Hi Dimitris,
Am 20.10.2011 02:20, schrieb Dimitrios Tsifakis:
I haven't given a lot of thought on the circuitry to
connect the sound card to some sort of active antenna. Are there any
suggestions on how to proceed?
This is what i use on my grabber:
http://www.iup.uni-heidelberg.de/schaefer_vlf/8,97kHz%20active%20E%20field%20antenna%20by%20DK7FC.jpg
Also, are you using externally clocked
soundcards?
Mostly they are locked internally, i.e. by SpecLab. You have to lock on
a reference frequency to correct the soundcard xtal drift. This can be
done by using a small GPS module (running from the 5V of the USB) that
has a 10 khz output. You can see the 10 kHz line in my wideband
spectrogram on the bottom of the grabber site.
Alternatively you can lock on a MSK transmitter (military) if one is
available. In VK, there is NWC on 19.8 kHz which is in OG78BE (locator).
You should have good reception of that transmitter since we can see it
here in 1 Hz as well.
I suppose, once you get into the uHz territory, having an
external super stable clock feeding the soundcard is a must?
YES!
73, Stefan/DK7FC
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