Return-Path: Received: from mtain-df03.r1000.mx.aol.com (mtain-df03.r1000.mx.aol.com [172.29.64.215]) by air-dc07.mail.aol.com (v129.10) with ESMTP id MAILINDC073-86534db889db26d; Wed, 27 Apr 2011 17:25:47 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-df03.r1000.mx.aol.com (Internet Inbound) with ESMTP id AF914380000BB; Wed, 27 Apr 2011 17:25:45 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1QFCEA-0000qH-JM for rs_out_1@blacksheep.org; Wed, 27 Apr 2011 22:24:54 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1QFCE9-0000q8-OO for rsgb_lf_group@blacksheep.org; Wed, 27 Apr 2011 22:24:53 +0100 Received: from mail-iw0-f171.google.com ([209.85.214.171]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1QFCE7-0007Y8-C1 for rsgb_lf_group@blacksheep.org; Wed, 27 Apr 2011 22:24:53 +0100 Received: by iwn8 with SMTP id 8so2681851iwn.16 for ; Wed, 27 Apr 2011 14:24:45 -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=6IaZ0qArXbzb9lhIvY5fQ3DbGwxEvq6wZr7+NH4WlkA=; b=Ok5yMWD3TZNbdw+Y9WTOK/Fne6YNvVZhidGMBAQdN96dfl2c5z/i36zUVMtQTAk/XN pv+pV0fGuozO8BDUDUGZwRqUMZHknXlCw3UxG2ajhuAGScaSXcnFFa7LyuWDO7tM7k20 VL44Rnx//0crrdPajTzFVDi2K9ImPoYTHikmg= 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=uJIpYjgJTAYPn9IWfgDEZZGydYRveA56GoBnZ4Io64o9EPuHnRlu58TzXtoUXJcZ0h QNbtY2BnhYiYqQGE/WRFcbjo1dZWebBaAlyb3NfF7bX4pKxvZtqSqzIJAp8ov/lcBzcm RQ6Zo4KPAH1PLAKi6gWA1HKudb/txuVS9tdTQ= MIME-Version: 1.0 Received: by 10.42.19.196 with SMTP id d4mr1085429icb.113.1303939484752; Wed, 27 Apr 2011 14:24:44 -0700 (PDT) Received: by 10.42.221.133 with HTTP; Wed, 27 Apr 2011 14:24:44 -0700 (PDT) In-Reply-To: References: <4DB8535B.7040903@talktalk.net> <4DB873DB.500@talktalk.net> Date: Wed, 27 Apr 2011 22:24:44 +0100 Message-ID: From: Roger Lapthorn 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=20cf3040ee4acc1af904a1ed11c3 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-m219.1 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d40d74db889d90df7 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --20cf3040ee4acc1af904a1ed11c3 Content-Type: text/plain; charset=ISO-8859-1 Andy/Marcus Many thanks for your most interesting analysis. 73s Roger G3XBM On 27 April 2011 22:18, Andy Talbot wrote: > 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/ >> >> > -- http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/g3xbm https://sites.google.com/site/sub9khz/ --20cf3040ee4acc1af904a1ed11c3 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Andy/Marcus

Many thanks for your most interesting analysis.

= 73s
Roger G3XBM

On 27 April 2011 22:1= 8, Andy Talbot <andy.g4jnt@gmail.com> wrote:
First calc= ulate 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@gmail.com> wrote:
Dear Eddie (et= al)

In the context of the very very weak signals experience= d at VLF I don't think WSPR is a serious contender except for localise= d 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 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 Rog= er and Andrew

If you are RX'ing on an 80m dipole it may be wort= h 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 experimen= t I changed over to my wife's laptop and got immediate decodes of G6AL= B's VLF earth mode signal (3km) at -17dB S/N, suggesting the issue wit= h 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/




--
http://g3xbm-qrp.blogsp= ot.com/
http:/= /www.g3xbm.co.uk
http://www= .youtube.com/user/g3xbm
https://sites.google.com/site/sub9khz/
--20cf3040ee4acc1af904a1ed11c3--