Return-Path: Received: from mtain-dc11.r1000.mx.aol.com (mtain-dc11.r1000.mx.aol.com [172.29.64.139]) by air-ma09.mail.aol.com (v129.4) with ESMTP id MAILINMA094-b53b4c2d96e928; Fri, 02 Jul 2010 03:36:09 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-dc11.r1000.mx.aol.com (Internet Inbound) with ESMTP id 90C23380000EF; Fri, 2 Jul 2010 03:36:07 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OUam3-0004H1-QG for rs_out_1@blacksheep.org; Fri, 02 Jul 2010 08:34:59 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OUam2-0004Fq-Oq for rsgb_lf_group@blacksheep.org; Fri, 02 Jul 2010 08:34:58 +0100 Received: from cavuit02.kulnet.kuleuven.be ([134.58.240.44]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OUam0-00029z-M2 for rsgb_lf_group@blacksheep.org; Fri, 02 Jul 2010 08:34:58 +0100 Received: from smtps02.kuleuven.be (smtpshost02.kulnet.kuleuven.be [134.58.240.75]) by cavuit02.kulnet.kuleuven.be (Postfix) with ESMTP id 24A7F51C002 for ; Fri, 2 Jul 2010 09:34:45 +0200 (CEST) Received: from ICTS-S-HUB-N1.luna.kuleuven.be (icts-s-hub-n1.luna.kuleuven.be [10.112.9.11]) by smtps02.kuleuven.be (Postfix) with ESMTP id 28F88F3862 for ; Fri, 2 Jul 2010 09:34:45 +0200 (CEST) Received: from ICTS-S-EXC2-CA.luna.kuleuven.be ([10.112.11.13]) by ICTS-S-HUB-N1.luna.kuleuven.be ([10.112.9.11]) with mapi; Fri, 2 Jul 2010 09:34:45 +0200 X-Kuleuven: This mail passed the K.U.Leuven mailcluster From: Rik Strobbe To: "rsgb_lf_group@blacksheep.org" Date: Fri, 2 Jul 2010 09:34:45 +0200 Thread-Topic: LF: 137.500 kHz ROS MF-1 beacon Thread-Index: AcsZtPZZEaB8qOhpRZegMBAXzRiXpQAAwgDk Message-ID: References: <063F5E5A75EC43DEB446F850ED876141@AGB>, In-Reply-To: Accept-Language: nl-NL, nl-BE Content-Language: nl-BE X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: nl-NL, nl-BE MIME-Version: 1.0 X-KULeuven-Information: Katholieke Universiteit Leuven X-KULeuven-Scanned: Found to be clean X-KULeuven-Envelope-From: rik.strobbe@fys.kuleuven.be 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="_000_BF4A524700075746A6467658DFC7102C51094D0DF6ICTSSEXC2CAlu_" 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,TO_ADDRESS_EQ_REAL,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-sid: 3039ac1d408b4c2d96e746ac X-AOL-IP: 193.82.116.20 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --_000_BF4A524700075746A6467658DFC7102C51094D0DF6ICTSSEXC2CAlu_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Andy, I guess it is the same SNR issue that has been noticed with WSPR. As you mentioned SNR is calculated for SSB bandwidth. If some uses a narro= w filter the calculated SNR is too low. If I remember well one of our French friends used a very narrow filter for= 500kHz WSPR reception, resulting in solid copy at very low (calculated)= SNR levels. 73, Rik ON7YD - OR7T ________________________________ Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.or= g] namens Andy Talbot [andy.g4jnt@googlemail.com] Verzonden: vrijdag 2 juli 2010 9:01 Aan: rsgb_lf_group@blacksheep.org Onderwerp: Re: LF: 137.500 kHz ROS MF-1 beacon A thought. MF1 ROS is one symbol per second isn't it. If you can decode at -33dB (pr= esumably in the reference bandwidth of 2.5kHz) that's -1dB S/N in a symbo= l bandwidth. Which I'm not sure I can believe. FSK with good Feed Solo= mon, 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 restr= icted 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 ve= ry welcome. ERP about 50mW. 73 Gary - G4WGT - IO83QO --_000_BF4A524700075746A6467658DFC7102C51094D0DF6ICTSSEXC2CAlu_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Andy,
 
I guess it is the same SNR issue tha= t has been noticed with WSPR.
As you mentioned SNR is calculated= for SSB bandwidth. If some uses a narrow filter the calculated SNR is too= low.
If I remember well one of our French= friends used a very narrow filter for 500kHz WSPR reception, resulting in= solid copy at very low (calculated) SNR levels.
 
73, Rik ON7YD - OR7T
 
Van: owner-rsgb_= lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Andy= Talbot [andy.g4jnt@googlemail.com]
Verzonden: vrijdag 2 juli 2010 9:01
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: Re: LF: 137.500 kHz ROS MF-1 beacon

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.&= nbsp;  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 bandwidt= h is restricted below a complete 2.5kHz's worth, and if impulsive noise is= present.  So could ROS be suffering some similar effect?
On 1 July 2010 23:47, Graham = <g8fzk@g8fzk.fsnet.co.uk= > wrote:
 
Gary,
 
Just a  couple of db's &nbs= p; short  of a  decode  via the  web , -36 is going so= me though
 

RX1:

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

G ..

 

Sent: Thursday, July 01, 2010 6:35 PM
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 at= tempts very welcome.

ERP about 50mW.

73

Gary - G4WGT - IO83QO



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