Return-Path: Received: from mtain-dc11.r1000.mx.aol.com (mtain-dc11.r1000.mx.aol.com [172.29.64.139]) by air-mf06.mail.aol.com (v126.13) with ESMTP id MAILINMF063-8bef4b4a44be3cb; Sun, 10 Jan 2010 16:21:02 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-dc11.r1000.mx.aol.com (Internet Inbound) with ESMTP id 87179380000E0; Sun, 10 Jan 2010 16:21:00 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NU5Cc-0005du-PZ for rs_out_1@blacksheep.org; Sun, 10 Jan 2010 21:20:02 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NU5Cc-0005dl-1Z for rsgb_lf_group@blacksheep.org; Sun, 10 Jan 2010 21:20:02 +0000 Received: from mail-fx0-f217.google.com ([209.85.220.217]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NU5CZ-0004nF-W1 for rsgb_lf_group@blacksheep.org; Sun, 10 Jan 2010 21:20:02 +0000 Received: by fxm9 with SMTP id 9so18139530fxm.30 for ; Sun, 10 Jan 2010 13:19:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:content-type; bh=FAU/3XBv8Aogebk9PMMYCShQfP0k828Ewurq5HGCN3c=; b=YwP5Tmqfi1SjRnwWCQEMfvf9dPxprT+L4CPhwiKFb4WQw2Ix4wgJXns5xFcN/BAnZo zez6MpE6I2MYu0QsBew9J7PUoFdBBpFB/qbkCcBPfrh+amplLYHGIwHhf62TdULA1nTR huIh3Z4H9Jkcpw6ha2+pYrETJDk2RXvsPBQNE= DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=lV0/5kYv4lBftv7Co3eeCdclmUjC8Ce4S1UPRfN1EunJUIDtoB69mbaJe3tyxj7oSo El5RF2OhUkANLqcLgSCjYyQ+qwXoKLTROJ05eNg7TY6yZeCTLrFihOg75E469cL8NE2P 3IueyAJDeXt31YJzsKuTe8pFKEvLCqhXUpw8I= MIME-Version: 1.0 Received: by 10.239.142.10 with SMTP id e10mr28481hba.82.1263158393095; Sun, 10 Jan 2010 13:19:53 -0800 (PST) In-Reply-To: <9afca2641001101153u288ebc3dh81ba03efc09b650@mail.gmail.com> References: <000e01ca9223$6d16ec90$0517aac0@desktop> <9afca2641001101102r6252b153lf6d911ee622589e5@mail.gmail.com> <004101ca922b$214cf0e0$0401a8c0@xphd97xgq27nyf> <9afca2641001101153u288ebc3dh81ba03efc09b650@mail.gmail.com> Date: Sun, 10 Jan 2010 21:19:53 +0000 Message-ID: From: Andy Talbot To: rsgb_lf_group@blacksheep.org X-Karma: unknown: DomainKey-Status: good (testing) X-Spam-Score: 0.3 (/) X-Spam-Report: autolearn=disabled,HTML_FONT_BIG=0.256,HTML_MESSAGE=0.001 Subject: Re: LF: Link budget calculation or estimation of dist for given power on WSPR Content-Type: multipart/alternative; boundary=001485f95ffa50c872047cd5fbc4 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.0 required=5.0 tests=HTML_30_40, HTML_FONTCOLOR_UNKNOWN,HTML_FONT_BIG,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-sid: 3039ac1d408b4b4a44bc7619 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --001485f95ffa50c872047cd5fbc4 Content-Type: text/plain; charset=ISO-8859-1 Making comparisons between WSPR and QRSS should take into account the signalling rate, and it is only fair to compare like with like. A WSPR transmission carries a callsign, a locator and a power level. Approximately 12 characters worth of data, or in Morse code terms around 2.4 words which it sends in 2 minutes - hence about 1.2 WPM. If 12WPM beans 100ms dots, then this rate corresponds to a dot interval of 1 second. So for a fair comparison, you *must* compare WSPR with 1s QRS - which I believe is faster than most ops actually use. The version of Argo I have only goes down to 3s dots which infers 5dB bandwidth improvement immediately. So if, as I recall someone saying here, WSPR and 3s QRSS give similar decoding capability, then that immediately suggests WSPR is 5dB 'up' on QRSS, or QRSS takes three times longer for the same message. Its rather more complicated in reality, as this simple ccomparison assumes the QRS signal is copied with zero errors. As it involves fuzzy logic and human interpretation, we can probably say it contributes the error correction To compare data modes in noise, its best to use a normalised data rate expressed in Bits/second/Hz See http://www.g4jnt.com/MartleSham.htm where I come up with an empirically determined estimate that the WSJT modes, WSPR, JT4, etc give about 6dB enhancement in S/N vs. decoding than CW - when normalised for an equivalent signalling rate. Andy www.g4jnt.com This email has been scanned for damaging side-effects by the health and safety police, is guaranteed to contain no substances hazardous to health, but may contribute to dissolving the nether and polar regions 2010/1/10 Roger Lapthorn > Fair comment Mal, and one of these days I'll try QRS and see how it > performs. > > It should be possible to get a pretty good idea of the theoretical range > limit for WSPR on 500kHz based on required S/N (which can be as low as -30dB > for WSPR), path loss calculations, ERP etc.. I shall be interested to see > what "the experts" say. > > 73s > Roger G3XBM > > > > 2010/1/10 mal hamilton > >> Had u been on QRS CW he probably would have copied u since he saw ur >> trace. I often see traces that do not decode for some time but had the trace >> been keyed it could have been identified. >> I have been making this point for some time, avoid guesswork and >> speculation and use normal CW or QRS CW >> Regardless of erp transmitted the weakness is often at the RX end Little >> antenna Little signal Big antenna Big signal and environment regarding >> noise. >> RX loop antennas not optimised towards ur stn, these situations cannot be >> calculated just guessed and meaningless. >> Get into QSO mode and see how far u can get in real time. >> >> G3KEV >> >> >> ----- Original Message ----- >> *From:* Roger Lapthorn >> *To:* rsgb_lf_group@blacksheep.org >> *Sent:* Sunday, January 10, 2010 7:02 PM >> *Subject:* Re: LF: Link budget calculation or estimation of dist for >> given power on WSPR >> >> Certainly GM4SLV has a much lower noise floor than most stations on >> 500kHz Jim. I think he estimated about 10dB lower, so it may be easier for >> him to hear very weak signals than many others. >> >> For what it's worth, my 1mW ERP has been received at -18dB S/N at 990kms >> range in S.Germany (and at around -23dB a few times), so assuming another >> 10-12dB in hand, that must be good for another skywave "hop" under >> favourable conditions. I am still hopeful that TF3HZ might just spot me on a >> good night. The magic 1000kms barrier is tantalisingly close. RN3AGC says he >> might just have seen a "whisper" of a trace from me the other night and he >> is 2400kms away, but if it was me it was far too weak to decode. >> >> It will be interesting to see what people say is possible based on the >> propagation theory etc. >> >> 73s >> Roger G3XBM >> >> 2010/1/10 James Cowburn >> >>> Dear LF, >>> >>> Has anyone any ideas or suggestions on a resource for calculation of a >>> link budget for WSPR over a set distance? >>> >>> As it seems I can get up to GM4SLV reasonably consistently on my current >>> antenna/power setting with a SNR of around -22dB and the limit for WSPR is >>> around -30dB then is there a means for roughly estimating or indeed >>> accurately calculating the Expected Max Range (EMR) at that power setting >>> and antenna configuration? >>> >>> Clearly, there are differences between separate Rx stations but if one >>> knows the ratio between two or more Rx stations then it should be possible >>> to pro-rate or estimate at least the signal strength at a given Rx based on >>> its performance with other known signals. >>> >>> If I can do 916km with an SNR of say -22dB then how much further would >>> the remaining 8dB or so of WSPR detection get me, assuming the other Rx has >>> the same capability as GM4SLV and if their capability is different, then is >>> it fine to factor for the dB difference over known paths/signals? >>> >>> Thanks in advance for any answers or pointers and best wishes to all for >>> a great 2010 >>> >>> With best regards >>> >>> >>> >>> >>> >>> *Jim* >>> >>> >>> >>> >>> >>> Dr. James Cowburn G7NKS >>> >>> E james.cowburn@virgin.net >>> >>> ** >>> >>> >>> >> >> >> >> -- >> >> http://g3xbm-qrp.blogspot.com/ >> http://www.g3xbm.co.uk >> http://www.youtube.com/user/G3XBM >> G3XBM GQRP 1678 ISWL G11088 >> >> > > > -- > > http://g3xbm-qrp.blogspot.com/ > http://www.g3xbm.co.uk > http://www.youtube.com/user/G3XBM > G3XBM GQRP 1678 ISWL G11088 > --001485f95ffa50c872047cd5fbc4 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Making comparisons between WSPR and QRSS should take into account the= signalling rate, and it is only fair to compare like with like.
=A0
A WSPR transmission carries a callsign, a locator and a power level.= =A0 Approximately 12 characters worth of data, or in=A0Morse code=A0terms= =A0around 2.4 words which it sends in 2 minutes - hence about 1.2 WPM.=A0= =A0If 12WPM beans 100ms dots, then this rate corresponds to a dot interval= of=A01 second.=A0 So for a fair comparison, you must compare WSPR= with 1s QRS - which I believe is faster than most ops actually use.=A0=A0= The version of Argo I have only goes down to 3s dots which infers 5dB ban= dwidth improvement immediately.
=A0
So if, as I recall someone saying here, WSPR and 3s QRSS give similar= decoding capability, then that immediately suggests WSPR=A0is 5dB 'up= ' on QRSS, or QRSS takes three times longer for the same message.=A0= =A0
=A0
Its rather more complicated in reality,=A0 as this simple ccomparison= assumes the QRS signal is copied with zero errors. =A0As it involves fuzz= y logic and human interpretation, we can probably say=A0it contributes the= error correction
=A0
To compare data modes in noise, its best to use a normalised=A0data= rate expressed in Bits/second/Hz=A0
See http://www.g4jnt.= com/MartleSham.htm=A0where I come up with an empirically determined es= timate that the WSJT modes, WSPR, JT4, etc give about 6dB enhancement in= S/N vs. decoding than CW - when normalised for an equivalent signalling= rate.
=A0

Andy
www.g4jnt.= com

This email has been scanned for damaging side-effects by th= e health and safety police, is guaranteed to contain no substances hazardo= us to health, but may contribute to dissolving the nether and polar region= s


2010/1/10 Roger Lapthorn <= rogerlapthorn@gmail.com>=
Fair comment Mal, and one of= these days I'll try QRS and see how it performs.

It should be= possible to get a pretty good idea of the theoretical range limit for WSP= R on 500kHz based on required S/N (which can be as low as -30dB for WSPR),= path loss calculations, ERP etc.. I shall be interested to see what "= ;the experts" say.

73s
Roger G3XBM



2010/1/10 mal hamilton <g3kevmal@talktalk= .net>
Had u been on QRS CW he probably woul= d have copied u since he saw ur trace. I often see traces that do not deco= de for some time but had the trace been keyed it could have been identifie= d.
I have been making this point for som= e time, avoid guesswork and speculation and use normal=A0CW or QRS CW
Regardless of erp transmitted the wea= kness is often at the RX end Little antenna Little signal Big antenna Big= signal and environment regarding noise.
RX loop antennas not optimised toward= s ur stn, these situations cannot be calculated just guessed and meaningle= ss.
Get into QSO mode and see how far u= can get in real time.
=A0
G3KEV
=A0
----- Original Message -----
Sent: Sunday, January 10, 2010 7:02 PM
Subject: Re: LF: Link budget calculation or estimation of dist= for given power on WSPR

Certainly GM4SLV has a much lower noise floor than most stations on= 500kHz Jim. I think he estimated about 10dB lower, so it may be easier fo= r him to hear very weak signals than many others.

For what it's= worth, my 1mW ERP has been received at -18dB S/N at 990kms range in S.Ger= many (and at around -23dB a few times), so assuming another 10-12dB in han= d, that must be good for another skywave "hop" under favourable= conditions. I am still hopeful that TF3HZ might just spot me on a good ni= ght. The magic 1000kms barrier is tantalisingly close. RN3AGC says he migh= t just have seen a "whisper" of a trace from me the other night= and he is 2400kms away, but if it was me it was far too weak to decode.
It will be interesting to see what people say is possible based on the= propagation theory etc.

73s
Roger G3XBM

2010/1/10 James Cowburn <<= a href=3D"mailto:james.cowburn@virgin.net" target=3D"_blank">james.cowburn= @virgin.net>

=A0Dear LF,

Has anyone any ideas or suggestions on a resource= for calculation of a link budget for WSPR over a set distance?

As it seems I can get up to GM4SLV reasonably consi= stently on my current antenna/power setting with a SNR of around -22dB and= the limit for WSPR is around -30dB then is there a means for roughly esti= mating or indeed accurately calculating the Expected Max Range (EMR) at th= at power setting and antenna configuration?

Clearly, there are differences between separate Rx= stations but if one knows the ratio between two or more Rx stations then= it should be possible to pro-rate or estimate at least the signal strengt= h at a given Rx based on its performance with other known signals.<= /font>

If I can do 916km with an SNR of say -22dB then how= much further would the remaining =A08dB or so of WSPR detection get me,= assuming the other Rx has the same capability as GM4SLV and if their capa= bility is different, then is it fine to factor for the dB difference over= known paths/signals?

Thanks in advance for any answers or pointers and= best wishes to all for a great 2010

With best reg= ards=

=A0

=A0

Jim

=A0

=A0

Dr. James Cow= burn G7NKS

E= james.cowburn@virgin.net<= /span>= =

=A0

=A0




--

http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.= uk
= http://www.youtube.com/user/G3XBM
G3XBM =A0 =A0GQRP 1678 =A0 =A0 = =A0ISWL G11088

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