[pskmail] Re: Test Alpha Fldigi version for FM (VHF/UHF) links
- From: John Douyere <vk2eta@xxxxxxxxx>
- To: pskmail@xxxxxxxxxxxxx
- Date: Wed, 21 Mar 2012 22:20:15 +1100
Hi Larry,
Thank you for the feedback. Keep us informed of the results please.
73, John
On 21/03/2012 10:12 PM, "Larry Levesque" <ka1vgm@xxxxxxxxx> wrote:
> Thanks for the tips.
>
> It is running fine on my Ubuntu 10.04 machines.
>
> I will be doing some testing over VHF simplex in the next week or so.
>
> I just sent a 30k file in under 2 minutes. Wow!!
>
>
>
> On Wed, Mar 21, 2012 at 09:59:00PM +1100, John Douyere wrote:
> > Some extra information regarding the usage of the new modes in FM.
> >
> > In my test I have noticed that it is easy to overload the TX audio and
> > start loosing decoding accuracy on the other side.
> >
> > Since the ALC level is not related to the audio level in FM, the
> indicator
> > I use is the Modulation level (FT-8x7 series).
> >
> > As an example I found that having the modulation indication at about 1/3
> of
> > the maximum for a single carrier PSK is about right, giving a reasonable
> > audio level but no visible distortion.
> >
> > The multi-carrier modes can be a trap since the average level is lower
> than
> > a single PSK carrier modulation but the peaks are the same. So it sound
> > lower but the level must not be increased to compensate, otherwise the
> > peaks get truncated and the decoding suffer too.
> >
> > In SSB, the multi carrier PSK modulations will result in an average power
> > well below that of the single carrier PSK, but again we should not try to
> > compensate for it.
> >
> > Under these modulations, if you push the TX audio level ALC too high you
> > actually may well be getting only 20% of the max RIG power at the output,
> > with the ALC way up.
> >
> > Hope this helps,
> >
> > 73, John
>
> --
> Larry Levesque
> www.surrycomputerservices.com
>
>
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