From: "James Cowburn" <james.cowburn@virgin.net>
To: <rsgb_lf_group@blacksheep.org>
References: <8E070AD22619484C9E2D22046F45C521@JimPC> <4AA224DE.17607.C34F15@dave.davesergeant.com>
Date: Sat, 5 Sep 2009 10:24:09 +0100
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Subject: LF: RE: Re: WSPR beacon
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Hi Dave

Clock synchronization is key to WSPR, anything much more than 1 second out
between you and the other station will result in no decodes (been there done
that!)despite bold traces on the waterfall.  Also the WSPR program only
covers some 200Hz so unless the frequency is within that block it won't pick
it up.  

I use a little routine that continually links my pc clock to a time server
and updates every 30 mins as my pc clock drifts like mad esp when the cpu is
busy.  I gather you may already be doing this so I'm probably teaching
granny to suck eggs!

HTH


With best regards
 
 
Jim
 
 
-----Original Message-----
From: owner-rsgb_lf_group@blacksheep.org
[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Dave Sergeant
Sent: 05 September 2009 09:44
To: rsgb_lf_group@blacksheep.org
Subject: LF: Re: WSPR beacon

On 4 Sep 2009 at 21:48, James Moritz wrote:

> Dear LF Group,
> 
> The M0BMU WSPR beacon is running again tonight 0n 503.975kHz (502.4k
> "dial frequency"). Any reports are very welcome. Also a very strong
> signal from SM6BHZ tonight.
> 
> Cheers, Jim Moritz
> 73 de M0BMU 
> 
> 

Well prompted by all the mails on here I have just installed the WSPR 
software and had a listen to your signals this morning.

I noticed a couple of things which might explain why I was not getting 
any decodes:

1. On switch on of my K2 and Datong UC1 which I use for 500kHz receive 
there is a noticeable drift, initially as high as 10Hz in the 2 minute 
sampling period but eventually dropping to within 1Hz. I could not find 
a spec as to how stable the receiver needs to be for WSPR. I believe 
most of this drift is the 116MHz downconverter crystal in the UC1, 
which is a big limitation to using it as a serious 500kHz receiver.
2. Although I synchronised my computer clock to the time standards, and 
it seems just a fraction of a second different from my 60kHz clock, 
your transmissions seemed to be starting a second or two early, before 
my WSPR started receiving, and finishing at around the 1.52 minutes 
point. Is your clock out, or is this how it is supposed to work?
3. You are of course s9+ at this range, and show as bright red on 
WSPR's spectrogram. Hardly 'weak signal'. Does the software cope with 
strong signals or does it overload?

The only decode I got was for 'C1N/NU0RWS' in one of your non-transmit 
periods. With things like that coming out of white noise it doesn't 
give me much confidence in some of the other things the WSPR folks are 
bragging about....

It does though work OK on 30m and I have decoded a few Eu stations so I 
would have thought I would have been able to copy Jim.

I guess this will be another few days little play before I go back to 
more useful things...

73 Dave G3YMC


I have received a few Eu stations on 30m
http://www.davesergeant.com