Dear Graham, LF Group,
Thanks for our first QSO this evening. As keyboard-to-keyboard "chat" modes
go, this has to be the best I have experienced so far at LF/MF. The 32
tone/1kHz sub-mode produced almost 100% copy provided the signal was
audible - the somewhat slower 4 tone/250Hz setting was better still, only
producing errors during short periods at the fading minima when the signal
was completely inaudible and invisible on the spectrogram as well. I have
always struggled to copy G0NDB before, but on this occasion we had a fairly
lengthy QSO without any great difficulty. I think the main practical
difficulty for random QSOs would be knowing that there was a signal present
to decode - it would be sensible to have a calling frequency for future
tests.
I would agree that the 1kHz bandwidth sub-mode is too wide for routine use
in the present 500kHz band. But it does not violate the present licence
conditions, and I think it is an interesting experiment to see if a
relatively wide-band mode is an advantage for selective fading conditions on
this band. Looking at the various menus in Fldigi, I see that Olivia can be
configured for any combination of bandwidth from 125Hz to 2kHz, and 2 - 256
tones (I tried it - you can have 256 tones and 125Hz, or 2 tones in 2kHz,
although how well it works is another matter...). It would be interesting to
try back-to-back comparisons with varying parameters to test the
possibilities of fast vs. slow, wide vs. narrow.
Cheers, Jim moritz
73 de M0BMU
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