Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dh01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 2ED1C3800009C; Wed, 24 Aug 2011 18:21:25 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1QwLoJ-00014o-Ps for rs_out_1@blacksheep.org; Wed, 24 Aug 2011 23:20:35 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1QwLoI-00014f-OM for rsgb_lf_group@blacksheep.org; Wed, 24 Aug 2011 23:20:34 +0100 Received: from mail-wy0-f171.google.com ([74.125.82.171]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1QwLoF-0001kl-VD for rsgb_lf_group@blacksheep.org; Wed, 24 Aug 2011 23:20:34 +0100 Received: by wyh13 with SMTP id 13so1946866wyh.16 for ; Wed, 24 Aug 2011 15:20:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=subject:references:from:content-type:x-mailer:in-reply-to :message-id:date:to:content-transfer-encoding:mime-version; bh=+7LT0lbf5kkkreiwIgu4xystxEvO71gfVlvMs0S86UE=; b=jiIFuGqefXi6YlSx8V6oiB+kThJcZhT9Ylqrig7mn7z0XVn3uqdv0vFcY3r26naDM8 u90e+qk1Eb6abEPApE+ZJ1v+dgGYXKMDazo1Z7JB6Kv3oHhBkJEsCZpOUInXcjrRFpo4 91k4X9Ydq3yVdDzs8hkaLyCrkEKlIUmVCxor8= Received: by 10.216.36.19 with SMTP id v19mr1077639wea.14.1314224426010; Wed, 24 Aug 2011 15:20:26 -0700 (PDT) Received: from [192.168.1.100] (cpc2-cmbg13-0-0-cust876.5-4.cable.virginmedia.com [213.106.115.109]) by mx.google.com with ESMTPS id fg5sm1203773wbb.40.2011.08.24.15.20.23 (version=TLSv1/SSLv3 cipher=OTHER); Wed, 24 Aug 2011 15:20:24 -0700 (PDT) References: <790E5582101F4A069156B4677843CD78@AGB> <007f01cc6286$0f541490$0401a8c0@xphd97xgq27nyf> <1314211001.22166.YahooMailNeo@web125716.mail.ne1.yahoo.com> <4E55742F.9060103@iup.uni-heidelberg.de> From: Roger Lapthorn X-Mailer: iPod Mail (8F190) In-Reply-To: <4E55742F.9060103@iup.uni-heidelberg.de> Message-Id: Date: Wed, 24 Aug 2011 23:21:12 +0100 To: "rsgb_lf_group@blacksheep.org" Mime-Version: 1.0 (iPod Mail 8F190) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: WSPR or QRSS: which is better? Content-Type: multipart/alternative; boundary=Apple-Mail-1-909826627 Content-Transfer-Encoding: 7bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.9 required=5.0 tests=HTML_30_40, HTML_FONTCOLOR_UNSAFE,HTML_MESSAGE,TO_ADDRESS_EQ_REAL 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-SCORE: 0:2:470958400:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d250.1 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d41154e5579651154 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --Apple-Mail-1-909826627 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 Yes I agree Stefan.=20 I just wanted a clear answer from someone like Andy regarding the theoretica= l difference between WSPR (with it's strong error correction) and QRSS at va= rious speeds. In the limit very slow QRSS is bound to win but WSPR allows a l= ot of data to be fed back to the TX station immediately after just a 110sec b= urst.=20 Still to try ROS! 73s Roger G3XBM Via my iPod Touch 4g 2.4GHz handheld.=20 On 24 Aug 2011, at 22:59, Stefan Sch=C3=A4fer wrote: > Hello Roger,=20 >=20 > OK about WSPR beeing about equal to QRSS-3 in sensitivity. >=20 > But if you just want to test how far you can get with your signal, why don= 't you try QRSS-60? This must have an improvement of > 10 dB and there are p= lenty of grabbers running arround your QTH. G4WGT, F1AFJ, DK7FC, DF6NM, OE3G= HB.... We all are monitoring the band sectors all the time. Everybody can re= ad the signals, meaningless if QRSS or DFCW or slow hell... You can even hav= e an offset of say 2 Hz or a drift of say 1 Hz/hour. The grabbers are runnin= g anyway, so you don't even have to ask for listening stations if you want t= o do tests... >=20 > Isn't that even simpler and ideal for such tests?=20 >=20 > 73, Stefan/DK7FC >=20 > Am 24.08.2011 20:56, schrieb Roger Lapthorn: >>=20 >> Hi Marcelino >>=20 >> Thanks for this.=20 >>=20 >> Yes I understand fully what is needed for LF/MF WSPR and have implemented= simple and low cost WSPR solutions using transverters for both 136 and 500k= Hz with some excellent results on the latter band - see my website for detai= ls. On 136kHz WSPR my best DX is 148km with a VERY low ERP and simple antenn= a.=20 >>=20 >> This autumn I am improving the ERP on both bands and hope to better my DX= on WSPR considerably. I also confidently predict that the system improvemen= ts will allow me to have my first CW QSO with G3KEV and others on 136kHz. I h= ave already worked him on 500kHz CW with 1mW ERP thanks to his good ears and= good system and antennas. >>=20 >> 73s >> Roger G3XBM >>=20 >>=20 >>=20 >> On 24 August 2011 19:36, Marcelino Garcia wrote: >> Roger, >> I fully agree with your statements, but I'm afraid that with a= minimalist home made CW transmitter, let's say just a one transistor xtal o= scillator, it's not possible to use WSPR, for this mode a little more compl= ex transmitter, may be SDR based, should be used. >> 73, >> Marcelino - LU7DSU >>=20 >> De: Roger Lapthorn >> Para: rsgb_lf_group@blacksheep.org >> Enviado: mi=C3=A9rcoles, 24 de agosto de 2011 15:18 >> Asunto: Re: LF: WSPR or QRSS: which is better? >>=20 >> Mal >>=20 >> Thanks again for your comments, some of which are valid. =20 >>=20 >> There are times when CW is useful and times when more efficient modes lik= e WSPR really win out.=20 >>=20 >> As I have said countless times now, no other mode apart from WSPR that I k= now of is able to give me almost instant feedback (via the internet database= ) at a distance that (a) my signal is being received at all, (b) how far it i= s getting, and (c) how strong it is. To be able to get this information when= using simple, low powered and home made equipment is extremely useful. A sm= all change in the PA output or antenna efficiency is measurable.=20 >>=20 >> It really comes down to what is the purpose of our experiments: being abl= e to make CW contacts is a perfectly reasonable aim - please carry on. In my= case it is to see just what is possible with minimalist (hardware) equipmen= t on the VLF, LF and MF bands. Yes, I am gaining valuable dBs by the use of e= fficient coding systems and clever PC software, but I see nothing wrong in t= hat. >>=20 >> And finally, please do NOT call me an appliance operator: all my VLF-MF e= quipment is home-made as is much of my HF and VHF gear. I am happy to use mo= dern technology to enhance my enjoyment of the hobby and to exploit weak sig= nal modes but I am equally happy to have a CW QSO on any band when the oppor= tunity arises. >>=20 >> 73s >> Roger G3XBM >>=20 >>=20 >>=20 >> On 24 August 2011 18:48, mal hamilton wrote: >> Jim take NOTE >> Impulsive noise generates a random output that looks like a valid callsig= n so this is also inventing a signal that you imagine to exist. >> An immediate positive ID, don't depend on it !! >> An appliance communications operator is easily hoodwinked. >> Bletchley Park CW expert Radio Operators managed to piece messages toget= her and achieved the object., and no doubt used imagination. >> No expertise is need to send/receive wspr and for that matter a lot of ot= her appliance operator modes, know in the services today as IDIOT PROOF comm= s black boxes. >> For a commercial operator that needs to shift thousands of messages world= wide then automated digital modes are necessary and useful, but for a radio h= obbyist its like using a sledge hammer to crack the proverbial nut >> =20 >> g3kev >> =20 >> =20 >> =20 >> =20 >> Original Message ----- >> From: Andy Talbot >> To: rsgb_lf_group@blacksheep.org >> Sent: Wednesday, August 24, 2011 6:06 PM >> Subject: Re: LF: WSPR or QRSS: which is better? >>=20 >> I know what you're referring to. In cases of impulsive noise, there is a= finite probability of something eventually getting through the decoder and= being flagged as valid. The very nature of heavy source coding, means that= the resulting random output will look like a valid callsign. However, WE t= hen apply the next level of error detection, by knowing the combination must= be rubbish. >> =20 >> 'jnt [and there is another example of source coding] >>=20 >>=20 >> =20 >> On 24 August 2011 17:47, Graham wrote: >> >> and gives absolutely guaranteed error free decoding, or nothing at al= l. << >> =20 >> Are you sure ?=20 >> =20 >> G.. >>=20 >> From: Andy Talbot >> Sent: Wednesday, August 24, 2011 5:12 PM >> To: rsgb_lf_group@blacksheep.org =20 >> Subject: Re: LF: WSPR or QRSS: which is better? >>=20 >> WSPR works in a 1.46Hz signal bandwidth and because of its very high leve= l of error correction and soft-decision decoding, means that it will work at= a S/N of about 3dB in this bandwidth, and sometimes a bit lower still (Nor= mally, FSK with no correction at all needs about 10 - 12dB S/N for near erro= r-free performance) >> =20 >> QRSS has to show about 6 - 10dB in its signal bandwidth to be able to dis= cern fully what is sent, although a slightly lower S/N may be useable when y= ou 'know' what you should be receiving. (A form of forward error correction= is now in use here as well perhaps :-) So lets say 5dB S/N is a working va= lue.. >> =20 >> So take 3dB in 1.46Hz as a starting point and derive the bandwidth for QR= SS needed to get 5dB S/N with the same signal. This will have to be narrowe= r to get a 2dB higher S/N and works out as 1.46 / 10^(2/10) =3D 0.92Hz >> =20 >> So QRSS used with a 0.9Hz bandwidth - which I think means about a 2 - 3s d= ot period ought to be decoded at the same S/N as a WSPR signal. Which is p= robably the info you wanted. >> =20 >> But now compare source coding efficiencies. WSPR fits a callsign, locat= or and power level into a 110 second transmission - and gives absolutely gua= ranteed error free decoding, or nothing at all. About 12 characters in actu= ality, but that is being a bit unfair as the coding forces certain callsign a= nd locator formatting. So in all probablility, more like 7 or 8 effective c= haracters (I'm being a bit empirical here) >> =20 >> Assuming standard QRSS - not DFCW - , which if like standard Morse, then 5= characters takes about 50 dot symbols to send (12WPM =3D 60 chars in 1 minu= te, =3D 1 char / second, or about 10 dot periods / second. Dot speed =3D W= PM / 1.2) If we have 2s dots, that is 5 characters can be sent in the time= for a WSPR transmission. >> =20 >> So as a quick estimate, WSPR wins by roughly 2dB in S/N terms for a given= dot period / noise bandwidth. And at similar S/N values, WSPR is about 1.5= times faster >> Andy >> www.g4jnt.com >> =20 >> =20 >> =20 >> =20 >> On 24 August 2011 16:42, Roger Lapthorn wrote: >> A question for the coding experts here: WSPR is an excellent weak signal b= eaconing mode, but at what QRSS speed is QRSS "better" ? >>=20 >> 73s >> Roger G3XBM >>=20 >> --=20 >> http://g3xbm-qrp.blogspot.com/ >> http://www.g3xbm.co.uk >> http://www.youtube.com/user/g3xbm >> https://sites.google.com/site/sub9khz/ >>=20 >>=20 >>=20 >>=20 >>=20 >>=20 >>=20 >>=20 >> --=20 >> http://g3xbm-qrp.blogspot.com/ >> http://www.g3xbm.co.uk >> http://www.youtube.com/user/g3xbm >> https://sites.google.com/site/sub9khz/ >>=20 >>=20 >>=20 >>=20 >>=20 >>=20 >> --=20 >> http://g3xbm-qrp.blogspot.com/ >> http://www.g3xbm.co.uk >> http://www.youtube.com/user/g3xbm >> https://sites.google.com/site/sub9khz/ >>=20 >=20 --Apple-Mail-1-909826627 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8
Yes I agree Stefan. 
I just wanted a clear answer from someone like Andy regarding th= e theoretical difference between WSPR (with it's strong error correction) an= d QRSS at various speeds. In the limit very slow QRSS is bound to win but WS= PR allows a lot of data to be fed back to the TX station immediately after j= ust a 110sec burst. 

Still to try ROS!

=
73s
Roger G3XBM

Via my iPod To= uch 4g 2.4GHz handheld. 

On 24 Aug 2011, at 22:59, Stefan= Sch=C3=A4fer<St= efan.Schaefer@iup.uni-heidelberg.de> wrote:

<= blockquote type=3D"cite">
Hello Roger,

OK about WSPR beeing about equal to QRSS-3 in sensitivity.

But if you just want to test how far you can get with your signal, why don't you try QRSS-60? This must have an improvement of > 10 dB and there are plenty of grabbers running arround your QTH. G4WGT, F1AFJ, DK7FC, DF6NM, OE3GHB.... We all are monitoring the band sectors all the time. Everybody can read the signals, meaningless if QRSS or DFCW or slow hell... You can even have an offset of say 2 Hz or a drift of say 1 Hz/hour. The grabbers are running anyway, so you don't even have to ask for listening stations if you want to do tests...

Isn't that even simpler and ideal for such tests?

73, Stefan/DK7FC

Am 24.08.2011 20:56, schrieb Roger Lapthorn:
Hi Marcelino

Thanks for this.

Yes I understand fully what is needed for LF/MF WSPR and have implemented simple and low cost WSPR solutions using transverters for both 136 and 500kHz with some excellent results on the latter band - see my website for details. On 136kHz WSPR my best DX is 148km with a VERY low ERP and simple antenna.

This autumn I am improving the ERP on both bands and hope to better my DX on WSPR considerably. I also confidently predict that the system improvements will allow me to have my first CW QSO with G3KEV and others on 136kHz. I have already worked him on 500kHz CW with 1mW ERP thanks to his good ears and good system and antennas.

73s
Roger G3XBM



On 24 August 2011 19:36, Marcelino Garcia <lu7dsu@yahoo.com.ar><= /span> wrote:
Roger,
          &= nbsp; I fully agree with your statements, but I'm afraid that with a minimalist home made CW transmitter, let's say just a one transistor xtal oscillator, it's not  possible to use WSPR, for this mode a little more complex transmitter, may be SDR based, should be used.
73,
Marcelino - LU7DSU

De: Roger Lapthorn <roge= rlapthorn@gmail.com>
Para: rsgb_lf_group@blacksheep.org
Enviado: mi=C3=A9rcoles= , 24 de agosto de 2011 15:18
Asunto: Re: LF: WSPR or QRSS: which is better?

Mal

Thanks again for your comments, some of which are valid. 

There are times when CW is useful and times when more efficient modes like WSPR really win out.

As I have said countless times now, no other mode apart from WSPR that I know of is able to give me almost instant feedback (via the internet database) at a distance that (a) my signal is being received at all, (b) how far it is getting, and (c) how strong it is. To be able to get this information when using simple, low powered and home made equipment is extremely useful. A small change in the PA output or antenna efficiency is measurable.

It really comes down to what is the purpose of our experiments: being able to make CW contacts is a perfectly reasonable aim - please carry on. In my case it is to see just what is possible with minimalist (hardware) equipment on the VLF, LF and MF bands. Yes, I am gaining valuable dBs by the use of efficient coding systems and clever PC software, but I see nothing wrong in that.

And finally, please do NOT call me an appliance operator: all my VLF-MF equipment is home-made as is much of my HF and VHF gear. I am happy to use modern technology to enhance my enjoyment of the hobby and to exploit weak signal modes but I am equally happy to have a CW QSO on any band when the opportunity arises.

73s
Roger G3XBM



On 24 August 2011 18:48, mal hamilton <g3kevmal@talktalk.= net> wrote:
Jim take NOTE
Impulsive noise generates a random output that looks like a valid callsign so this is also inventing a signal that you imagine to exist.
An immediate positive ID, don't depend on it !!
An appliance communications operator is easily hoodwinked.
Bletchley Park CW  expert Radio Op= erators managed to piece messages together and achieved the object., and no doubt used imagination.
No expertise is need to send/receive wspr and for that matter a lot of other appliance operator modes, know in the services today as IDIOT PROOF comms black boxes.
For a commercial operator that needs to shift thousands of messages worldwide then automated digital modes are necessary and useful, but for a radio hobbyist its like using a sledge hammer to crack the proverbial nut
 
g3kev
 
 
 
 
 Original Message -----
Sent: Wednesday, August 24, 2011 6:06 PM
Subject: Re: LF: WSPR or QRSS: which is better?

I know what you're referring to.  In cases of impulsive noise, there is a finite probability of something eventually  = ;getting through the decoder and being flagged as valid.  The very nature of heavy source coding, means that the resulting random output will look like a valid callsign.   However, WE then apply the next level of e= rror detection, by knowing the combination must be rubbish.
 
'jnt   [and there is another example of source c= oding]


 
On 24 August 2011 17:47, Graham <g8fzk@g8fzk.fsne= t.co.uk> wrote:
>>  and gives absolutely guaranteed error free decoding, or nothing at all.  <<
 
Are you sure ? 
 
G..

Sent: Wednesday, August 24, 2011 5:12 PM
Subject: Re: LF: WSPR or QRSS: which is better?

WSPR works in a 1.46Hz signal bandwidth and because of its very high level of error correction and soft-decision decoding, means that it will work at a S/N of about 3dB in this bandwidth, and sometimes a bit lower still  (Normally, FSK with no correction at all needs about 10 - 12dB S/N for near error-free performance)
 
QRSS has to show about 6 - 10dB in its signal bandwidth to be able to discern fully what is sent, although a slightly lower S/N may be useable when you 'know' what you should be receiving.  (A form of forward error correction is now in use here as well perhaps :-) = ; So lets say 5dB S/N is a working value..
 
So take 3dB in 1.46Hz as a starting point and deriv= e the bandwidth for QRSS needed to get 5dB S/N with the same signal.  This will have to be narrower to get a 2dB higher S/N and works out as 1.46 / 10^(2/10) =3D 0.92Hz
 
So QRSS used with a 0.9Hz bandwidth - which I think means about a 2 - 3s dot period ought to be decoded at the same S/N as a WSPR signal.   Which is probably the info you wanted.
 
But now compare source coding efficiencies.   WSPR f= its a callsign, locator and power level into a 110 second transmission - and gives absolutely guaranteed error free decoding, or nothing at all.  About 12 characters in actuality, but that is being a bit un= fair as the coding forces certain callsign and locator formatting.   So= in all probablility, more like 7 or 8 effective characters (I'm being a bit empirical here)
 
Assuming standard QRSS - not DFCW - , which if like standard Morse, then 5 characters takes about 50 dot symbols to send (12WPM =3D 60 chars in 1 minute, =3D 1 char / second, or about 10 dot periods / second.    Dot speed =3D WPM / 1.2)   If we ha= ve 2s dots, that is 5 characters can be sent in the time for a WSPR transmission.
 
So as a quick estimate, WSPR wins by roughly 2dB in S/N terms for a given dot period / noise bandwidth.  And at similar S/N values, WSPR is about 1.5 times faster
Andy
 
 
 
 
On 24 August 2011 16:42, Roger Lapthorn <= ;roger= lapthorn@gmail.com> wrote:
A question for the coding experts here: WSPR is an excellent weak signal beaconing mode, but at what QRSS speed is QRSS "better" ?

73s
Roger G3XBM

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








--
ht= tp://g3xbm-qrp.blogspot.com/
http://www.g3xbm.c= o.uk
http://www.youtube.com/user/g3xbm
https://sites.google.com/site/sub9khz/






--
http://g3xbm-qrp.blog= spot.com/
http://www.g3xbm.co.uk
http://www.yout= ube.com/user/g3xbm
https= ://sites.google.com/site/sub9khz/

= --Apple-Mail-1-909826627--