From: Rik Strobbe <Rik.Strobbe@fys.kuleuven.be>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
Date: Sat, 29 May 2010 11:21:36 +0200
Thread-Topic: BY EAR
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Subject: LF: RE: BY EAR
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Acoustic signals can be heard over large distances if conditions are right=
.
I live at about 5km north-east from the place where the famous "Rock Werch=
ter" festival takes place, one of the largest rock festivals in Europe (ht=
tp://www.rockwerchter.be/en/home/).
Their sound system is many 10kW. If the the wind comes from south-west I=
 can understand every word said throught the microphones. With other wind=
 directions I only hear the low tones.
Most of the time I find ths very annoying, except for that one time I coul=
d hear a full Bruce Springsteen concert as if I were on the concert.
My grandmother told me that in 1940 they could hear the bombing of Antwerp=
 harbour near their home, about 70km from Antwerp, but only at the banks=
 of the channel that goes in a almost staight line to Antwerp. I guess the=
 channel acted as some kind of wave guide.

But all this has nothing to do with electromagnetic communication at very=
 low frequencies.
This is experimenting and fun. Finding out how far one gets with just few=
 mW or less ERP. Testing different types of antennas.

73, Rik  ON7YD
________________________________
Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.or=
g] namens mal hamilton [g3kevmal@talktalk.net]
Verzonden: zaterdag 29 mei 2010 10:06
Aan: rsgb
Onderwerp: LF: BY EAR

As observed by others, I have heard car audio music several hundred metres=
 away. Out in an open field I think it would be possible to hear a 1Kw aud=
io system by ear a couple of miles away, and maybe further downwind. Dream=
ers would need to be aiming for several miles distance minimum and prefera=
bly hundreds of miles using radio.
mal/g3kev

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<div>Acoustic signals can be heard over large distances if conditions are=
 right.</div>
<div><font size=3D"2" face=3D"tahoma">I&nbsp;live at about 5km north-east=
 from the place where the famous &quot;Rock Werchter&quot; festival takes=
 place, one of the largest rock festivals in Europe (<a href=3D"http://www=
.rockwerchter.be/en/home/">http://www.rockwerchter.be/en/home/</a>).
</font></div>
<div><font size=3D"2" face=3D"tahoma">Their&nbsp;sound system is many 10kW=
.&nbsp;If the the wind comes from south-west I can understand every word=
 said throught the microphones. With other wind directions I only hear the=
 low tones.</font></div>
<div><font size=3D"2" face=3D"tahoma">Most of the time I find ths very ann=
oying, except for that one time I could hear a full Bruce Springsteen conc=
ert as if I were on the concert.</font></div>
<div><font size=3D"2" face=3D"tahoma">My grandmother told me that in 1940=
 they could hear the bombing of Antwerp harbour&nbsp;near their home, abou=
t 70km from Antwerp, but only at the banks of the channel that goes in a=
 almost staight line to Antwerp. I guess the channel
 acted as some kind of wave guide.</font></div>
<div><font size=3D"2" face=3D"tahoma"></font>&nbsp;</div>
<div><font size=3D"2" face=3D"tahoma">But all this has nothing to do with=
 electromagnetic communication at very low frequencies.</font></div>
<div><font size=3D"2" face=3D"tahoma">This is experimenting and fun. Findi=
ng out how far one gets with just few mW or less ERP. Testing different ty=
pes of antennas.</font></div>
<div><font size=3D"2" face=3D"tahoma"></font>&nbsp;</div>
<div><font size=3D"2" face=3D"tahoma">73, Rik&nbsp; ON7YD</font></div>
<div>
<hr tabindex=3D"-1">
</div>
<div><font color=3D"#000000" size=3D"2" face=3D"Tahoma"><b>Van:</b> owner-=
rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens=
 mal hamilton [g3kevmal@talktalk.net]<br>
<b>Verzonden:</b> zaterdag 29 mei 2010 10:06<br>
<b>Aan:</b> rsgb<br>
<b>Onderwerp:</b> LF: BY EAR<br>
</font><br>
</div>
<div></div>
<div>
<div><font size=3D"2" face=3D"Arial">As observed by others, I have heard=
 car audio music several hundred metres away. Out in an open field I think=
 it would be possible to hear a 1Kw audio system by ear a couple of miles=
 away, and maybe further downwind. Dreamers
 would need to be aiming for several miles distance minimum and preferably=
 hundreds of miles using radio.</font></div>
<div><font size=3D"2" face=3D"Arial">mal/g3kev</font></div>
<div>&nbsp;</div>
</div>
</div>
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