Message-ID: <011801c968f3$a64c4e10$0301a8c0@mal769a60aa920>
From: "mal hamilton" <g3kevmal@talktalk.net>
To: <rsgb_lf_group@blacksheep.org>
References: <4956BFEE.19110.2EE6D21@v.d.heide.on-line.de> <001601c968e6$912297e0$4201a8c0@home>
Date: Sun, 28 Dec 2008 13:53:22 -0000
MIME-Version: 1.0
Subject: LF: Re: Re: WSPR and CW
Content-Type: text/plain;
	format=flowed;
	charset="iso-8859-1";
	reply-type=original
Content-Transfer-Encoding: 7bit
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org



----- Original Message ----- 
From: "James Moritz" <james.moritz@btopenworld.com>
To: <rsgb_lf_group@blacksheep.org>
Sent: Sunday, December 28, 2008 12:19 PM
Subject: LF: Re: WSPR and CW


> Dear Klaus, Laurence, LF Group,
>
> I have been doing some experiments with WSPR on 2 PCs linked by audio
> cables. I would certainly agree with KL1X about the importance of clock
> accuracy - I found that an error of 5 seconds was enough to completely
> prevent decoding. Fortunately, the clock on my shack PC is accurate enough
> that setting it against an MSF-controlled clock once every several hours 
> is
> OK.  I also found that the "QSO version" of WSPR in WSJT 7 and the WSPR 
> 1.01
> beacon software will correctly decode each other's signals, although in
> either case the QSO mode requires reception of all the overs of the QSO in
> order to display the callsigns, due to the format used. When using the
> beacon software for reception, be aware that it may take some minutes for
> the decode to appear after the signal has been received - this seems to be
> due to the "off line" nature of the signal processing used.
>
> Recent experience here is that the WSPR mode offers advantages compared to
> CW, either manual or QRSS, on the 500kHz band due to the low SNR and the
> fading experienced. Many signals are either always below the audible 
> noise,
> or not audible for long enough for aural CW copy without large numbers of
> repeats. With QRSS, and a sufficiently long dot period, one can indeed
> detect very weak signals, but the fading often prevents receiving, for
> example, a complete callsign without losing some symbols and so also
> requiring repeats. QRSS works much better on 136k, where the fading period
> is much longer.
>
> WSPR certainly decodes signals that are too weak for aural reception. In
> sensitivity terms, I think it is comparable to QRSS 3. WSPR has the
> advantage over QRSS 3 that the message duration is shorter. The 2 minute
> transmission period of WSPR is a reasonable match to the fading period
> experienced on 500kHz, so there is a good chance of sending the message
> successfully before the signal fades out.
JIM
YOU OBVIOUSLY HAVE NOT SEEN MY REPORTS RECENTLY.
I OFTEN COPY THE USA STATIONS AUDIBLE AND LOUD ON CW AS WELL AS THE QRS3 
TRANSMSSIONS.
WHEN YOU WERE STRUGGLING A FEW NIGHTS AGO ON WSPR I WAS SEEING THE SIGNAL 
TRACE SOLID INSPITE OF SOME SLOW QSB AND HAD XGR/2 BEEN ON QRS3 I CERTAINLY 
COULD HAVE HAD A QSO AS I DID A COUPLE OF NIGHTS LATER, XGR/2 OOO COPY.
This is the situation at my QTH obviously your RX set up needs tweaking. An 
other disadvantage of wspr is the accurate time sync required for a decode 
plus frequency accuracy, NOT the case with ON/OFF keyed morse slow or fast. 
All things considered there is nothing to date to beat CW in its many 
formats.
On the HF bands I have noticed an increase in hand sent and auto CW 
commercial acty, CW is certainly not going away, and during contests on the 
amateur bands one can hardly find a slot to TX.
There are digital modes also about but they seem to be slow at overtaking 
CW, most are obviously not convinced.
mal/g3lev






 I have yet to see any readable
> trans-atlantic CW or QRSS signals at this QTH, while copy of WE2XGR//2 
> using
> WSPR was reasonably consistent, producing a decode for about 25% of the
> transmissions. The redundancy in the data should also make WSPR relatively
> resistant to errors caused by QRN impulses, although the QRN level has 
> been
> low here recently. For beacon purposes, WSPR also has the huge advantage
> that reception, logging and reporting is automated, so the operator can go
> to bed sometimes!
>
> While WSPR does work well, I don't think it is the final word in LF/MF
> digital modes - In particular, the information in a QSO is largely
> restricted to "rubber stamp" exchanges. So I will certainly be interested 
> in
> trying other modes, and look forward to see the results of Klaus' work.
>
> Cheers, Jim Moritz
> 73 de M0BMU
>
>
>
>
>
>


--------------------------------------------------------------------------------



No virus found in this incoming message.
Checked by AVG - http://www.avg.com
Version: 8.0.176 / Virus Database: 270.10.0/1866 - Release Date: 12/27/2008 
8:49 PM