Return-Path: Received: from mtain-db11.r1000.mx.aol.com (mtain-db11.r1000.mx.aol.com [172.29.64.95]) by air-df03.mail.aol.com (v126.13) with ESMTP id MAILINDF032-5eeb4b4afbf911; Mon, 11 Jan 2010 05:22:49 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-db11.r1000.mx.aol.com (Internet Inbound) with ESMTP id EAD5A380000A7; Mon, 11 Jan 2010 05:22:38 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NUHKd-0000Xi-Ew for rs_out_1@blacksheep.org; Mon, 11 Jan 2010 10:17:07 +0000 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NUHKa-0000XZ-9k for rsgb_lf_group@blacksheep.org; Mon, 11 Jan 2010 10:17:05 +0000 Received: from out1.ip05ir2.opaltelecom.net ([62.24.128.241]) by relay3.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NUHKQ-0004ih-7M for rsgb_lf_group@blacksheep.org; Mon, 11 Jan 2010 10:16:56 +0000 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AsQEADmJSktZ8oc7/2dsb2JhbACNVQbHPYQvBA X-IronPort-AV: E=Sophos;i="4.49,255,1262563200"; d="scan'208,217";a="282320024" Received: from unknown (HELO your91hoehfy9g) ([89.242.135.59]) by out1.ip05ir2.opaltelecom.net with SMTP; 11 Jan 2010 10:16:47 +0000 Message-ID: <002701ca92a7$306cf080$0301a8c0@your91hoehfy9g> From: "mal hamilton" To: References: <000e01ca9223$6d16ec90$0517aac0@desktop> <9afca2641001101102r6252b153lf6d911ee622589e5@mail.gmail.com> <004101ca922b$214cf0e0$0401a8c0@xphd97xgq27nyf> <9afca2641001101153u288ebc3dh81ba03efc09b650@mail.gmail.com> <38A51B74B884D74083D7950AD0DD85E82A1A8E@File-Server-HST.hst.e-technik.tu-darmstadt.de> Date: Mon, 11 Jan 2010 10:16:49 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Spam-Score: 1.5 (+) X-Spam-Report: autolearn=disabled,AMATEUR_PORN=1.473,HTML_MESSAGE=0.001 Subject: Re: LF: WSPR, QRSS, CW... Content-Type: multipart/alternative; boundary="----=_NextPart_000_0024_01CA92A7.3001AB90" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: **** X-Spam-Status: No, hits=4.9 required=5.0 tests=AMATEUR_PORN,CELL_PHONE_BOOST, HTML_20_30,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: 3039ac1d405f4b4afbee5f2f X-AOL-IP: 193.82.116.20 ------=_NextPart_000_0024_01CA92A7.3001AB90 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Andy At least my discussion and observations about radio operators versus= appliance operators has provoked some further analysis and comments= by yourself and others. The beauty of CW and variations of the mode handled by a competent ope= rator is simplicity, just a basic TX carrier keyed on/off, basic RX ju= st a regen TRF device and a good pair of Ears. The appliance operator= needs computers, appropriate software and keyboard skills to try and= achieve a similar result, and often fails. There is no substitute for a skilled radio operator to pass essential= short messages, which applies to most radio amateur communications,= however if one requires large volume exchanges of messages or data th= en some mechanical or electronic support is useful as in commercial ra= dio. The machine operator/appliance operator is useful in this case,= why pay a skilled radio operaror.=20 The discerning LF/MF interesred person should start by learning the mo= rse code, build a simple TX/RX, get as much wire into the air as possi= ble(antenna) fire up and surprise yourself with the results pounding= the KEY. G3KEV =20 =20 ----- Original Message -----=20 From: Andy Talbot=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Sunday, January 10, 2010 10:49 PM Subject: Re: LF: WSPR, QRSS, CW... There is an absolute limit to signalling efficiency, determined by= Shannon in 1948 of -1.64dB S/N (normalised bandwidth) WSPR/WSJT are= within about 3 - 4dB of the limit, so we'll only ever get this improv= ement to play with. Of course, we can go narrower and narrower and= longer and longer, but there comes a point where the ionospheric path= just won't support the signalling any more And that's it. All that's left is more EIRP, directional Rx antenna= s, noise cancellation and... For the signal in noise story, see if you can find a copies of : "Communication in the Presence of Noise", CE Shannon, Proc. IRE= (now IEEE) January 1949 =20 which is the seminal paper that sets the -1.64dB S/N limit=20 =20 --- and --- "Poisson, Shannon and the Radio Amateur" , JP Costas, Proc IRE, Dec= ember 1959 which spells it all out in a delightfully readable way Most human modes, morse and QRSS, and Hell all come out at a roughly= similar normalised S/N, and machine modes, at the moment roughly 4 -= 6dB better than the best humans ops. As shown, coding could further= improve things by another couple of dB. So who's going to be the first with MFSK Turbo coding on LF. ? That's real Amateur Radio as far as I'm concerned. Not faffing abou= t struggling to dig tones out of noise or looking for lines of differe= nt coloured dots=20 Andy www.g4jnt.com What will happen if in 2 years the next software will be available= with even much better error correction and so on? What, if this softw= are is so good that a QSO to VK will be possible? ------=_NextPart_000_0024_01CA92A7.3001AB90 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Andy
At least my discussion and observatio= ns about radio=20 operators versus appliance operators has provoked some further analysi= s and=20 comments by yourself and others.
The beauty of CW and variations of th= e=20 mode handled by a competent operator is simplicity, jus= t a basic=20 TX carrier keyed on/off, basic RX just a regen TRF device an= d a good=20 pair of Ears. The appliance operator needs computers, appropriate soft= ware and=20 keyboard skills to try and achieve a similar result, and often=20 fails.
There is no substitute for a skilled= radio operator=20 to pass essential short messages, which applies to=20 most radio amateur communications, however if one= requires=20 large volume exchanges of messages or data then some mechanical= or=20 electronic support is useful as in commercial radio. The machine=20 operator/appliance operator is useful in this case, why pay a skilled= radio=20 operaror.
The discerning LF/MF interesred perso= n should start=20 by learning the morse code, build a simple TX/RX, get as much wire int= o the air=20 as possible(antenna) fire up and surprise yourself with the resul= ts=20 pounding the KEY.
G3KEV
 
 
----- Original Message -----
From:=20 Andy Talbot
Sent: Sunday, January 10, 201= 0 10:49=20 PM
Subject: Re: LF: WSPR, QRSS,= CW...

There is an absolute limit to signalling efficiency, determined= by=20 Shannon in 1948 of -1.64dB S/N (normalised bandwidth)   WS= PR/WSJT=20 are within about 3 - 4dB of the limit, so we'll only ever get= this=20 improvement to play with.   Of course, we can go narrower= and=20 narrower and longer and longer, but there comes a point where= the=20 ionospheric path just won't support the signalling any more
 
And that's it.  All that's left is more EIRP, directi= onal Rx=20 antennas, noise cancellation and...
 
For the signal in noise story, see if you can find a copies of= :
 
"Communication in the Presence of Noise",  CE Shannon,&nbs= p; Proc.=20  IRE  (now IEEE)   January 1949 
which is the seminal paper that sets the  -1.64dB S/N= limit=20
  
--- and ---
 
"Poisson, Shannon and the Radio Amateur" ,  JP Costas, Pro= c IRE,=20 December 1959   which spells it all out in a delightfully= readable=20 way
 
Most human modes, morse and QRSS, and Hell all come out at a ro= ughly=20 similar normalised S/N, and machine modes, at the moment roughly 4= - 6dB=20 better than the best humans ops.   As shown,=20 coding could further improve things by another couple of= dB.
 
So who's going to be the first with MFSK Turbo coding on LF.&nb= sp;=20 ?
That's real Amateur Radio as far as I'm concer= ned. =20 Not faffing about struggling to dig tones out of noise or looking fo= r lines of=20 different coloured dots
What=20 will happen if in 2 years the next software will be available with= even much=20 better error correction and so on? What, if this software is so go= od that a=20 QSO to VK will be=20 possible?

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