Envelope-to: dave@picks.force9.co.uk
Delivery-date: Tue, 24 May 2005 18:52:25 +0100
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Date: Tue, 24 May 2005 19:52:43 +0200
From: Wolf DL4YHF <dl4yhf@freenet.de>
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To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: reception with multiple antennas
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Hi Stewart,

An impressive idea - sounds a bit like radio astronomy on LF, using an 
interferometer !

One problem I see for a practical implementation is the internet 
connection - last not least because on some quiet "remote" sites there 
is no internet at all, or only through a slow modem connection. I played 
with the windows socket services some time ago, trying to get a reliable 
audio link in "almost real time" running, but got entangled in red 
tape... it may be simpler these days, but I honestly haven't got a clue yet.
For a start, we either try to exchange the audio samples as simple 
decimated audio files (via manual or automated cyclic FTP, etc), or find 
someone with in-depth experience in WAN / internet programming.
Another, possibly simpler "local" approach which would not rely on the 
internet, is using cheap FM links to combine signals received from 
various receiving sites separated a few dozen kilometers from each 
other, and use a PC / soundcard with multiple inputs. This would allow 
almost-real-time reception, good for two-way CW attempts ;-)

For the test recordings, which file format would you prefer ... 
bandwidth / sampling rate, complex or real sample pairs, etc ?
I wanted to add a decimated audio logging feature in the WOLF GUI, 
possibly using the JASON file format (which is supported by at least two 
other programs already), or something in that style.
The next chance to make a few recordings would be on Thursday evening, 
or next weekend, though the "QRN forecast" doesn't look very promising.

73,
 Wolf  DL4YHF .