Return-Path: Received: from mtain-dk04.r1000.mx.aol.com (mtain-dk04.r1000.mx.aol.com [172.29.180.8]) by air-da07.mail.aol.com (v129.10) with ESMTP id MAILINDA073-863f4db8887bb9; Wed, 27 Apr 2011 17:19:55 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dk04.r1000.mx.aol.com (Internet Inbound) with ESMTP id 35A17380000B9; Wed, 27 Apr 2011 17:19:54 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1QFC80-0000jx-8f for rs_out_1@blacksheep.org; Wed, 27 Apr 2011 22:18:32 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1QFC7z-0000jo-Ij for rsgb_lf_group@blacksheep.org; Wed, 27 Apr 2011 22:18:31 +0100 Received: from mail-iw0-f171.google.com ([209.85.214.171]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1QFC7x-0007Rh-9M for rsgb_lf_group@blacksheep.org; Wed, 27 Apr 2011 22:18:31 +0100 Received: by iwn8 with SMTP id 8so2675126iwn.16 for ; Wed, 27 Apr 2011 14:18:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:in-reply-to:references:date :message-id:subject:from:to:content-type; bh=Hm0RHLyDZt4br7V0dUxBrQGXbkdjL0n+3q9LREctgyM=; b=ROD1C9oAI00sxG+sON3jGTrZy8oAxEc7cbMTNbeSBDbxEJgzOYhWdcNjRIDuWdhTqz Ay7A2niNXMaJmGUiYZMVtCseVlcQcI4O9UUS10ASLa3voWXi5a6H4xmcm/xyhIlVRtYu v9cFdDtu4ZI4R2xtMo6RgHHsPj6vbqXD0FwwE= 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=RXEXQwoX3r2P7o7NOAqzlFQYxoqBR7B82Daf78MO9ZYk0fNP82fC+UXcUKfwxz4eJY fj70Fth/56jpA0/ygpni8wLf0V2Ozc7I9vdDJZ2DUdTL8zGjM1tpJo2eXIlrndYd2s9C +1pZUdHt87K+06f1c7hBZFlxDDWHefAaPx7WI= MIME-Version: 1.0 Received: by 10.42.243.3 with SMTP id lk3mr3336472icb.161.1303939103022; Wed, 27 Apr 2011 14:18:23 -0700 (PDT) Received: by 10.231.207.75 with HTTP; Wed, 27 Apr 2011 14:18:22 -0700 (PDT) In-Reply-To: References: <4DB8535B.7040903@talktalk.net> <4DB873DB.500@talktalk.net> Date: Wed, 27 Apr 2011 22:18:22 +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: More 8.97kHz WSPR decodes - changed PC here Content-Type: multipart/alternative; boundary=90e6ba3fcc4f0b5d5e04a1ecfbe6 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_20_30,HTML_MESSAGE, LINES_OF_YELLING 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-m286.1 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1db4084db888796ce9 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --90e6ba3fcc4f0b5d5e04a1ecfbe6 Content-Type: text/plain; charset=ISO-8859-1 First calculate S/N alone : WSPR has a signalling bandwidth of 1.46Hz which is the value to use for noise level calculation. QRSS600 has a bandwidth of 0.0017Hz. They both rely on non-coherent power detection, so assume equal detection sensitivity. On S/N alone QRSS600 is therefore 10.LOG(1.46/.0017) = 29dB better than WSPR. BUT. Soft decision decoding and error correction in WSPR allows perfect copy at S/N of about 4dB in 1.46Hz (== -28dB in 2500Hz for comparison). QRSS needs about 10 - 12dB, so in terms of coding efficiency, QRSS is 7dB worse. Combining the two gives a total sensitivity imprevement of 29 - 7 = 22dB for QRSS600 over WSPR Of course, if time of transmission needs to be taken into account the rules change completely........ Andy G4JNT On 27 April 2011 21:45, Roger Lapthorn wrote: > Dear Eddie (et al) > > In the context of the *very very* weak signals experienced at VLF I don't > think WSPR is a serious contender except for localised tests. No doubt > someone here far more knowledgeable than me can tell us the "dB advantage" > of say, QRSS600 or 6000 versus WSPR, but the difference must be enormous. > > Where WSPR scores, in my view, is the automatic reporting via the internet > database. This has proved a real boon at 137 and 500kHz. Even here though > very slow QRSS would beat WSPR every time. I am a great believer in WSPR, > but do not believe it will be that much use at VLF. > > Andy (G4JNT) are you able to comment on please? > > 73s > Roger G3XBM > > > > > > On 27 April 2011 20:51, qrss wrote: > >> Just a further thought. WSPR doesn't of course spread its power over 6Hz >> it actually transmits full carrier on each of the four frequencies for 0.682 >> mS and sometimes several of the same element follow without a break in >> carrier, which accounts for some of the bright spots and lines we see when >> things are marginal. One element is a longer dot time than 2WPM Morse, and >> that is SLOW Morse. >> Long integration times are out of course. >> >> 73 Eddie G3ZJO >> >> >> On 27/04/2011 18:58, Roger Lapthorn wrote: >> >> Hi Eddie (et al) >> >> It is highly unlikely you'd copy Andrew on VLF remembering that the WSPR >> signal spreads around 6Hz in the transmission burst, so the energy in any >> narrow FFT bin would be tiny. Also, this is earth mode (I hope, as G6ALB >> does not hold an NoV to radiate at VLF), so signals are propagating through >> the ground by conduction and no significant amount of signal is radiated. >> >> I'm still intrigued why the best reception here today was with my 80sq m >> vertical loop. This outperformed several earth electrode set-ups here at the >> RX end, an E-field probe and a 30t loop laying close to copper pipe work in >> the house! If the signals are coming down the pipes then why don't these >> more direct means of coupling to them work as well as (or better than) a >> vertical loop outside? Odd. >> >> 73s >> Roger G3XBM >> >> >> >> On 27 April 2011 18:33, qrss wrote: >> >>> Great stuff Roger and Andrew >>> >>> If you are RX'ing on an 80m dipole it may be worth a look here, I would >>> never say can't until I have tried. Bearing in mind I should be able to >>> observe signals which would not be decode able on WSPR >>> >>> I would appreciate a prior notification of times and exact frequency of >>> the WSPR signal of any further tests. >>> >>> Keep it up. >>> >>> 73 Eddie G3ZJO >>> >>> >>> On 27/04/2011 15:19, Roger Lapthorn wrote: >>> >>>> As an experiment I changed over to my wife's laptop and got immediate >>>> decodes of G6ALB's VLF earth mode signal (3km) at -17dB S/N, suggesting the >>>> issue with lack of decodes may be with my soundcard and not Andrew's. >>>> >>>> 1408 -17 -0.6 0.008986 0 G6ALB JO02 47 >>>> 1410 -17 -0.6 0.008986 0 G6ALB JO02 47 >>>> 1412 -17 -1.2 0.008986 0 G6ALB JO02 47 >>>> 1414 -17 -0.8 0.008986 0 G6ALB JO02 47 >>>> 1416 -17 -0.8 0.008986 0 G6ALB JO02 47 >>>> >>>> This is a very solid signal on the 80m square single turn vertical wire >>>> loop antenna. Andrew is using 44W to an earth electrode antenna. >>>> >>>> 73s >>>> Roger G3XBM >>>> >>>> -- >>>> http://g3xbm-qrp.blogspot.com/ >>>> http://www.g3xbm.co.uk >>>> http://www.youtube.com/user/g3xbm >>>> https://sites.google.com/site/sub9khz/ >>>> >>>> >>> >>> >> >> >> -- >> http://g3xbm-qrp.blogspot.com/ >> http://www.g3xbm.co.uk >> http://www.youtube.com/user/g3xbm >> https://sites.google.com/site/sub9khz/ >> >> >> > > > -- > http://g3xbm-qrp.blogspot.com/ > http://www.g3xbm.co.uk > http://www.youtube.com/user/g3xbm > https://sites.google.com/site/sub9khz/ > > --90e6ba3fcc4f0b5d5e04a1ecfbe6 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
First calculate S/N alone :
WSPR has a signalling bandwidth of 1.46Hz which is the value to use= for noise level calculation.=A0=A0=A0
QRSS600 has a bandwidth of 0.0017Hz.=A0 They both rely on non-coheren= t power detection, so assume equal detection sensitivity.
On S/N alone QRSS600 is therefore 10.LOG(1.46/.0017)=A0 =3D=A0 29dB= better than WSPR.
=A0
BUT.
Soft decision decoding and error correction in WSPR allows perfect co= py at S/N of about 4dB=A0in 1.46Hz=A0(=3D=3D -28dB in 2500Hz for compariso= n).
QRSS needs about 10 - 12dB, so in terms of coding efficiency, QRSS is= 7dB worse.
=A0
Combining the two gives a total sensitivity imprevement of 29 - 7 =3D= 22dB for QRSS600 over WSPR
Of course, if time of transmission needs to be taken into account the= rules change completely........
=A0
Andy=A0=A0=A0 G4JNT


=A0
On 27 April 2011 21:45, Roger Lapthorn <rogerlapthorn@gma= il.com> wrote:
Dear Eddie (et al)

In= the context of the very very weak signals experienced at VLF I don= 't think WSPR is a serious contender except for localised tests. No do= ubt someone here far more knowledgeable than me can tell us the "dB= advantage" of say, QRSS600 or 6000 versus WSPR, but the difference= must be enormous.

Where WSPR scores, in my view, is the automatic reporting via the inte= rnet database. This has proved a real boon at 137 and 500kHz. Even here th= ough very slow QRSS would beat WSPR every time.=A0 I am a great believer= in WSPR, but do not believe it will be that much use at VLF.

Andy (G4JNT) are you able to comment on please?

73s
Roger G3= XBM=20





On 27 April 2011 20:51, qrss = <qrss@talktalk.n= et> wrote:
Just a further thought. WSPR doe= sn't of course spread its power over 6Hz it actually transmits full ca= rrier on each of the four frequencies for 0.682 mS and sometimes several= of the same element follow without a break in carrier, which accounts for= some of the bright spots and lines we see when things are marginal. One= element is a longer dot time than 2WPM Morse, and that is SLOW Morse.
Long integration times are out of course.

73 Eddie G3ZJO
=A0=20

On 27/04/2011 18:58, Roger Lapthorn wrote:
Hi Eddie (et al)

It is highly unlikely yo= u'd copy Andrew on VLF remembering that the WSPR signal spreads around= 6Hz in the transmission burst, so the energy in any narrow FFT bin would= be tiny. Also, this is earth mode (I hope, as G6ALB does not hold an NoV= to radiate at VLF), so signals are propagating through the ground by cond= uction and no significant amount of signal is radiated.

I'm still intrigued why the best reception here today was with my= 80sq m vertical loop. This outperformed several earth electrode set-ups= here at the RX end, an E-field probe and a 30t loop laying close to coppe= r pipe work in the house!=A0 If the signals are coming down the pipes then= why don't these more direct means of coupling to them work as well as= (or better than) a vertical loop outside? Odd.

73s
Roger G3XBM



On 27 April 2011 18:33, qrss = <qrss@talktalk.n= et> wrote:
Great stuff Roger= and Andrew

If you are RX'ing on an 80m dipole it may be worth= a look here, I would never say can't until I have tried. Bearing in= mind I should be able to observe signals which would not be decode able= on WSPR

I would appreciate a prior notification of times and exact frequency= of the WSPR signal of any further tests.

Keep it up.

73 Edd= ie G3ZJO=20


On 27/04/2011 15:19, Roger Lapthorn wrote:
As an experiment= I changed over to my wife's laptop and got immediate decodes of G6ALB= 's VLF earth mode signal (3km) at -17dB S/N, suggesting the issue with= lack of decodes may be with my soundcard and not Andrew's.

1408 -17 -0.6 =A0 0.008986 =A00 G6ALB JO02 47
1410 -17 -0.6 =A0 0.0= 08986 =A00 G6ALB JO02 47
1412 -17 -1.2 =A0 0.008986 =A00 G6ALB JO02 47<= br>1414 -17 -0.8 =A0 0.008986 =A00 G6ALB JO02 47
1416 -17 -0.8 =A0 0.00= 8986 =A00 G6ALB JO02 47

This is a very solid signal on the 80m square single turn vertical wir= e loop antenna. Andrew is using 44W to an earth electrode antenna.

= 73s
Roger G3XBM

--
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.= uk
= http://www.youtube.com/user/g3xbm
https://sites.google.com/site/sub9khz/=






--
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www= .youtube.com/user/g3xbm
https://sites.google.com/site/sub9khz/




--
= http://g3xbm-= qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www= .youtube.com/user/g3xbm
https://sites.google.com/site/sub9khz/

--90e6ba3fcc4f0b5d5e04a1ecfbe6--