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=FPzQVgxXxWF0qJaASjp89iQkeUfhPpv5XTjTFqwT2z32nZlFNZqQRBiUBI8d7Qjab0
         N4E3TVQaP+Dxwd/JcWqyO/D2fjhmcZYjit/FZi1X+E00F92nEinj2DIHhpOhfLbLJTW6
         1es+7jOxiRllMi24SAgWfAl5qhNGKL1fd5uRM=
MIME-Version: 1.0
In-Reply-To: <000a01cb493d$fb8f3410$0401a8c0@xphd97xgq27nyf>
References: <000a01cb493d$fb8f3410$0401a8c0@xphd97xgq27nyf>
Date: Tue, 31 Aug 2010 15:24:07 -0400
Message-ID: <AANLkTik=xsDkf+CckVAcFKfG8Q27VqS6iJUcKUzafbaP@mail.gmail.com>
From: Warren Ziegler <wd2xgj@gmail.com>
To: rsgb_lf_group@blacksheep.org
DomainKey-Status: good (testing) 
Subject: Re: LF: VLF THOUGHT
Content-Type: multipart/alternative; boundary=00151750ea8039da19048f2387a9
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org


--00151750ea8039da19048f2387a9
Content-Type: text/plain; charset=ISO-8859-1

Mal,
   An interesting thought but if you keep the signal above the normal
hearing range the attenuation is severe!
 At 9 kHz the attenuation of sound is 130 dB/km. At 20kHz the attenuation of
sound is over 500 dB/km !!!!

This is why distant thunder sounds like a low rumble, all the high frequency
components have been attenuated.

See:
http://resource.npl.co.uk/acoustics/techguides/absorption/
<http://www.csgnetwork.com/atmossndabsorbcalc.html>and
http://www.csgnetwork.com/atmossndabsorbcalc.html


-- 
73 Warren K2ORS
                WD2XGJ
                WD2XSH/23
                WE2XEB/2
                WE2XGR/1

<http://www.csgnetwork.com/atmossndabsorbcalc.html>

On Tue, Aug 31, 2010 at 2:54 PM, mal hamilton <g3kevmal@talktalk.net> wrote:

>  I see 15 Kilowatt audio amplifiers advertised, therefore there must be a
> speaker system, public address horns available for such amplifiers.
> If one of these speaker horns was directed line of sight towards the
> horizon or a mountain top and a suitable dish positioned at the receive end,
> it must be possibel to intercept such a signal at audio frequencies. eg
> Transmit a tone which could be keyed at 9 - 20 Kcs and see what distance
> could be covered.
> Keeping the signal just above the normal human audio range would
> avoid interference.
> or just TX a signal at say 5 Kcs and see how far it could be heard by ear
> with this sort of power, maybe further than the same signal transmitted by
> radio means, except one had an exceptionally large antenna
> Maybe a NOV is required for this experiment!!!!
> de g3kev
>
>
>
>
>

--00151750ea8039da19048f2387a9
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

Mal,<div>=A0=A0 An interesting thought but if you keep the signal above th=
e normal hearing range the attenuation is severe!<br>=A0At 9 kHz the atten=
uation of sound is 130 dB/km.=A0At 20kHz the attenuation of sound is over=
 500 dB/km !!!!</div>
<div><br></div><div>This is why distant thunder sounds like a low rumble,=
 all the high frequency components have been attenuated.</div><div><br>See=
:</div><div><a href=3D"http://resource.npl.co.uk/acoustics/techguides/abso=
rption/">http://resource.npl.co.uk/acoustics/techguides/absorption/</a></d=
iv>
<div><a href=3D"http://www.csgnetwork.com/atmossndabsorbcalc.html"></a>and=
=A0</div><div><a href=3D"http://www.csgnetwork.com/atmossndabsorbcalc.html=
">http://www.csgnetwork.com/atmossndabsorbcalc.html</a></div><div><br></di=
v><div>
<br>--=A0<br>73 Warren K2ORS<br>=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XGJ=A0<=
br>=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XSH/23<br>=A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 WE2XEB/2<br>=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XGR/1<br></div><div=
><br></div><div><a href=3D"http://www.csgnetwork.com/atmossndabsorbcalc.ht=
ml"></a><br>
<br><div class=3D"gmail_quote">On Tue, Aug 31, 2010 at 2:54 PM, mal hamilt=
on <span dir=3D"ltr">&lt;<a href=3D"mailto:g3kevmal@talktalk.net">g3kevmal=
@talktalk.net</a>&gt;</span> wrote:<br><blockquote class=3D"gmail_quote"=
 style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">






<div bgcolor=3D"#ffffff">
<div><font face=3D"Arial" size=3D"2">I see 15 Kilowatt audio amplifiers ad=
vertised,=20
therefore there must be a speaker system, public address horns available=
 for=20
such amplifiers. </font></div>
<div><font face=3D"Arial" size=3D"2">If one of these speaker horns was dir=
ected line of=20
sight towards the horizon or a mountain top and a suitable dish positioned=
 at=20
the receive end, it must be possibel to intercept such a signal at audio=
=20
frequencies. eg Transmit a tone which could be keyed=A0at 9=A0-=20
20=A0Kcs and see what distance could be covered.</font></div>
<div><font face=3D"Arial" size=3D"2">Keeping the signal just above the nor=
mal=A0human=20
audio range would avoid=A0interference.</font></div>
<div><font face=3D"Arial" size=3D"2">or just TX a signal at say 5 Kcs and=
=A0see how=20
far it could be heard=A0by ear with this sort of power, maybe further than=
=20
the same signal transmitted by radio means, except one had an exceptionall=
y=20
large antenna</font></div>
<div><font face=3D"Arial" size=3D"2">Maybe a NOV is required for this=20
experiment!!!!</font></div>
<div><font face=3D"Arial" size=3D"2">de g3kev</font></div>
<div>=A0</div>
<div><font face=3D"Arial" size=3D"2"></font>=A0</div>
<div><font face=3D"Arial" size=3D"2"></font>=A0</div>
<div><font face=3D"Arial" size=3D"2">=A0=A0</font></div></div>
</blockquote></div><br><br clear=3D"all"><br>=A0<br>
</div>

--00151750ea8039da19048f2387a9--