Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-df05.r1000.mx.aol.com (Internet Inbound) with ESMTP id B033C380001C7; Wed, 24 Aug 2011 14:57:28 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1QwIcg-0008Sa-9d for rs_out_1@blacksheep.org; Wed, 24 Aug 2011 19:56:22 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1QwIcf-0008SR-AU for rsgb_lf_group@blacksheep.org; Wed, 24 Aug 2011 19:56:21 +0100 Received: from mail-gw0-f43.google.com ([74.125.83.43]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1QwIcd-0006m4-BQ for rsgb_lf_group@blacksheep.org; Wed, 24 Aug 2011 19:56:21 +0100 Received: by gwm11 with SMTP id 11so546358gwm.16 for ; Wed, 24 Aug 2011 11:56:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=r7lcJxo3sVndqqzjrug6wA7YJcJoZIhASmeT9t2+1fQ=; b=IxSVXfo2T03u5G6JNJFJgmnlvFMp/bxb5HJsWMwotGuGVAxPQeaj7c6nYaz0qMFWDg Q7oq3baPYv4/DL+K6F3msfhQIEsz4zh8YL1zDEzyVmD7VckAsNVDRrwwLkLFAkiMgJ5D 5AN0RLO1/8cJVKjO25twIIuZuteFzZrStdBMQ= MIME-Version: 1.0 Received: by 10.143.68.20 with SMTP id v20mr2885345wfk.325.1314212172239; Wed, 24 Aug 2011 11:56:12 -0700 (PDT) Received: by 10.142.188.7 with HTTP; Wed, 24 Aug 2011 11:56:12 -0700 (PDT) In-Reply-To: <1314211001.22166.YahooMailNeo@web125716.mail.ne1.yahoo.com> References: <790E5582101F4A069156B4677843CD78@AGB> <007f01cc6286$0f541490$0401a8c0@xphd97xgq27nyf> <1314211001.22166.YahooMailNeo@web125716.mail.ne1.yahoo.com> Date: Wed, 24 Aug 2011 19:56:12 +0100 Message-ID: From: Roger Lapthorn To: rsgb_lf_group@blacksheep.org 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=000e0cd2a0d2af933604ab44dd3c X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.6 required=5.0 tests=HTML_20_30, HTML_FONTCOLOR_UNSAFE,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-SCORE: 0:2:472387200:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d006.1 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d40d94e5549987d3c X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --000e0cd2a0d2af933604ab44dd3c Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable 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 websitefor 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 o= n 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 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 > 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 > *Para:* rsgb_lf_group@blacksheep.org > *Enviado:* mi=E9rcoles, 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 lik= e > 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 i= s > measurable. > > 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 m= y > case it is to see just what is possible with minimalist (hardware) equipm= ent > 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 us= e > modern technology to enhance my enjoyment of the hobby and to exploit wea= k > 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 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 > 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 ----- > > *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? > > I know what you're referring to. In cases of impulsive noise, there is a > finite probability of something eventually getting through the decoder a= nd > being flagged as valid. The very nature of heavy source coding, means th= at > the resulting random output will look like a valid callsign. However, W= E > then apply the next level of error detection, by knowing the combination > must be rubbish. > > 'jnt [and there is another example of source coding] > > > > On 24 August 2011 17:47, Graham wrote: > > ** > >> and gives absolutely guaranteed error free decoding, or nothing at > all. << > > Are you sure ? > > G.. > > *From:* Andy Talbot > *Sent:* Wednesday, August 24, 2011 5:12 PM > *To:* rsgb_lf_group@blacksheep.org > *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 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 > > 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 fits a callsign, locat= or > and power level into a 110 second transmission - and gives absolutely > guaranteed error free decoding, or nothing at all. About 12 characters i= n > actuality, but that is being a bit unfair 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 mi= nute, > =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 f= or > 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 > www.g4jnt.com > > > > > On 24 August 2011 16:42, Roger Lapthorn 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://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/ > > > > --=20 http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/g3xbm https://sites.google.com/site/sub9khz/ --000e0cd2a0d2af933604ab44dd3c Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Hi Marcelino

Thanks for this.

Yes I understand fully what is= needed for LF/MF WSPR and have implemented simple and low cost WSPR soluti= ons 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 sim= ple 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 improve= ments 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 ea= rs and good system and antennas.

73s
Roger G3XBM



On 24 Augu= st 2011 19:36, Marcelino Garcia <lu7dsu@yahoo.com.ar> wrote:
Roger,
=
=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 I fully agree with your statem= ents, but I'm afraid that with a minimalist home made CW transmitter, l= et's say just a one transistor xtal oscillator, it's not=A0 possibl= e to use WSPR, for this mode a little more complex transmitter, may be SDR = based, should be used.
73,
Marcelino - LU7DSU

De: Roger Lapthorn <rogerlapthorn@gmail.com>
Para: rsgb_lf_group@blacksheep.org
Enviado: mi=E9rcoles, 24 de = agosto de 2011 15:18
Asunto:<= /b> Re: LF: WSPR or QRSS: which is better?

Mal

Thanks again for your comments, some of which are valid= .=A0

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

As I have said countless times no= w, no other mode apart from WSPR that I know of is able to give me almost i= nstant feedback (via the internet database) at a distance that (a) my signa= l is being received at all, (b) how far it is getting, and (c) how strong i= t 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 o= r antenna efficiency is measurable.

It really comes down to what is the purpose of our experiments: being a= ble 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) equi= pment on the VLF, LF and MF bands. Yes, I am gaining valuable dBs by the us= e of efficient coding systems and clever PC software, but I see nothing wro= ng 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 ham= ilton <g3kevmal@talktalk.net> wrote:
Jim take NOTE
Impulsive noise generates a random output that lo= oks like=20 a valid callsign so this is also=A0inventing a signal that you imagine to= =20 exist.
An immediate positive ID, don't depend on it= =20 !!
An appliance communications operator is easily=20 hoodwinked.
Bletchley Park CW=A0=A0expert Radio Operators=20 managed to piece messages together and achieved the object., and no doubt u= sed=20 imagination.
No expertise is need to send/receive wspr and for= that=20 matter a lot of other appliance operator modes, know in the services today = as=20 IDIOT PROOF comms black=A0boxes.
For a commercial operator that needs to shift tho= usands of=20 messages worldwide then automated digital modes are necessary and useful, b= ut=20 for a radio hobbyist its like using a sledge hammer to crack the proverbial= =20 nut
=A0
g3kev
=A0
=A0
=A0
=A0
=A0Original Message -----
From:=20 Andy=20 Talbot
Sent: Wednesday, August 24, 2= 011 6:06=20 PM
Subject: Re: LF: WSPR or QRSS: whic= h is=20 better?

I know what you're referring to.=A0 In cases of impulsive noise,= there=20 is a finite=A0probability of=A0something eventually =A0getting=20 through the decoder and being flagged as valid.=A0 The very nature of hea= vy=20 source coding, means that the resulting random output will look like a va= lid=20 callsign.=A0=A0 However, WE then apply the next level of error=20 detection, by knowing the combination must be rubbish.
=A0
'jnt=A0=A0 [and there is another=A0example of source=20 coding]


=A0
On 24 August 2011 17:47, Graham <g8fzk@g8fzk= .fsnet.co.uk>=20 wrote:
>>=A0 and gives absolutely guaranteed error free decoding, o= r=20 nothing at all.=A0 <<
=A0
Are you sure ?=A0
=A0
G..

Sent: Wednesday, August 24, 2011 5:12 PM
Subject: Re: LF: WSPR or QRSS: which is=20 better?

WSPR works=A0in a 1.46Hz signal bandwidth and because of its very= =20 high level of error correction and soft-decision decoding, means=20 that=A0it will work at a S/N of about 3dB in this bandwidth, and=20 sometimes a bit lower still=A0 (Normally, FSK with no correction at=20 all=A0needs about 10 - 12dB S/N for near error-free performance)
=A0
QRSS=A0has to show about 6 - 10dB in its signal bandwidth to be ab= le=20 to discern fully what is sent, although a slightly lower S/N may be use= able=20 when you 'know' what you should be receiving.=A0 (A form of for= ward error=20 correction is now in use here as well perhaps=A0:-)=A0 So lets say 5dB= =20 S/N is a working value..
=A0
So take=A03dB in 1.46Hz=A0as a starting point and derive the=20 bandwidth for QRSS needed to get 5dB S/N with the same signal.=A0 This= =20 will have to be narrower to get a 2dB higher S/N and works out as=20 1.46=A0/ 10^(2/10) =3D 0.92Hz
=A0
So QRSS used with a 0.9Hz bandwidth - which I think means about a = 2 -=20 3s dot period ought to be decoded at the same S/N as a WSPR=20 signal.=A0=A0 Which is probably the info you wanted.
=A0
But now compare source coding efficiencies.=A0=A0 WSPR fits a=20 callsign, locator and power level into a 110 second transmission - and = gives=20 absolutely guaranteed error free decoding, or nothing at=20 all.=A0=A0About 12 characters in actuality, but that is being a bit=20 unfair as the coding forces certain callsign and locator=20 formatting.=A0=A0 So in all probablility, more like 7 or 8 effective=20 characters (I'm being a bit empirical here)
=A0
Assuming standard QRSS - not DFCW - , which if like standard Morse= ,=20 then 5 characters takes about 50 dot symbols to send (12WPM =3D 60 char= s in 1=20 minute, =3D 1 char / second, or about 10 dot periods /=20 second.=A0=A0=A0 Dot speed =3D WPM / 1.2) =A0 If we have 2s dots,=20 that is 5 characters can be sent=A0in the time for a WSPR=20 transmission.
=A0
So as a quick estimate, WSPR wins by=A0roughly 2dB in S/N terms fo= r=20 a given dot period / noise bandwidth.=A0 And at similar S/N values, WSP= R=20 is about 1.5 times faster
Andy
=A0
=A0
=A0
=A0
On 24 August 2011 16:42, Roger Lapthorn <r= ogerlapthorn@gmail.com> wrote:
A=20 question for the coding experts here: WSPR is an excellent weak signa= l=20 beaconing mode, but at what QRSS speed is QRSS "better"=20 ?

73s
Roger G3XBM
=
--
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk<= br> http://www.youtube.com/user/g3xbm
https://sites.goo= gle.com/site/sub9khz/








--
http://g3xbm-qrp.blo= gspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
https://sites.goo= gle.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/

--000e0cd2a0d2af933604ab44dd3c--