lunedì 2 gennaio 2012


Significant time was spent during the last two years on the Pacific Ring of Fire, doing mainly radio related activities. The earth is permanently moving around, the surface of the lakes is never setled.

The volcano behind me, one of Papua New Guinea active volcanos, completelly destroys its environement statistically once at 20 years....and it is not a singularity.
earthquakes, related or not to volcano activities, are permanent.

Was working in Port Moresby, Papua New Guinea, during the last 7.3 magnitude quake, the 14th of December 2011. A 6.5 magnitude precursor occured, then the big one, followed by a lot of small 2-3 magnitude quakes in the following 8 hours.

Was luky : the only one dammage in my office was a cup of very good Indonesian coffee felt down from the table. But, was luky again: a complete CIAO RADIO H 101 monitoring hardware is running behind me.

To dismount an L101 active loop, to take the laptop, some cables and connectors , a spare battery and to drive the LandCruiser to a relative isolated place (a monastery at the boundary of the capital city) was my next step, taking half an hour. As a bonus, found here a poor , but still alive Internet connection.

An entry level ELF monitoring station was built in the next hour....fights with the laptop generated noise, with microphonic effects, with huge, permanent lightnings (it is wet season on Equator) . And was luky again... the L101 loop is suitable for this purpose: is rated -3dB@9kHz (its minimum usable frequency was never checked by me before).
As beginer in ELF measurements, got some good ideeas from Eng. Re Claudio....the most interresting and exciting was to monitor the level of an existing signal in the band to see if it varies durring the replicas of the main quake.
Found a nice BPSK signal on 19.8 kHz.

The spike (unmodulated carrier) on 19.2 kHz is generated in the laptop, it is constant regardless the settings of the audio card or other laptop hardware and has to be neglected.
Was trying to identify the surce of the BPSK signal on 19.8 kHz, rotating the loop. Had to use the minimum of the signal – the maximum was too flat – to find the direction. With the actual setup, the sense was impossible to be, two possibilities seems to be most probable: the US communication base at Clark, Philippines toward NE ,or the Australian Navy toward SW ....... both of them more than 2500km far from my site.

Huge lightning hits around me can be seen on the records.

The picture shows the recorded level of the 19.8 kHz BPSK signal.
Did not found any correlation between the signal level and quake replicas. The poor measuring resolution could be an explanation with the limited time or recording of 10 minutes , or simily that there is no correlation with VLF reception and eartquakes ....
The signal is nearly constant.

As begineer on ELF measurements, decided to send a 20MB recorded file durring the quake replicas to Eng. Re Claudio (and other skilled people, if requested) to found other issues not seen by me.

After postprocessing my records, Eng. Re got the next plot:

Despite their large duration (15-20 seconds), the ripples seems to be generated by the huge any evidence of earthquake influence on the received signal.
More accurate measurements will be carried out at my reentry in Papua New Guinea in the same weather conditions and in absence of earthquakes (I hope !), to compare the results.

Puiu , P29VIM, YO5BIM

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