Return-Path: Received: from mtain-db10.r1000.mx.aol.com (mtain-db10.r1000.mx.aol.com [172.29.64.94]) by air-di01.mail.aol.com (v126.13) with ESMTP id MAILINDI013-eab84b70778aac; Mon, 08 Feb 2010 15:43:54 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-db10.r1000.mx.aol.com (Internet Inbound) with ESMTP id 0DC2F38017A44; Mon, 8 Feb 2010 15:13:16 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NeZwk-0001Bn-D0 for rs_out_1@blacksheep.org; Mon, 08 Feb 2010 20:11:02 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NeZwj-0001Be-SB for rsgb_lf_group@blacksheep.org; Mon, 08 Feb 2010 20:11:01 +0000 Received: from smtp826.mail.ukl.yahoo.com ([217.12.13.123]) by relay1.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1NeZwh-0003ud-8f for rsgb_lf_group@blacksheep.org; Mon, 08 Feb 2010 20:11:01 +0000 Received: (qmail 46211 invoked from network); 8 Feb 2010 20:10:53 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=btinternet.com; h=Received:X-Yahoo-SMTP:X-YMail-OSG:X-Yahoo-Newman-Property:From:To:Subject:Date:Message-ID:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE:In-Reply-To:Thread-Index:Importance; b=ko0fKNWiDITXDcRizLU02tkw3Twy/QHGNedoxCVwcn6xCn5/M5vaE1vvuPofvfYjck9k0xjQHRT6EtaXbMpJSfn9sg/yw6osaUSDc30sr7z8Bh6qoqznPRBQ65LCcWE1kxvOKp669ORmZzJWA75jHYHW4OBGrEv0o7uSF3DkCf8= ; Received: from unknown (HELO Inspiron) (hudsonville@86.144.17.24 with login) by smtp826.mail.ukl.yahoo.com with SMTP; 8 Feb 2010 20:10:52 -0000 X-Yahoo-SMTP: T9P8HheswBCXVWXq3ajpBY99bVSvRxQZ2abOUyeQ53_fqQzzpx0V X-YMail-OSG: kTcIamcVM1kkLqSLQsinMCM_Z5YX4YC1NKSr3La9a7AMw08OOAZlkZP_RQ7.mylNOYcwinU2CBdK2jNN2idJrThMBXMPoxKVQPrWnqaWBK2h49ycKKa7fKm0R434_LfSxOcxZaNAq7bQmrg4o5aTAIlskRq4g5BUnVYq4b.BkSkPQ.lI7CB8OhrNJe.2cMB6P3HuViuEbicAwmZ2gYHHVJTamgcCOelUtaynV8DpKLOJ5w3ktXVgE3tj.tIY5v9dNU8.daOCgkMP X-Yahoo-Newman-Property: ymail-3 From: "Lee Hudson" To: Date: Mon, 8 Feb 2010 20:10:52 -0000 Message-ID: MIME-Version: 1.0 X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6838 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 In-Reply-To: Thread-Index: AcqoIoBlrM3slppiQB+z3Fen/bAmoQA0Co+g Importance: Normal DomainKey-Status: good (testing) X-Spam-Score: 3.4 (+++) X-Spam-Report: autolearn=disabled,FORGED_MUA_OUTLOOK=3.36,HTML_MESSAGE=0.001 Subject: LF: RE: WSPR S/N Tests Content-Type: multipart/alternative; boundary="----=_NextPart_000_0089_01CAA8FA.D0D43920" 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=FORGED_MUA_OUTLOOK,HTML_30_40, HTML_FONTCOLOR_BLUE,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: 3039ac1d405e4b70705c71b8 X-AOL-IP: 193.82.116.20 ------=_NextPart_000_0089_01CAA8FA.D0D43920 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable Hi Andy, Jim, LF Group, =20 I did a similar test back in January and had similar results using a= 20Hz bandwidth on WE2XGR/6 and managed 20dB or so improvement. The WSPR spectrogram showed nicely the ripples in the filter used, and appeared to be a limiting factor as to how far you could go. Also WSPR spent more time trying to recover something from these rippl= es, in one case nearly the full 2 mins. =20 Test was triggered also by too good to be true signal reports from som= e stations, as Andy has spotted. Interestingly these stations would fail to report other stations that= should clearly be readable given the S/N ratios reported. =20 With careful inspection of the reports it was sort of possible to get= a feel for what bandwidth was actually being monitored. But not conclusive en= ough to be sure. A transmitting station that drifted through the WSPR band= was very handy for highlighting this. Looking at the spread of S/N reports you would also find a sudden cut= off point way above -30dB norm were reports would not be given and this co= uld be an indicator of the gain achievable by over filtering that should tie= in with your findings. Rather than spend hours analysing logs, and contemplating how my stati= on could be improved further, it was much easier to discount these report= s all together as being unreliable and of no use. =20 73, Lee M0LMH. =20 -----Original Message----- From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Andy Talbot Sent: 07 February 2010 18:21 To: rsgb_lf_group@blacksheep.org Cc: jfell@tesco.net Subject: LF: WSPR S/N Tests To try to get to grips with the falsely high values of S/N reported= by some stations recently, I made a set of controlled measurements over a dire= ct link using a range of Rx bandwidths and input signal levels. =20 The results were dramatic. With receive bandwidths less than 300Hz,= the reported S/N increased considerably. It was only possible to use bandwidths in steps of 500Hz so 100,150,200 etc with the SDR-IQ but th= ese were more than enough to show the effect. =20 Full details can be found in www.g4jnt.com/WSPR_SNR_Test.pdf but the results can be summarised as : =20 ------------- Don't use a bandwidth below 300Hz unless you want artificially high SNR reports ----------------------- =20 300Hz or anything higher that allows the decoding software to see the= full noise band is OK. Andy www.g4jnt.com =20 No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.733 / Virus Database: 271.1.1/2674 - Release Date: 02/07/= 10 19:35:00 ------=_NextPart_000_0089_01CAA8FA.D0D43920 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable Message
Hi=20 Andy, Jim, LF Group,
 
I did=20 a similar test back in January and had similar results using a 20Hz ba= ndwidth on=20 WE2XGR/6 and managed 20dB or so improvement.
The=20 WSPR spectrogram showed nicely the ripples in the filter used, and app= eared to=20 be a limiting factor as to how far you could go.
Also=20 WSPR spent more time trying to recover something from these ripples,= in one case=20 nearly the full 2 mins.
 
Test=20 was triggered also by too good to be true signal reports from some sta= tions, as=20 Andy has spotted.
Interestingly these stations would fail to report other= stations that=20 should clearly be readable given the S/N ratios reported.
 
With=20 careful inspection of the reports it was sort of possible to get a fee= l for what=20 bandwidth was actually being monitored. But not conclusive eno= ugh to be sure. A=20 transmitting station that drifted through the WSPR band was very handy= for=20 highlighting this.
Looking at the spread of S/N reports you would also fin= d a sudden cut=20 off point way above -30dB norm were reports would not be given and thi= s could be=20 an indicator of the gain achievable by over filtering that should tie= in with=20 your findings.
Rather=20 than spend hours analysing logs, and contemplating how my station coul= d be=20 improved further, it was much easier to discount these reports all tog= ether as=20 being unreliable and of no use.
 
73,
Lee=20 M0LMH.
 
-----Original Message-----
Fro= m:=20 owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@black= sheep.org]=20 On Behalf Of Andy Talbot
Sent: 07 February 2010=20 18:21
To: rsgb_lf_group@blacksheep.org
Cc:=20 jfell@tesco.net
Subject: LF: WSPR S/N Tests

=
To try to get to grips with the falsely high values of  S/= N reported=20 by some stations recently, I made a set of controlled measurements= over a=20 direct link using a range of Rx bandwidths and input signal levels.<= /DIV>
 
The results were dramatic.  With receive bandwidths= less than=20 300Hz, the reported S/N increased considerably.   It was= only=20 possible to use bandwidths in steps of 500Hz so 100,150,200 etc with= the=20 SDR-IQ but these were more than enough to show the effect.
 
Full details can be found in www.g4jnt.com/WSPR_SNR_Test.pdf =20 but the results can be summarised as :
 
-------------   Don't use a bandwidth below 300Hz unl= ess you=20 want artificially high SNR reports  =20  -----------------------
 
300Hz or anything higher that allows the decoding software to= see the=20 full noise band is OK.

No virus found in this incoming messa= ge.
Checked=20 by AVG - www.avg.com
Version: 9.0.733 / Virus Database: 271.1.1/2= 674 -=20 Release Date: 02/07/10 19:35:00

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