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From: John Rabson <john.rabson@numeo.fr>
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Date: Wed, 12 Oct 2011 15:23:14 +0200
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To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: noise on VK and earth dipole tests
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Hi Dimitrios,

Depending on what you are doing it may be inverse cube law (9 dB).

73 John F5VLF

On 12 Oct 2011, at 11:20CEST, Dimitrios Tsifakis wrote:

> Hi John,
>=20
> 2011/10/12 John Rabson <john.rabson@numeo.fr>:
>> Amongst other things, it depends on the geology.  G3XBM has managed =
5.6 km with 5 W RF at very low frequency.  On 87 kHz with 4W SSB (cave =
radio) in limestone, the best I know of is 1.6 km two way and 2.5 km one =
way in the French alps.
>=20
> Well, the S/N required for voice is much higher than that of QRSS30.
> With a puny 3 W of RF and QRSS30 it seems I can cover a distance of
> about 30 km and still have a S/N of 30 dB! Which implies that possibly
> (if the signal received is normal ground wave, similar to that from an
> above-ground antenna), with a spreading loss of 6 dB per doubling of
> distance and with a bit more juice, much greater distances may be
> covered.
>=20
>> It is always worth trying.
>=20
> That's the spirit in the amateur world of LF! :-)
>=20
> 73, Dimitris VK1SV
>=20
>=20