Message-ID: <968580D3316847DF800B8C626C1AFE12@AGB>
From: "Graham" <g8fzk@g8fzk.fsnet.co.uk>
To: <rsgb_lf_group@blacksheep.org>
References: <001201c96d29$7ec00550$a402a8c0@Inspiron> <74D73520414D46898D59598D727BFB0E@AGB> <7C234838C15E4E18A6A7374FA2C5C592@JimPC>
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Date: Sat, 3 Jan 2009 12:57:06 -0000
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Subject: Re: LF: Re: Olivia QSO
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Hi Jim

I tended to  see a better print from the wider system, but the propagation 
changed over the test, your original signal was quite audible from the loud 
speaker, in fact , would of been enough for a ssb contact !. both systems 
appeared to  print into the noise , this is a unnerving feature of the mode 
,  clear type from nowhere !

I'm not sure on the tone v bandwidth pay off, but a email to the code group 
may get a outline ?

Simon Brown's  drm780  has in the olivia mode a layered software search, 
that when enabled, array processes the recovered audio file and detects an 
olivia signal, giving the frequency offset and will apply this to  the tx . 
I'm not sure if it will detect the mode but may well do.

Best would test would to  simply run the two systems in parallel as the peak 
power required is not high to  ensure reasonable decodes /

Interesting night !

Graham,..

--------------------------------------------------
From: "James Moritz" <james.moritz@btopenworld.com>
Sent: Saturday, January 03, 2009 1:36 AM
To: <rsgb_lf_group@blacksheep.org>
Subject: LF: Re: Olivia QSO

>
> 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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