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Date: Wed, 16 Jun 2010 22:03:40 +0100
Message-ID: <AANLkTil_hvxCz4JPhl_8V01xMCBJtt4cqGLX-bXI21bE@mail.gmail.com>
From: Roger Lapthorn <rogerlapthorn@gmail.com>
To: rsgb_lf_group@blacksheep.org
DomainKey-Status: good (testing) 
Subject: LF: 1.9kHz earth-mode tests today
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Today I modified my 4W VLF transmitter so it could send either a 10 wpm or
QRSS3 beacon signal. I also went out into the fields with my loop/preamp and
a PC with Spectran <http://www.sdrham.com/spectran.html> to receive it. For
the first attempt with a PC I went 0.3km away from home where the 4W signal
from the earth electrode "antenna" could clearly be received by ear. With
Spectran I could read the 10wpm CW signal with 20dB S/N in a 12Hz bandwidth,
if my understanding of the Spectran settings is right. There is an audio
recording here<http://sites.google.com/site/g3xbmqrp/Home/earthmode/300m.wav?attredirects=0&d=1>so
you can judge the S/N yourselves. This suggests that with QRSS3 (or
slower still) and really screwing the bandwidth down I should be able to do
much better. My problem is knowing how to calibrate the soundcard etc and
clearly I need a more stable source than my free running twin-tee audio
oscillator. I am a total novice when it comes to using QRSS and soundcards
using very narrow bandwidths.

73s
Roger G3XBM

-- 
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
G3XBM    GQRP 1678      ISWL G11088

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Today I modified my 4W VLF transmitter so it could send either a 10 wpm or=
 QRSS3=20
beacon signal. I also went out into the fields with my loop/preamp and a
 PC with Spectran<a href=3D"http://www.sdrham.com/spectran.html"></a> to=
=20
receive it. For the first attempt with a PC I went 0.3km away from home=20
where the 4W signal from the earth electrode &quot;antenna&quot; could cle=
arly be=20
received by ear. With Spectran I could read the 10wpm CW signal with=20
20dB S/N in a 12Hz bandwidth, if my understanding of the Spectran=20
settings is right. There is an <a href=3D"http://sites.google.com/site/g3x=
bmqrp/Home/earthmode/300m.wav?attredirects=3D0&amp;d=3D1">audio
 recording here</a> so you can judge the S/N yourselves. This suggests=20
that with QRSS3 (or slower still) and really screwing the bandwidth down=
 I should be able=20
to do much better. My problem is knowing how to calibrate the soundcard=20
etc and clearly I need a more stable source than my free running=20
twin-tee audio oscillator.
I am a total novice when it comes to using QRSS and soundcards using very=
 narrow bandwidths.<br><br>73s<br>Roger G3XBM<br><br>-- <br><a href=3D"htt=
p://g3xbm-qrp.blogspot.com/">http://g3xbm-qrp.blogspot.com/</a><br><a href=
=3D"http://www.g3xbm.co.uk">http://www.g3xbm.co.uk</a><br>
<a href=3D"http://www.youtube.com/user/g3xbm">http://www.youtube.com/user/=
g3xbm</a><br>G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088<br>

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