From: Gerhard Hickl <gerhard.hickl@aon.at>
To: rsgb_lf_group@blacksheep.org
In-Reply-To: <4CD861D8.3070904@iup.uni-heidelberg.de>
References: <4CD861D8.3070904@iup.uni-heidelberg.de>
Date: Tue, 09 Nov 2010 20:33:43 +0100
Message-ID: <1289331223.1512.9.camel@gerhard-desktop>
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Subject: Re: VLF: Long time transmission on earth antenna
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Servus Stefan!

Yep, you can count on me too! I will get back from work tomorrow at
15:30z and I will have to use my "other" computer for this experiment
cause my usual VLF-grabber (old Toshiba notebook) will not be able to
handle your config-proposal....especially if the sample-rate calibrator
is on....

So you can expect me to be ready at latest at 16:00z.

Would be nice if you could inform us on the reflector, shortly before
you begin your transmission.

Looking forward to your experiment

73
OE3GHB
Gerhard


Am Montag, den 08.11.2010, 21:47 +0100 schrieb Stefan Sch=C3=A4fer:
> Dear VLF,
>=20
> The recent discussion about the optimal frequency and propagation on a
> given RX/TX distance is an interesting issue. Furthermore Markus/DF6NM
> and Paul Nicholson has demonstrated that it is possible to detect a 5
> uW EMRP signal in > 1000 km if the integration times are very long (>5
> hours) and the carrier is (VERY) stable in frequency.
>=20
> Since my earth antenna, currently 600m spaced earth electrodes and
> about 700 Ohm overall losses, seems to have a not too bad efficiency
> (remembering my 250 W DFCW-600 transmission was undoubly copied by
> Michael Oexner in 49.6 km on 8970 Hz) it could be possible to receive
> a long time transmission, GPS locked, in a very small FFT too. The
> advantage is that this antenna has not to be resonated and covers the
> whole VLF/LF spectrum with "suitable" efficiency. Thus it will be
> possible to try different TX frequencies and one can see if there are
> optimal frequencies for different locations, knowing that the antennas
> efficiency is a function of the frequency.
>=20
> Thus i want to do a VLF 24 hour non stop transmission, starting on
> 8970.00500 Hz. I have got some big lead acid car batteries (12 V / 300
> Ah in sum). First i want to try my small PA (300W) running at about
> 100 watts. For that, i will leave the car into the forest, over the
> night.
>=20
> I am still not sure if my GPS receiver is working in the forest but we
> will see.
>=20
> Note that this test cannot be compared to a kite antenna experiment.
> The signal is probably 30 dB weaker! Anyway it is worth a try, with
> longer transmission- and integrating times. Additionally the antenna
> may have some directivity. This would be interesting to be confirmed.
> S/N oriented stations may be preferred but everyone is invited to try
> to receive something :-)
>=20
> If some RX stations would receive this very weak signal, they will be
> able to provide informations at which time the signal level was
> strongest and when the S/N was best.=20
>=20
> Attached you find a SpecLab usr file with probably useful settings. I
> have choosen a FFT of 141 uHz (width of one FFT bin). If you want you
> can use this for reception.
>=20
> Please let me know if you are interested to participate in this test.
> It shall start in the late afternoon of wednesday, 10th November. The
> exact starting time is not sure since i have to be at work in the
> morning. Furthermore i want to reduce the earth rod losses even more
> by applying another 20 rods what will take some time. The experiment
> has to be during the week since on the weekend, to many people are
> crossing the way there...
>=20
> 73, Stefan/DK7FC
>=20