Hello Eddie,
Well, your noise floor below 5 kHz seems to look much better than here.
I started some ULF tests last year but have (temporarely!) stopped due
to the bad SNR and other more important projects. If you have some FETs
left, why not build a ELF probe? In a first thought, i would remove the
HPF and increase the C values of the LPF by a factor 30, to get a cut
off frequency of about 500 Hz. But there are existing designs which may
work better, no idea.
73 and tell us if you got ZEVS!
Stefan
Am 04.05.2011 15:06, schrieb qrss:
Hello Stefan
I was prompted to take a look 'down low' a couple of weeks ago when
SM5LE said, look 'Schumann resonances'. You will be surprised that I
am using your E-Probe, unmodified. I wasn't expecting to see much so I
was surprised by the results.
Have I seen Schumann resonances? I am not going to say, proof needs
time of observation.
Information about the signals and phenomena down there is scarce, I
have heard mention of 90Hz for submarine comms so many thanks for the
link I have removed my LPF and shifted the window up to take a look on
82Hz.
EDIT
Carrier at 80.2Hz, 75.2Hz and 64.24Hz which would seem to be a
harmonic of the 32Hz and likewise the 16Hz a sub harmonic of 32Hz.
My searches for information have certainly taken me to Renato's page,
I was showing a link to his site as a 8.9kHz Grabber, since looking at
his site I have moved him into a Link class of his own.
There have been questions about the pulses of interference at ULF.
When we look at our VLF Wide displays the Sferics seem to peter out
around 3kHz, (your filter is doing its job). However I have used the
0....50Hz view to prove to my own satisfaction that Sferics are still
going strong down to 0Hz. Probably removing the 3kHz cut of would
cause havoc down there.
There are several carriers of unknown origin, maybe due to my urban
location which I can investigate. Any thoughts of what runs at 32Hz
would be welcome, I am pretty sure it comes down from the antenna.
Well, when there are no tests on 8.9kHz I can keep interested.
73 Eddie
On 04/05/2011 12:14, Stefan Schäfer wrote:
Hello Eddie, VLF,
Your additional grabber windows are interesting. Remembers me to the
site of Renato Romero ;-)
What antenna do you use for displaying the range of 0...50 Hz? My
probe circuit has a high pass filter with an edge frequency of about
3 kHz. So if your QRM below 3 kHz is not to strong, you may remove
that and get better signals on ELF. Have you ever received the ZEVS
at 82 Hz? http://www.vlf.it/zevs/zevs.htm
73, Stefan/DK7FC
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