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Date: Tue, 25 Jan 2011 16:09:15 +0100
From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= <schaefer@iup.uni-heidelberg.de>
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Subject: Re: LF: What freq. list can you recommend
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Hi J=FCrgen,

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
>   =20
Yes, that's another possible way but you always have to do some=20
additional work to get results from your recorded data. Running a=20
automatically generated spectrogram that gives you an overview of the=20
last hours on VLF and displayed on a self updating website available for=
=20
all (=3D 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 an=
d
>> ignore the 600 Hz spaced QRM lines, caused by the Heidelbergs's tram SM=
PS...
>>     =20
> 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 wo=
uld
> make your grabber image easier to read.
>   =20
Yes, i know about the auto notch function but i would notch the Alphas=20
as well if i do not make exceptions. The QRM lines are drifting so maybe=
=20
this isn't the perfect solution. I also know about Paul Nicholsons hum=20
filter but all these filters are misleading since the spectrogram=20
wouldn't show any more what the soundcard actually has do deal with and=20
what influences the RX sensitivity. The sferics could be blanked as well=
=20
to make the Alphas better visible... I rather want to concentrate to=20
find a remote RX location in the spring or summer 2011 :-) And actually=20
the main purpose is to display the activity in the Dreamers Band(s) :-)=20
In my SL instances running at 8970/6470/5170 Hz, all the filters that=20
improve the SNR are applied!

73, Stefan/DK7FC