Date: Fri, 2 Jan 2009 08:32:43 +0000
From: John P-G <gm4slv@sighthound.demon.co.uk>
To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: NON MORSE
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On Thu, 1 Jan 2009 16:35:53 -0000
"mal hamilton" <g3kevmal@talktalk.net> wrote:

> I have been looking around the various HF bands for NON MORSE acty
> and find  that the old RTTY is the most prolific mode in use

Mal,

You are, of course, entirely wrong in this assumption/observation.

Just because your ears identify RTTY easily doesn't mean that's the most
common mode. 

When you tune across 14.070MHz during the day how many PSK31 signals do
you think you hear? One, two?

I've just counted 15, at 0816 on a dark winter's morning, without
spending too long watching the band. There were probably many more
stations active, had I watched for longer.

How many RTTY stations did you spot? I saw and heard 2, in the same
time span that I counted 15 PSK stations.

So that seems to, in an unscientific way, disprove your theory.


How many Olivia / MFSK16  signals did you hear? None? Doesn't mean there
aren't active QSOs going on, just because your cursory sweep didn't
detect them - as I and others have pointed out, some of these modes are
so sensitive that they work well below the noise floor.

CW is a great mode, my favourite and the one that makes up 80% of my
QSO count, but the facts remain - some of the new DSP modes are more
sensitive, and if well designed, will work with a wide variety of
ionospheric/path disturbances (selective fading, multipath, group delay
errors, inband carrier QRM etc etc) as well or better than plain old CW.

I've done tests on 160m with a station in OH-land comparing
SSB/Hell/CW/MFSK16 and Olivia. 

Obviously the SSB was the poorest performer, but by far the
best, for readability of information was Olivia/MFSK. 
100% copy down to below 1W, long after the Hell and CW signals had been
lost. 

The CW performed very well in comparison to the SBB and Hell, and in
quick bursts could pass the rudiments of a QSO between QSB dips etc,
but the Olivia and MFSK modes just kept on printing, even though the
signals were inaudible and invisible on the waterfall.  You, scanning
the band looking for data for your survey, might not have even know we
were having a 100% copy QSO had you tuned across us that night.

Perhaps QRSS may have worked, with careful optimising of the
waterfall bandwidth etc, but that's hardly a fast, chatty, "pass
information" operating mode.

John