37°37'52.45"N - Long. 15°1'20.26"E)





This monitoring station is located in Etna Park, which covers the area from the top of the volcano to the villages surrounding it. It is beautiful not only for its eruptions and lava flows, but also for the unique environment that surrounds it, rich in sounds, scents and colors. An enchanting landscape, protected by a park, that you cannot miss the opportunity to visit if you come to Sicily.


System 1: INDUCTION COIL EC200

The system uses a big dimesions self-made induction coil, named EC202: it stands for Ero Coil 200 mm lenght. It is made using mostly recycled material that has been suitably reworked. We are talking, for example, about 30 km of 0.22 mm enameled copper wire (about 20 kg) wound in two coils connected in series (and in phase). They have 11000 and 34960 turns, respectively, for a total of nearly 46000 turns. The two coils have an outer diameter of 25 cm, inner diameter 15 cm, length of 20 cm. They are mechanically glued in series to form a single coil. More technical details can be found on the observatory page: https://cataniact6.wixsite.com/etna-ero/ero-etnapark.

The total inductance, without a core, is 189 Henry. However, inside them is an iron core, consisting of 75 kg of individually resined 6 sq. mm bars. The core elevates the value of the final inductance by about 10 times, and obviously increases the sensitivity of the inductor.

ERO COIL EC200 specifications. 
  • Inductance: 1940 H (192 H without a core)
  • Resistance: 6.47 kOhm
  • Turns: 46000 (Series of two windings of 11000 and 34960 turns each)
  • Core: 2 meter long with iron rods (mixed 16.2 kg 50 cm long, and 58.8 kg 200 cm long )
  • Total weight: 97.4 kg


Rosario CATANIA is performing some characterization measurements.
Some details of the realization.

The rods are of two different lengths: 2 meters for the central part of the core and 50 cm for the more peripheral part, located directly under the coil. A low-noise preamplifier, built with an OP27G front-end as a balanced differential amplifier, provides the necessary amplification to drive the line input of the sound card directly. The power supply comes from a remote stabilized 12 V power supply via RG58 coaxial cable.


ELF and ULF MAGNETIC FIELD

Here below the first LIVE spectrogram, updated every hour. It shows the last 8 hours ELF activity (magnetic field), received by our coil.
    

     
Bottom part zooms on the 0,1 to 4 Hz range. FFT resolution 10,5 mHz, scroll time 40 seconds.


Following the same signal, in 1 hour strips.

   
This is the frequency range of schumann resonances, and a zone of deep interest to us, for the study of possible interaction of magmatic flow with the terrestrial magnetic field. FFT resolution 168 mHz, scroll time 4.6 seconds.

 
The last spectrogram from the coil shows the daily stripes, which are useful for comparing day-to-day activity in geomagnetic pulsation frequencies and finding any volcanic anomalies.
  

Scroll time 109 seconds and FFT resolution 10,5 mHz.



System 2: ORTHOGONAL LOOP

Double 50 x 50 cm squared orthogonal loop (IdealLoop H301) to receive ELF-ULF and VLF bands, from 8 Hz to 20 kHz. See article for construction details: http://www.vlf.it/feletti2/idealloop.html



Also located in the park, away from buildings, and powered remotely.


The first processing is broadband and includes frequencies from a few Hz up to 22 kHz:
 
Scroll time 11 sec FFT resolution 91 mHz. The signal is strongly disturbed by the unavoidable presence of network harmonics, generated by switchin power systems now in use everywhere. Therefore, the self-adaptive FFT filter included in spectrum Lab was used, achieving a good final result.


 RDF low frequency magnetic field. Color indicates signals incoming direction.

  
Scroll time 11188 mS , FFT resolution 84 mHz. No filter was applied on this RDF processing.


And by the same reception system, the hourly multi strips:
   Scroll time 4600 mS , FFT resolution 168 mHz. No filter was applied on this RDF processing.

System 3: GEOPHONE

Lastly, a vertical mass-suspended geophone. It is placed in the proximity of the computer. The signal is preamplified with single-stage low-noise OP27 opamp configured for 43 dB gain.


With it, earthquakes due to volcanic activity and paroxysms during eruptions are displayed. In addition to ordinary seismic activity up to more than 1000 km away. It is an important comparative reference in the analysis of signals received with induction coil.

Geophone Multistrip hourly representation:

Scroll time 4.6 sec, updated every hour. 

Here below the real time situation about lighting strikes in Europe. Courtesy of http://www.blitzortung.org/

Unattended operations, signal conditioning, spectrograms and RDF functions are performed with SpectrumLab: http://www.qsl.net/dl4yhf/ . Many thanks to Wolfgang Buscher for his support.
Automatic FTP process realized with SincBack: http://www.2brightsparks.com/

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