Return-Path: Received: from mtain-db12.r1000.mx.aol.com (mtain-db12.r1000.mx.aol.com [172.29.64.96]) by air-da08.mail.aol.com (v129.4) with ESMTP id MAILINDA084-86924c2d8f4f31b; Fri, 02 Jul 2010 03:03:43 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-db12.r1000.mx.aol.com (Internet Inbound) with ESMTP id 10F00380000AB; Fri, 2 Jul 2010 03:03:41 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OUaG6-0000kF-TZ for rs_out_1@blacksheep.org; Fri, 02 Jul 2010 08:01:58 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OUaG6-0000k6-9D for rsgb_lf_group@blacksheep.org; Fri, 02 Jul 2010 08:01:58 +0100 Received: from mail-bw0-f43.google.com ([209.85.214.43]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OUaG5-0001kR-2N for rsgb_lf_group@blacksheep.org; Fri, 02 Jul 2010 08:01:58 +0100 Received: by bwz13 with SMTP id 13so1626893bwz.16 for ; Fri, 02 Jul 2010 00:01:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=vqKuYCrCJyCDwGXc4OJ+aXBZsOSS26F6a0Zwp6bruUI=; b=mGtQgsv2fJYXWkcW8pUX+5bILy5TCCZ2UFvlGa7VxuGokDiXWlv59azGdJTK7UYxiX DRohYGJPJ4yR+ELJX7QHTbmckCcPcbOL/M+i/XDnVUAlNYiQFKL9545CRH2U2L/9kGl1 SkBtlL6Kjd21tKsgbvydXnANFZXtQSVzFxOdU= 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=aNOf8vAU9D+lzzdwYNaE8fJCD2jexzLMd3jRdP1/A1RGbx6gQj6TK0iOrcXsQ5r9QX N7B/JCvRJQn/VA47zaRNw3m0cP4nk3aJrTRi8MqPbWRLwpnuw0UOQlZAfih4zrva0KHq 4kaSIUSV/hDIhMZ0CjE6MXmr7DgRbWvFBFUT8= MIME-Version: 1.0 Received: by 10.204.46.205 with SMTP id k13mr227234bkf.143.1278054115702; Fri, 02 Jul 2010 00:01:55 -0700 (PDT) Received: by 10.204.67.18 with HTTP; Fri, 2 Jul 2010 00:01:55 -0700 (PDT) In-Reply-To: <063F5E5A75EC43DEB446F850ED876141@AGB> References: <063F5E5A75EC43DEB446F850ED876141@AGB> Date: Fri, 2 Jul 2010 08:01:55 +0100 Message-ID: From: Andy Talbot To: rsgb_lf_group@blacksheep.org DomainKey-Status: good (testing) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: 137.500 kHz ROS MF-1 beacon Content-Type: multipart/alternative; boundary=0016e6dcd27791fa1d048a622957 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: ** X-Spam-Status: No, hits=2.5 required=5.0 tests=HTML_40_50,HTML_FONTCOLOR_RED, HTML_MESSAGE,WEIRD_PORT 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-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d289.2 ; domain : googlemail.com DKIM : pass x-aol-sid: 3039ac1d40604c2d8f4d1274 X-AOL-IP: 193.82.116.20 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --0016e6dcd27791fa1d048a622957 Content-Type: text/plain; charset=ISO-8859-1 A thought. MF1 ROS is one symbol per second isn't it. If you can decode at -33dB (presumably in the reference bandwidth of 2.5kHz) that's -1dB S/N in a symbol bandwidth. Which I'm not sure I can believe. FSK with good Feed Solomon, or whatever, FEC needs 2 - 3dB S/N. Is the S/N calculation being a bit optimistic? The calculation in WSJT / WSPR gives an artificially high S/N value if the input bandwidth is restricted below a complete 2.5kHz's worth, and if impulsive noise is present. So could ROS be suffering some similar effect? Andy www.g4jnt.com On 1 July 2010 23:47, Graham wrote: > > Gary, > > Just a couple of db's short of a decode via the web , -36 is going > some though > > http://websdr.ewi.utwente.nl:8901/ > > RX1: > 21:55 @ 13.8 Hz: *[:]V-KFY:32DM5#("")EM3H#/F[_ -36 dB > > G .. > > > *From:* Gary - G4WGT > *Sent:* Thursday, July 01, 2010 6:35 PM > *To:* LF Group (RSGB) > *Subject:* LF: 137.500 kHz ROS MF-1 beacon > > Hi LF, > > My ROS MF-1 beacon is transmitting now with 3 minute timer. > > Frequency is 137.500 kHz (dial 136.500 kHz USB), reports & QSO attempts > very welcome. > > ERP about 50mW. > > 73 > > Gary - G4WGT - IO83QO > > > --0016e6dcd27791fa1d048a622957 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
A thought.=A0
MF1 ROS is one symbol per second isn't it.=A0 If you can decode= at -33dB (presumably in the reference bandwidth of 2.5kHz)=A0 that's= -1dB S/N in a symbol bandwidth.=A0=A0 Which I'm not sure I can believ= e.=A0=A0 FSK with good Feed Solomon, or whatever, FEC =A0needs 2 - 3dB S/N= .
=A0
Is the S/N calculation being a bit optimistic?=A0 The calculation in= WSJT / WSPR gives an artificially high S/N value if the input bandwidth= is restricted below a complete 2.5kHz's worth, and if impulsive noise= is present.=A0 So could ROS be suffering some similar effect?
On 1 July 2010 23:47, Graham = <g8fzk@g8fzk.fsnet.co.uk= > wrote:
=A0
Gary,
=A0
Just a=A0 couple of db's=A0=A0 sh= ort=A0 of a=A0 decode=A0 via the=A0 web , -36 is going some though =
=A0
http://websdr.ewi.utwente.nl:8901/<= /div>

RX1:

21:55 @ 13.8 Hz: *[:]V-KFY= :32DM5#("")EM3H#/F[_ <CANCEL&g= t; -36 dB=20

G ..

=A0

Sent: Thursday, July 01, 2010 6:35 PM
Subject: LF: 137.500 kHz ROS MF-1 beacon

Hi LF,=20

My ROS MF-1 beacon is transmitting now with 3 minute timer.

Frequency is 137.500 kHz (dial 136.500 kHz USB), reports & QSO at= tempts very welcome.

ERP about 50mW.

73

Gary - G4WGT - IO83QO



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