DomainKey-Signature: a=rsa-sha1; c=nofws;
        d=gmail.com; s=gamma;
        h=mime-version:in-reply-to:references:date:message-id:subject:from:to
         :content-type;
        b=VeUFBy1s39gWUFT94WuKmuRN2EO6nirfZ9qGl8cLSd4i3jnVHAKOu+FceAmQGIJTgU
         VMQ1YC/VOR5N0AVj48gH+jloDBkr8aA746apdkJzaPsEArz/+xM98GP0krQoUU6P7pHD
         6vjazdkvHRTyNH7dStsV4eHFN4VviZyrauhSY=
MIME-Version: 1.0
In-Reply-To: <BF4A524700075746A6467658DFC7102C5106464EEA@ICTS-S-EXC2-CA.luna.kuleuven.be>
References: <AANLkTinG-0mJJ3CDqFwxeLXfOJXFFfs42gjLYz8yX3rW@mail.gmail.com>
	 <38A51B74B884D74083D7950AD0DD85E82A1C00@File-Server-HST.hst.e-technik.tu-darmstadt.de>
	 <AANLkTilyd93InqPvp5qUVkonthTgtMaIVqVfH3zyen2B@mail.gmail.com>
	 <Pine.LNX.4.64.1005252313060.26690@paranoid.lipkowski.org>
	 <AANLkTimudswbmeqd9Ej52egRUOJ4RHIf5VtYiQ7_7d8T@mail.gmail.com>
	 <BF4A524700075746A6467658DFC7102C5106464EEA@ICTS-S-EXC2-CA.luna.kuleuven.be>
Date: Wed, 26 May 2010 09:43:44 +0100
Message-ID: <AANLkTimXcAWlXyxfo4gAThfv3maPkFNyKK6HYMNRxhk3@mail.gmail.com>
From: Roger Lapthorn <rogerlapthorn@gmail.com>
To: rsgb_lf_group@blacksheep.org
DomainKey-Status: good (testing) 
Subject: Re: LF: AW: 8.97kHz - Near field and radiated signals?
Content-Type: multipart/alternative; boundary=0015174ff3528e21d004877b45a9
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org


--0015174ff3528e21d004877b45a9
Content-Type: text/plain; charset=ISO-8859-1

Rick (et al),

I am confused by the near field attenuation rates quoted. Some quote *18dB
for doubling distance* which would mean an additional path loss of 56dB
going from 0.4km to 3km. This makes a lot of difference to what may or may
not be possible.

Which is the correct figure? Help!

73s
Roger G3XBM


On 26 May 2010 09:31, Rik Strobbe <Rik.Strobbe@fys.kuleuven.be> wrote:

>  Roger,
>
>
>
> the near fiels signal drops with the 3rd power of the distance.
>
> So 3km versus 0.4km = 422 times weaker = -26dB
>
> Going from regular CW to QRSS30 will give you a 24dB benefit, so there is a
> fair chance to be copied at 3km in this mode. Of course the signal needs to
> be very frequency stable, it has to be better than an free running
> oscillator.
>
> Moving up in frequency would also help.
>
> And if you can lay your hands on an old stereo amp it would provide an
> extra 10dB TX power.
>
>
>
> Even if your goal is regular CW over a 3km path, starting with QRSS will
> most likely give a visible signal at 3km and allow you to watch any
> progress.
>
>
>
> 73, Rik  ON7YD - OR7T
>
>
>
>>  - The best DX targets are quite modest: I would like to exceed 1km
>>
>>  initially with the TX power I currently have (around 4W). If I could
>> reach
>>  G6ALB in the next village 3kms away I would be delighted. If I got any
>>  further I would be both amazed and VERY happy!
>>
>


-- 
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
G3XBM    GQRP 1678      ISWL G11088

--0015174ff3528e21d004877b45a9
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

Rick (et al),<br><br>I am confused by the near field attenuation rates quo=
ted. Some quote <b>18dB for doubling distance</b> which would mean an addi=
tional path loss of 56dB going from 0.4km to 3km. This makes a lot of diff=
erence to what may or may not be possible.<br>
<br>Which is the correct figure? Help!<br><br>73s<br>Roger G3XBM <br><br><=
br><div class=3D"gmail_quote">On 26 May 2010 09:31, Rik Strobbe <span dir=
=3D"ltr">&lt;<a href=3D"mailto:Rik.Strobbe@fys.kuleuven.be">Rik.Strobbe@fy=
s.kuleuven.be</a>&gt;</span> wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin: 0pt 0pt 0pt 0.8ex; bord=
er-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">




<div>
<div style=3D"font-family: Tahoma; direction: ltr; color: rgb(0, 0, 0); fo=
nt-size: 13px;">
<p>Roger,</p>
<p><font face=3D"tahoma" size=3D"2"></font>=A0</p>
<p><font face=3D"tahoma" size=3D"2">the near fiels signal drops with the=
 3rd power of the distance.</font></p>
<p><font face=3D"tahoma" size=3D"2">So 3km versus 0.4km =3D 422 times weak=
er =3D -26dB</font></p>
<p><font face=3D"tahoma" size=3D"2">Going from regular CW to QRSS30 will=
 give you a 24dB benefit, so there is a fair chance to be copied at 3km in=
 this mode. Of course the signal needs to be very frequency stable, it has=
 to be better than an free running oscillator.</font></p>

<p><font face=3D"tahoma" size=3D"2">Moving up in frequency would also help=
.</font></p>
<p><font face=3D"tahoma" size=3D"2">And if you can lay your hands on an ol=
d stereo amp it would provide an extra 10dB TX power.</font></p>
<p>=A0</p>
<p><font face=3D"tahoma" size=3D"2">Even if your goal is regular CW over=
=A0a 3km path, starting with QRSS will most likely give a visible signal=
 at 3km and allow you to watch any progress.</font></p>
<p><font face=3D"tahoma" size=3D"2"></font>=A0</p>
<p><font face=3D"tahoma" size=3D"2">73, Rik=A0 ON7YD - OR7T</font></p><div=
 class=3D"im">
<p><font face=3D"tahoma" size=3D"2"></font>=A0</p>
<font face=3D"tahoma" size=3D"2">
<blockquote style=3D"border-left: 1px solid rgb(204, 204, 204); margin: 0p=
t 0pt 0pt 0.8ex; padding-left: 1ex;" class=3D"gmail_quote">
<p>=A0- The best DX targets are quite modest: I would like to exceed 1km=
 </p>
<div><br>
=A0initially with the TX power I currently have (around 4W). If I could re=
ach<br>
=A0G6ALB in the next village 3kms away I would be delighted. If I got any<=
br>
=A0further I would be both amazed and VERY happy!</div>
</blockquote>
</font></div></div>
</div>

</blockquote></div><br><br clear=3D"all"><br>-- <br><a href=3D"http://g3xb=
m-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.yo=
utube.com/user/g3xbm">http://www.youtube.com/user/g3xbm</a><br>
G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088<br>

--0015174ff3528e21d004877b45a9--