Return-Path: Received: from mtain-dk10.r1000.mx.aol.com (mtain-dk10.r1000.mx.aol.com [172.29.180.14]) by air-da04.mail.aol.com (v129.4) with ESMTP id MAILINDA043-863c4d239b6721c; Tue, 04 Jan 2011 17:12:55 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dk10.r1000.mx.aol.com (Internet Inbound) with ESMTP id DB930380000A5; Tue, 4 Jan 2011 17:12:53 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1PaF6e-0001Gb-7X for rs_out_1@blacksheep.org; Tue, 04 Jan 2011 22:11:52 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1PaF6d-0001GS-GZ for rsgb_lf_group@blacksheep.org; Tue, 04 Jan 2011 22:11:51 +0000 Received: from mail-iy0-f171.google.com ([209.85.210.171]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1PaF6a-0007dl-R5 for rsgb_lf_group@blacksheep.org; Tue, 04 Jan 2011 22:11:51 +0000 Received: by iyj21 with SMTP id 21so13761934iyj.16 for ; Tue, 04 Jan 2011 14:11:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=WOfokkNLyqMIY0aSNTBeFlHVKH6vjL3B5ZowiOan3BI=; b=AytVM01qIvBa51Wwo/E7JYjk+TtSgot6ny71c1qL+qLl2YuhtBtIQ6SikbkLoP9NQe vjIizuiS+iYuECigyyoNvFy5q+VYAkpK4Vk0nxzXERpA+sPyY+j8PVEDxaAj24JejrFW G2NVpue0BrP24fAaXMPmd18QgC6IV+GLot9Eg= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=RPT6oGRoC6vxV5XN9LdzojXz+0bq2VkT51KBSXTfTca5SNP5lgNVgcsBhUHuWzTcai 2umibOusKzbGVeJoxB6N+64JljPigRej1tdjpUPoQReEDogdk7WLsqFi6h+7LVz6Mxoq 5fTJo7gcmYnKUCkXZIxxMRAByD0bkVoU6l3EM= MIME-Version: 1.0 Received: by 10.231.207.73 with SMTP id fx9mr11602360ibb.137.1294179102331; Tue, 04 Jan 2011 14:11:42 -0800 (PST) Received: by 10.231.200.211 with HTTP; Tue, 4 Jan 2011 14:11:42 -0800 (PST) In-Reply-To: <4D23931B.50505@toya.net.pl> References: <4D23931B.50505@toya.net.pl> Date: Tue, 4 Jan 2011 22:11:42 +0000 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: WSPR Reports Content-Type: multipart/alternative; boundary=90e6ba53a55eab930d04990c8d16 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=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-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-m251.1 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1db40e4d239b6573f0 X-AOL-IP: 195.171.43.25 X-Mailer: Unknown (No Version) --90e6ba53a55eab930d04990c8d16 Content-Type: text/plain; charset=ISO-8859-1 Some tests that were done a while back on this issue by several WSPR users, suggested, that the WSPR noise was measured in a bandwidth a little over the 200 Hz needed for the signalling- something like 250 - 300Hz. 300Hz wide CW filters made a fraction of a dB difference, compared with an SSB filter used as a reference; a 200Hz wide filter gave 0.5 - 1dB as far as I remember, and a 100Hz or narrower filter gave ridiculous errors. So WSPR reallt ought to be decoded with an IF filter in excess of 300Hz - ie a medium - wide CW filter. The typing of frequencies into windows is not important to the S/W; only affecting the reported and subsequent tansmission frequency. All the WSPR decoding software does is look at audio tones in the range 1400 - 1600Hz. I really would encourage people to NOT use narow filter when using the mode. Strong signals within an SSB bandwidth do not influence teh decoding process PROVIDED they a) do not shift AGC (which should really be off anyway) and do not cause overload / clipping of the A/D. A bog-standard 16 bit soundcard can manage 80dB dynamic range, so things would have to be pretty serious to exceed that in 3kHz. Andy www.g4jnt.com On 4 January 2011 21:37, Piotr Mlynarski wrote: > Andy Talbot pisze: > >> Looking at the WSPR database, F6CNI is decoding me consistently in the 0dB >> S/N region. At 391km this can't be realistic, and most likely comes from >> using a narrow filter - sub 200Hz - before feeding audio to the decoding >> software. The WSPR software does need a flat audio response in the 1400 - >> 1600Hz range, and preferably over the complete SSB bandwidth. >> Andy >> www.g4jnt.com >> >> > Andy, LF group > > i do not have at hand the wspr source code at this moment but as i remember > it is a 'simple' addition/substraction of 1500 > in the decoding/encoding scheme as the 'real' band in the program is > between (-100 Hz; +100Hz) > As i do not TX (yet! :) ) on 137 khz and use WSPR only for RX'ing > it is , say, 'convenient' , to put your TRX into CW mode > and use narrow filters to get rid of qrm otherwise being hard to kill when > using wide (ssb) passband > > the issue of feedeing the wspr database with correct freq. is solved by > typing in the rx window the difference between your bfo offset > and the rf carrier frequency > suppose, you are using ssb mode and the rf carrier is on 137.500 kHz so in > order to rx this, you type in the rx window 136.000 khz > tx window 137.500 ; your trx is in usb mode and in the range 1400-1600 you > look for the wspr signal > > now , you set your trx in CW mode and your BFO offset is 600 Hz , so you > type 136.900 in rx window instead of nominal 136.000 > and the report yields correct freq. spot /136900 Hz + 600Hz = 137500Hz/ > (probably, in some rx hardware the left/right injection of bfo may be an > 'algebraic' problem... ) > > Finally, > all the wspr S/N reports are presumably reffered to a 2500Hz wide passband. > of course, the s/n report when using 500/250 cw filter is useless... > but.... all the modern, black, trx boxes have variable SSB filters so it > is hard to believe that everybody is using a unified 2.4 or 2.7 khz filter > also, those modern boxes have another feature named PBT ( pass band tuning) > Using it you may cut-off a good part of your 2500 Hz filter either from > below or above > the desired freqency so again, the reported s/n in such cases is > questionable... > in my view , the wspr is a weak signal mode - the real challenge is , > therefore, to get positive decode of a transmitted signal using all > accessible measures > (filters,amplifiers, etc...) thus making the reported s/n rather of > secondary importance .. > the above statement was reffered to 137/500 khz bands. > on classical HF bands things look probably better , being more unified .. > > 73, Piotr,sq7mpj > qth: Lodz /jo91rs/ > > > --90e6ba53a55eab930d04990c8d16 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Some tests that were done a while back on this issue by several WSPR= users, suggested, that the WSPR noise was measured in a bandwidth a littl= e over the 200 Hz needed for the signalling- something like 250 - 300Hz.= =A0=A0=A0
=A0
300Hz wide CW filters made a fraction of a dB difference, compared wi= th an SSB filter used as a reference;
a=A0200Hz wide filter=A0gave=A00.5 - 1dB as far as=A0I remember,=A0= and a 100Hz or narrower filter=A0gave ridiculous errors.=A0=A0 So WSPR re= allt ought to be decoded with an IF filter in excess of 300Hz - ie a mediu= m - wide CW filter.
=A0
The=A0typing of frequencies into windows is not important to the S/W;= only affecting=A0the reported and subsequent tansmission frequency.=A0 Al= l the WSPR decoding software does is look at audio tones in the range 1400= - 1600Hz.
=A0
I really would encourage people to NOT use narow filter when using th= e mode.=A0=A0=A0 Strong signals within an SSB bandwidth do not influence= teh decoding process PROVIDED they a) do not shift AGC (which should real= ly be off anyway) and do not cause overload / clipping=A0of the A/D.=A0=A0= =A0 A bog-standard 16 bit soundcard can manage 80dB dynamic range, so thin= gs would have to be pretty serious to exceed that in 3kHz.
=A0
Andy
=A0

On 4 January 2011 21:37, Piotr Mlynarski <sq7mpj@toya.net.pl<= /a>> wrote:
Andy Talbot pisze:
Looking at the WSPR database,= F6CNI is decoding me consistently in the 0dB S/N region. =A0 At 391km thi= s can't be realistic, and most likely comes from using a narrow filter= - sub 200Hz - before feeding audio to the decoding software. =A0 =A0The= WSPR software does need a flat audio response in the 1400 - 1600Hz range,= and preferably over the complete SSB bandwidth.
=A0Andy
www.g4jnt.c= om <http://www.= g4jnt.com/>
=A0
Andy, LF group

i do not= have at hand the wspr source code at this moment but as i remember it is= a =A0'simple' addition/substraction of 1500
in the decoding/encoding scheme as the 'real' =A0band in the progr= am is between =A0(-100 Hz; +100Hz)
As i do not =A0TX (yet! =A0:) =A0)= =A0on =A0137 khz =A0and use WSPR =A0only for =A0RX'ing it is , say,= =A0'convenient' , =A0to put your TRX =A0into CW mode
and use narrow filters to get rid of qrm otherwise being hard to kill =A0w= hen using wide (ssb) passband

the issue of feedeing the wspr databa= se with correct freq. is solved by typing in the rx window the difference= between your bfo offset
and the rf carrier frequency
suppose, you are using ssb mode =A0and the= rf carrier is on 137.500 kHz so in order to rx this, =A0 you type in the= rx window 136.000 khz
tx window 137.500 ; your trx is in usb mode and= in the range 1400-1600 you look for the wspr signal

now , you set your trx in CW mode and your BFO offset is 600 Hz , so= you type =A0136.900 in rx window =A0instead of nominal 136.000
and the= report yields correct freq. spot =A0 /136900 Hz + 600Hz =3D 137500Hz/
= (probably, in some rx hardware the left/right injection of bfo may be an= 'algebraic' =A0problem... )

Finally,
all the wspr S/N reports are presumably reffered to a 2500= Hz wide passband. =A0of course, the =A0s/n report when using 500/250 cw fi= lter is useless...
but.... all the modern, black, =A0trx boxes have var= iable SSB filters so it is hard to believe that everybody is using a unifi= ed 2.4 or 2.7 khz filter
also, those modern boxes have another feature named PBT ( pass band tuning= ) Using it you may =A0cut-off a good part of your 2500 Hz filter either fr= om below or above
the desired freqency =A0so again, the reported s/n in= such cases is questionable...
in my view , the wspr is a weak signal mode - the real challenge is , ther= efore, to get positive decode of a transmitted signal using all accessible= measures
(filters,amplifiers, etc...) =A0 thus making the reported s/n= =A0rather of secondary importance ..
the above statement was reffered to 137/500 khz bands.
on classical HF= bands things look probably better , being more unified ..
=A0 =A0 =A0= =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0= =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0= =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0= =A0 =A0 =A0 =A0 =A0 =A0 73, Piotr,sq7mpj
qth: Lodz =A0/jo91rs/



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