Return-Path: Received: from rly-md07.mx.aol.com (rly-md07.mail.aol.com [172.20.29.145]) by air-md09.mail.aol.com (v125.7) with ESMTP id MAILINMD093-9114ae4b86f283; Sun, 25 Oct 2009 16:43:49 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-md07.mx.aol.com (v125.7) with ESMTP id MAILRELAYINMD071-9114ae4b86f283; Sun, 25 Oct 2009 16:43:29 -0400 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1N29vA-0000ax-Pw for rs_out_1@blacksheep.org; Sun, 25 Oct 2009 20:42:36 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1N29vA-0000ao-5z for rsgb_lf_group@blacksheep.org; Sun, 25 Oct 2009 20:42:36 +0000 Received: from mail-bw0-f221.google.com ([209.85.218.221]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1N29tT-0003jU-K5 for rsgb_lf_group@blacksheep.org; Sun, 25 Oct 2009 20:40:53 +0000 Received: by bwz21 with SMTP id 21so1758161bwz.4 for ; Sun, 25 Oct 2009 13:42:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:content-type; bh=lkEKG/n6z5XgDe648LNZKdfk6tge6tQkwwUeJXv+IRM=; b=lPH4BU/ITGC3D6IC3EiJ3tg8CRYQuE0LgF1a2pOI2DHXQz6gcRlTtyGy4OpV7HAgvi 2szWRJ9Rv9TZvPNIg1g1YZ5+VYYT/W5C+z9tsIvFj8RIED01lqsMcTz6yVE965oAkg0q uf28G6rGpsa6w/kC6iBt5boXwabUU9rJVfTwo= DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=RzdOn0sunSB16MunqM/txRMgHzauM79ogYsGdgPGBRMo/fAGpFQ2pTNjzBqfVKwhso ltwxSfVFNWQ/yavrG+SXoGWPv4FamN3nMHkdMDV8EHtvPEV1q0PnBLjX2hG9CKIZPnyK dcP8KM89y2EoLe7K1gz7TQFKhZHdVD0X0r5Zg= MIME-Version: 1.0 Received: by 10.239.183.32 with SMTP id s32mr1285008hbg.170.1256503333949; Sun, 25 Oct 2009 13:42:13 -0700 (PDT) In-Reply-To: <14E9228C113E44A6A66C5DEF8A144F28@AGB> References: <9afca2640910240855l4ad81f57sc7247c1c78a1365f@mail.gmail.com> <14E9228C113E44A6A66C5DEF8A144F28@AGB> Date: Sun, 25 Oct 2009 20:42:13 +0000 Message-ID: From: Andy Talbot To: rsgb_lf_group@blacksheep.org X-Karma: unknown: DomainKey-Status: good (testing) X-Spam-Score: 0.1 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,HTML_TAG_EXIST_TBODY=0.126 Subject: Re: LF: 500kHz 1mW WSPR beaconing Content-Type: multipart/alternative; boundary=001485f792b6e110f40476c87afc X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.9 required=5.0 tests=HTML_30_40,HTML_MESSAGE, HTML_TAG_EXISTS_TBODY 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-IP: 193.82.116.20 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-m203.1 ; domain : googlemail.com DKIM : pass X-Mailer: Unknown (No Version) --001485f792b6e110f40476c87afc Content-Type: text/plain; charset=ISO-8859-1 --- There is no 'chance' involved. The strong source coding employed in all the WSJT modes to get the number of bits to be encoded down to an absolute minimum, before proper error correction is added, removes all wasted redundancy in the original callsign format. This has the result that most *truly random* bit patterns will therefore generate a valid looking callsign. Its an artefact of efficient coding. That this only happens occasionally is due to the strong properly constructed error correction that is subsequently added. * BUT* As the callsign is not encoded in the most efficient way it could possibly be (which would be a codebook of all the radio-ams in the world = 1 million perhaps with a 20 bit reference number) we identify an invalid callsign by experience, and by correlating with known propagation / locator facts. Information theory is a wonderful study - and being able to be put into practice more easily with cheap processing power than it ever was before. I'll be covering this, amongst other aspects of weak signalling, at the Martlesham Microwave Roundtable. http://mmrt.homedns.org/start.html (talk entitled 6dB better than CW.) Andy www.g4jnt.com this email has been scanned for political correctness by the nanny state 2009/10/24 Graham > Roger > > This happened .. > > G ,, > > Timestamp Call MHz SNR Drift Grid Pwr Reporter RGrid km az 2009-10-24 > 16:58 G3XBM 0.503917 -28 0 JO02dg 0.001 G0NBD IO83 261 > 302 > > *From:* Roger Lapthorn > *Sent:* Saturday, October 24, 2009 4:55 PM > *To:* rsgb_lf_group@blacksheep.org > *Subject:* LF: 500kHz 1mW WSPR beaconing > > This will be active periodically over the weekend. It would be nice to get > a few new reporters spotting me. > > 73s > Roger G3XBM > > -- > ------------------------------------------------------------- > http://g3xbm-qrp.blogspot.com/ > http://www.g3xbm.co.uk > G3XBM GQRP 1678 ISWL G11088 > > ------------------------------ > > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 8.5.423 / Virus Database: 270.14.29/2455 - Release Date: 10/24/09 > 06:43:00 > > > --001485f792b6e110f40476c87afc Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
---
There is no 'chance' involved.=A0 The strong source coding em= ployed in all the WSJT modes to get the=A0number of bits to be encoded dow= n to an absolute minimum, before proper error correction is added,=A0remov= es all wasted redundancy in the original callsign format.=A0=A0 This has= the result that most truly random bit patterns will therefore gene= rate a valid looking callsign.=A0 Its an artefact of efficient coding.
=A0
That this only happens occasionally is due to the strong properly con= structed error correction that is subsequently added.=A0=A0
=A0
=A0BUT =A0=A0 As the callsign is not encoded in the= most efficient way it could possibly be (which would be a codebook of all= the radio-ams in the world=A0 =3D 1 million perhaps=A0with a 20 bit refer= ence number) we identify an invalid callsign by experience, and by correla= ting with known propagation / locator facts.=A0=A0
=A0
Information theory is a wonderful study - and being able to be put in= to practice more easily with cheap processing power than it ever was befor= e.=A0=A0 I'll be covering this, amongst other aspects of weak signalli= ng, at the Martlesham Microwave Roundtable.=A0 http://mmrt.homedns.org/start.html=A0=A0 (talk ent= itled 6dB better than CW.)

Andy
www.g4jnt.= com

this email has been scanned for political correctness by th= e nanny state


2009/10/24 Graham <g8fzk@g8fzk.fsnet.co.uk>=
Roger
=A0
This happened ..
=A0
G ,,
=A0
Timestamp Call MHz SNR Drift Grid Pwr Reporter RGrid km az
=A02009-10-24 16:58=A0 =A0G3XBM=A0 =A00.503917=A0 =A0-28=A0 =A00=A0 =A0JO02dg=A0 =A00.001=A0 =A0G0NBD=A0 =A0IO83=A0 =A0261=A0 =A0302=A0

Sent: Saturday, October 24, 2009 4:55 PM
Subject: LF: 500kHz 1mW WSPR beaconing

This will be active periodically over the weekend. It would= be nice to get a few new reporters spotting me.

73s
Roger G3XBM=

--
---------------------------------------------= ----------------
http://g3xbm-= qrp.blogspot.com/
http://www.g3xbm.co.uk
G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL= G11088


No virus found in this incoming message.
Checked by AVG - www.avg.com
Versio= n: 8.5.423 / Virus Database: 270.14.29/2455 - Release Date: 10/24/09 06:43= :00



--001485f792b6e110f40476c87afc--