Message-ID: <000401c521ae$640c9720$6507a8c0@Main>
From: "Alan Melia" <Alan.Melia@btinternet.com>
To: rsgb_lf_group@blacksheep.org
References: <4229F14D.12369.DB4AB1@localhost>
Date: Sat, 5 Mar 2005 18:08:07 -0000
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Subject: LF: Re: Slow mode comparisons
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Hi Mike, Mmmm I think it might be "horses for courses" on this one. I
suspect it would depend mainly on the type of noise. I am finding that for
instance John WD2XES and Warren WD2XGJ are transmitting close to one another
and are only about 30 miles apart, so the fading is similar. With lots of
snow on the 30sec slow ARGO screen John is easier to decode with DFCW  than
Warren (QRSS) whose gaps are often filled by the "snow". Certainly the
"slope" of ARGO detection is very steep. I have done some local tests and I
estimate that, with normal band noise, there is only a 3dB difference in
signal level needed to go between "T" and "O". The swap from QRSS3 to QRSS10
is an advantage of about 3dB also. It does point to picking the right mode
for the path, and the conditions.

Cheers de Alan G3NYK

----- Original Message -----
From: "Mike Dennison" <mike.dennison@ntlworld.com>
To: <rsgb_lf_group@blacksheep.org>
Sent: 05 March 2005 17:50
Subject: LF: Slow mode comparisons


> This morning, I worked a new station for me (No:103), DL3ZID. He
> first called me on DFCW3, but was impossible to read. He then changed
> to QRSS3 which was an improvement, but not 100%. A change to QRSS10
> gave a really clear easy-to-read signal. I took screenshots which are
> on my web site, and these clearly show the difference between the
> three modes. With marginal signals, I believe that DFCW is slightly
> poorer than QRSS at the same dot length, because of the added
> complication of the two frequencies, each of which may have QRM that
> might be a 'dot'.
>
> I think this may be the first time that these three modes have been
> compared in this way with a 'live' marginal signal. If DL3ZID reads
> this reflector, my thanks for the QSO and for the opportunity for
> this comparison.
>
> See the pics at:
> http://lf.apersonalguide.co.uk
>
> Mike, G3XDV
> ===========
>
>
>
>