Return-Path: Received: from mtain-mc09.r1000.mx.aol.com (mtain-mc09.r1000.mx.aol.com [172.29.96.81]) by air-db09.mail.aol.com (v129.4) with ESMTP id MAILINDB094-869d4c7e8ff02ed; Wed, 01 Sep 2010 13:40:00 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-mc09.r1000.mx.aol.com (Internet Inbound) with ESMTP id 7A65C380000B7; Wed, 1 Sep 2010 13:39:58 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OqrH6-00047n-Mq for rs_out_1@blacksheep.org; Wed, 01 Sep 2010 18:39:04 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OqrH6-00047e-36 for rsgb_lf_group@blacksheep.org; Wed, 01 Sep 2010 18:39:04 +0100 Received: from out1.ip01ir2.opaltelecom.net ([62.24.128.237]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OqrH0-0001z3-KN for rsgb_lf_group@blacksheep.org; Wed, 01 Sep 2010 18:39:04 +0100 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Av0EAFcsfkxcEY6J/2dsb2JhbACPXQORAHG/X4U5BIFXi0s X-IronPort-AV: E=Sophos;i="4.56,305,1280703600"; d="scan'208,217";a="322701789" Received: from unknown (HELO xphd97xgq27nyf) ([92.17.142.137]) by out1.ip01ir2.opaltelecom.net with SMTP; 01 Sep 2010 18:38:52 +0100 Message-ID: <003b01cb49fc$89767860$0401a8c0@xphd97xgq27nyf> From: "mal hamilton" To: References: <000a01cb493d$fb8f3410$0401a8c0@xphd97xgq27nyf><4C7E2046.536.2C4F91@v.d.heide.on-line.de><002501cb49f0$acabccb0$0401a8c0@xphd97xgq27nyf> Date: Wed, 1 Sep 2010 18:38:49 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: VLF THOUGHT Content-Type: multipart/alternative; boundary="----=_NextPart_000_0038_01CB4A04.EB0D8ED0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.8 required=5.0 tests=HTML_30_40,HTML_MESSAGE autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false x-aol-global-disposition: G x-aol-sid: 3039ac1d60514c7e8fee6115 X-AOL-IP: 193.82.116.20 X-AOL-SPF: domain : blacksheep.org SPF : none ------=_NextPart_000_0038_01CB4A04.EB0D8ED0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Theoretically that is correct but the Man in a previous email said he= was able to hear the rock concert audio 20 Kilometres away and that= was scattered audio. He was able to hear the total audio spectrum and depending on the indi= vidual hearing spectrum could be 0 - 15 Kcs.=20 Perhaps the distance was even greater. You are saying Megawatts audio= would fizzle out a couple of Kilometres away, which is not true. I ha= ve heard public address system several miles away also I remember the= old sirens years ago when they were used for emergency alerts, these= could be heard tens of miles away maybe 20 - 30 miles and were not Me= gawatts. g3kev ----- Original Message -----=20 From: Warren Ziegler=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Wednesday, September 01, 2010 5:40 PM Subject: Re: LF: VLF THOUGHT Mal, You seem to be intent on ignoring the basic physics.=20 An 8.97Kcs audio tone is attenuated at 130dB/km.=20 You are proposing concentrating the sound in one direction, analogou= s to a directive antenna, still with say 10kW and an 'antenna' (actual= ly speaker directivity) gain of say 30dB you would start out with eff= ectively 10MW, but with 130dB/km you would be down to 1 microwatt at= a distance of 1km !!!=20 Ten MEGAWATTS becomes 1 MICROWATT after 1km at 8.97 kHz!!! Case closed! On Wed, Sep 1, 2010 at 12:13 PM, mal hamilton wrote: With all the energy concentrated into a single tone on 8.97 Kcs = it could well travel a considerable distance with a few Kilowatts of= audio beamed in an arranged direction, especially along a valley. I am surprised that the high voltage 50 Hz electricity overhead di= stribution network is not heard over great distances by ear. g3kev ----- Original Message -----=20 From: Warren Ziegler=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Wednesday, September 01, 2010 3:31 PM Subject: Re: LF: VLF THOUGHT Rik,=20 Krakatoa exploded with the equivalent force of 200 Megatons= of TNT, bigger than the largest Hydrogen bomb and 13,000 times the si= ze of the nuclear explosion that destroyed Hiroshima. That said, I believe that what was hear at a distance was sti= ll the low frequency rumble, 100Hz is attenuated at only 0.3dB/km whil= e 10kHz is attenuated over 150dB/km. Best to stick with EM waves as opposed to sound. -=20 73 Warren K2ORS WD2XGJ=20 WD2XSH/23 WE2XEB/2 WE2XGR/1 On Wed, Sep 1, 2010 at 3:58 AM, Rik Strobbe wrote: All, here some real "DX":The explosion of the Krakatoa (1883) was= heard in Perth (Australia), 3100 km away, and on the island of Rodri= gues, 5000 km away. 73, Rik ON7YD ________________________________________ Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@b= lacksheep.org] namens Klaus von der Heide [v.d.heide@on-line.de] Verzonden: woensdag 1 september 2010 9:43 Aan: rsgb_lf_group@blacksheep.org Onderwerp: Re: LF: VLF THOUGHT Hello All, two years ago someone disturbed my breakfast by a deeply hammering disco sound. So I took my car to search for the source. Surprisingly, the sound decreased to nearly zero when I drove some kilometers in that direction where the sound seem to come from. The Odyssey took 45 minutes. But finally I found the open-air disco 20 km from my home in a lonely wood. Indeed, the sound took nearly 60 seconds from there to my home. That's more than a thunder usually reaches. More than thousand square-kilometers where contaminated, including 23 protected nature resevats. Yes we can, but Mankind should not do everything what it can. 73! Klaus, DJ5HG - =20 --=20 73 Warren K2ORS WD2XGJ=20 WD2XSH/23 WE2XEB/2 WE2XGR/1 =20 ------=_NextPart_000_0038_01CB4A04.EB0D8ED0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Theoretically that is correct but the=  Man in a=20 previous email said he was able to hear the rock concert audio 20 Kilo= metres=20 away and that was scattered audio.
He was able to hear the total audio= spectrum and=20 depending on the individual hearing spectrum could be 0 - 15 Kcs.
Perhaps the distance was even greater= . You are=20 saying Megawatts audio would fizzle out a couple of Kilometres away,= which is=20 not true. I have heard public address system several miles away also= I remember=20 the old sirens years ago when they were used for emergency alerts, the= se could=20 be heard tens of miles away maybe 20 - 30 miles and were not=20 Megawatts.
 
 
g3kev
 
----- Original Message -----
From:=20 Warren= Ziegler=20
Sent: Wednesday, September 01= , 2010 5:40=20 PM
Subject: Re: LF: VLF THOUGHT<= /DIV>

Mal,

    You seem to be intent on ignoring the basic= =20 physics. 

An 8.97Kcs audio tone is attenuated at 130dB/km. 

You are proposing concentrating the sound in one direction, ana= logous to=20 a directive antenna, still with say 10kW and an 'antenna' (actually= speaker=20 directivity)  gain of say 30dB you would start out with effecti= vely 10MW,=20 but with 130dB/km you would be down to 1 microwatt at a distance of= 1km=20 !!! 

Ten MEGAWATTS becomes 1 MICROWATT after 1km at 8.97 kHz!!!

Case closed!



On Wed, Sep 1, 2010 at 12:13 PM, mal hamilt= on <g3kevmal@talktalk.net>=20 wrote:
With all the energy concentrated= into a single=20 tone on 8.97 Kcs  it could well travel a considerable di= stance=20 with a few Kilowatts of audio beamed in an arranged dire= ction,=20 especially along a valley.
I am surprised that the high volt= age 50 Hz=20 electricity overhead distribution network is not heard over= great=20 distances by ear.
 
g3kev
 
----- Original Message -----
To: rsgb_lf_group@blacksheep.org
Sent: Wednesday, Septembe= r 01, 2010=20 3:31 PM
Subject: Re: LF: VLF THOU= GHT

Rik,=20

   Krakatoa exploded with the equivalent force of= 200=20 Megatons of TNT, bigger than the largest Hydrogen bomb and 13,00= 0 times=20 the size of the nuclear explosion that destroyed Hiroshima.
 
   That said, I believe that what was hear at a= distance=20 was still the low frequency rumble, 100Hz is attenuated at only= 0.3dB/km=20 while 10kHz is attenuated over 150dB/km.

Best to stick with EM waves as opposed to sound.

- 
73 Warren K2ORS
       =  =20       WD2XGJ 
       =  =20       WD2XSH/23
        &n= bsp;=20       WE2XEB/2
        &nb= sp;  =20     WE2XGR/1

On Wed, Sep 1, 2010 at 3:58 AM, Rik Str= obbe <Rik.Strobbe@fys.kuleuven.be><= /SPAN> wrote:
All,
=
here=20 some real "DX":The explosion of the Krakatoa (1883) was heard= in Perth=20  (Australia), 3100 km away, and on the island of Rodrigue= s, 5000 km=20 away.

73, Rik=20  ON7YD
________________________________________
Van= : owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Klaus= von=20 der Heide [v.d.heide@on-line.de]
Verzonden: woensdag 1=20 september 2010 9:43
Aan: rsgb_lf_group@blacks= heep.org
Onderwerp: Re: LF: VLF=20 THOUGHT

Hello All,


two years ago someone disturbed= my=20 breakfast by a deeply
hammering disco sound. So I took my= car to=20 search for
the source. Surprisingly, the sound decreased to= =20 nearly
zero when I drove some kilometers in that direction= =20 where
the sound seem to come from. The Odyssey took 45=20 minutes.
But finally I found the open-air disco 20 km from= my=20 home
in a lonely wood.

Indeed, the sound took nearly= 60=20 seconds from there to my
home. That's more than a thunder= usually=20 reaches.

More than thousand square-kilometers where=20 contaminated,
including 23 protected nature resevats.
Yes we=20 can, but Mankind should not do everything what it=20 can.


73!

Klaus,=20 DJ5HG



-
 



--
73 Warren K2ORS
 =        =20       WD2XGJ
         =  =20     WD2XSH/23
           =  =20   WE2XEB/2
             =  =20 WE2XGR/1

 
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