Message-ID: <199911130021.LAA10129@mailman.zeta.org.au>
From: "Steve Olney" <ollaneg@zeta.org.au>
To: rsgb_lf_group@blacksheep.org
Subject: LF: Re: visual-CW
Date: Sat, 13 Nov 1999 11:13:25 +1100
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G'day Rik,

I can indeed confirm that this slow visual CW works.  It was one of my
early attempts to figure out a way of improving the S/N on LF paths.  It
had one tone for the "dots" and one for the "dashes" spaced by 10Hz each
lasting for 30 seconds which were fed to an SSB transmitter.  The only
difference I had was that I sent a middle tone for the spaces between
characters and words.  I found that it was easier to determine the presence
of a carrier rather than an absence for a space and to actually separate
each "dot" or "dash" with a space tone.  This method is slower than the
method you suggest by a factor of about two. This middle space (or idle)
frequency also is an aid for tuning and gives a base line for the "dots"
and "dashes".   I had 1000Hz for the space (or idle) 1005Hz for the "dash"
and 995Hz for the "dot".   What are your comments on this?

The software didn't have a morse code generator, just random "dots",
"dashes" and spaces between them to test the method.   However, I got bound
up with my FDK method and in the process of developing the code for FDK, I
cut this slow FSK code out and I will have to rework it in the future to
get it back.

BTW, while tests have shown that FDK is better than PSK31 by about 17dB and
better than about 10dB better than a reasonable speed QRSS,  I feel that
the slowness of data transmission (one character/minute) and the stability
required (about 0.02Hz over one minute) will mean that FDK will not be
practical or attractive for nobody but the most dedicated.  In other words,
not enough gain for the pain.  It also requires synchronisation of the PCs
at both ends to within +/-10 seconds and has a fixed data rate of one
character/minute.

So all in all,  I will still play with FDK and prove it works over long
paths, but I will probably drift back to the slow FSK CW method and develop
it more.   The good thing is that everybody can use it and the speed can be
adjusted to suit the conditions as you have indicated, unlike FDK.

You obviously have progressed further than anyone else along this path and
as a user of your excellent QRSS program I (as well as others) was
wondering if you have developed your software to a point where you can let
others have a go?   I haven't worked out how to drive the soundblaster
directly from data in memory (I'm not clever enough to do that yet) so the
quickest my software could output the tones is practically every 15 seconds
or so.  You obviously have solved that problem or do you actually shift the
frequency of the carrier?

Anyway, this post is already too long, but I'm sure there are many of us
eager to try out your program and this great idea.

73s Steve Olney (VK2ZTO/AXSO - QF56IK : Lat -33 34 07, Long +150 44 40)
=============================================
LowFer URL:
http://www.zeta.org.au/~ollaneg/lowfer.htm
AXSO LF Experimental Station URL:
http://www.zeta.org.au/~ollaneg/axsoextx.htm
LF Receiving - FRG-100, CHA antenna
LF Transmitting - 177.5/177.4kHz 8W - 7.6m vertical or CHA
Modes - AM, SSB, PSK31, SSTV, Hellschreiber, QRSS
and a new experimental mode - FDK.  See this URL for more:
http://www.zeta.org.au/~ollaneg/FDK.htm
=============================================