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Date: Sat, 19 Sep 2009 10:52:12 +0100
Message-ID: <9afca2640909190252s23c96e1bh33bdcf0178efc277@mail.gmail.com>
From: Roger Lapthorn <rogerlapthorn@gmail.com>
To: rsgb_lf_group@blacksheep.org
DomainKey-Status: good (testing) 
Subject: Re: LF: RE: 500kHz QRPp WSPR overnight
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Dear Jim (et al),

Thanks for this interesting analysis. It does indeed suggest *plenty* of
scope for improvement in the coming months.

As I've said several times in the last week, I'm gobsmacked that anyone,
apart from G6ALB 3kms away, is able to hear me with the set-up I have. The
500kHz WSPR beacon will run one more time overnight tonight  then it will be
off for 2-3 weeks.

My wife is wanting her dressing table back as the tiny ATU is sitting on it
and tuning is very sharp; every time she puts anything down I have to check
the antenna current is peaked :-))

You know I'm like a kid: I get *so* excited looking at the spots and
thinking about gradually making improvements and seeing my coverage extend
on 500kHz.

My wife just humours me!

73s
Roger G3XBM


2009/9/19 James Moritz <james.moritz@btopenworld.com>

> Dear Roger, LF Group,
>
> It is interesting to make an estimate of what G3XBM's ERP might be...
>
> The noise level at M0BMU during relatively quiet daytime conditions I
> estimate to be of the order of 3uV/m in the 2.5kHz WSPR reference bandwidth.
> The reported SNR gets up to about -25dB, making the signal level from G3XBM
> about 0.18uV/m.
>
> ERP = (Ed)^2 / 49; with E = 0.18 x 10e-6, d = 69000m , ERP is about 3uW
> with only "geometric spreading" propagation losses. But there is some
> additional reduction in field strength due to ground wave propagation
> losses, perhaps 3dB with "good" ground, so the ERP would then become about
> 6uW. Diffraction losses due to the curvature of the earth are negligible at
> this distance.
>
> Obviously, this could be +/- several dB due to various uncertainties, but
> should be of the right order of magnitude. Plenty of potential for
> improvement then!
>
> Cheers, Jim Moritz
> 73 de M0BMU
>
>


-- 
-------------------------------------------------------------
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
G3XBM    GQRP 1678      ISWL G11088

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Dear Jim (et al),<br><br>Thanks for this interesting analysis. It does ind=
eed suggest <u>plenty</u> of scope for improvement in the coming months.=
 <br><br>As I&#39;ve said several times in the last week, I&#39;m gobsmack=
ed that anyone, apart from G6ALB 3kms away, is able to hear me with the se=
t-up I have. The 500kHz WSPR beacon will run one more time overnight tonig=
ht=A0 then it will be off for 2-3 weeks.=A0 <br>
<br>My wife is wanting her dressing table back as the tiny ATU is sitting
on it and tuning is very sharp; every time she puts anything down I have
to check the antenna current is peaked :-))<br><br>
You know I&#39;m like a kid: I get <i>so</i> excited looking at the spots=
 and thinking about gradually making improvements and seeing my coverage=
 extend on 500kHz. <br><br>My wife just humours me!<br><br>73s<br>Roger G3=
XBM<br>
<br><br><div class=3D"gmail_quote">2009/9/19 James Moritz <span dir=3D"ltr=
">&lt;<a href=3D"mailto:james.moritz@btopenworld.com">james.moritz@btopenw=
orld.com</a>&gt;</span><br><blockquote class=3D"gmail_quote" style=3D"bord=
er-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-=
left: 1ex;">
Dear Roger, LF Group,<br>
<br>
It is interesting to make an estimate of what G3XBM&#39;s ERP might be...<=
br>
<br>
The noise level at M0BMU during relatively quiet daytime conditions I esti=
mate to be of the order of 3uV/m in the 2.5kHz WSPR reference bandwidth.=
 The reported SNR gets up to about -25dB, making the signal level from G3X=
BM about 0.18uV/m.<br>

<br>
ERP =3D (Ed)^2 / 49; with E =3D 0.18 x 10e-6, d =3D 69000m , ERP is about=
 3uW with only &quot;geometric spreading&quot; propagation losses. But the=
re is some additional reduction in field strength due to ground wave propa=
gation losses, perhaps 3dB with &quot;good&quot; ground, so the ERP would=
 then become about 6uW. Diffraction losses due to the curvature of the ear=
th are negligible at this distance.<br>

<br>
Obviously, this could be +/- several dB due to various uncertainties, but=
 should be of the right order of magnitude. Plenty of potential for improv=
ement then!<br>
<br>
Cheers, Jim Moritz<br>
73 de M0BMU <br>
<br>
</blockquote></div><br><br clear=3D"all"><br>-- <br>----------------------=
---------------------------------------<br><a href=3D"http://g3xbm-qrp.blo=
gspot.com/">http://g3xbm-qrp.blogspot.com/</a><br><a href=3D"http://www.g3=
xbm.co.uk">http://www.g3xbm.co.uk</a><br>
G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088<br>

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