Hi Jürgen,
Am 25.01.2011 15:05, schrieb Jurgen Bartels:
How about 2 min samples 30 min apart for 24 hours?
I'm recording every 30 minutes for 2 minutes 0-100kHz
Those recordings I later can play back and make waterfalls for specific
frequencies. That allows me to zoom in on particular events afterwards.
However I don't see what happens within the 28 minutes waiting period. I don't
want to record 24h as it would take another 24h to produce waterfalls
Yes, that's another possible way but you always have to do some
additional work to get results from your recorded data. Running a
automatically generated spectrogram that gives you an overview of the
last hours on VLF and displayed on a self updating website available for
all (= grabber :-) ) is what i prefer here.
I am receiving these traces too, see the lower capture on
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html and
ignore the 600 Hz spaced QRM lines, caused by the Heidelbergs's tram SMPS...
I had a look there earlier, but the QRM lines made it hard to read.
In your case you could create a SpecLab plug-in that removes these lines before
they are painted. I did a similar thing for a different purpose. That would
make your grabber image easier to read.
Yes, i know about the auto notch function but i would notch the Alphas
as well if i do not make exceptions. The QRM lines are drifting so maybe
this isn't the perfect solution. I also know about Paul Nicholsons hum
filter but all these filters are misleading since the spectrogram
wouldn't show any more what the soundcard actually has do deal with and
what influences the RX sensitivity. The sferics could be blanked as well
to make the Alphas better visible... I rather want to concentrate to
find a remote RX location in the spring or summer 2011 :-) And actually
the main purpose is to display the activity in the Dreamers Band(s) :-)
In my SL instances running at 8970/6470/5170 Hz, all the filters that
improve the SNR are applied!
73, Stefan/DK7FC
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