[arm-allstar] How to adjust the audio characteristics for both TX and RX?

[Irvin Fontanes]

Dave,

Thank you for the info. It would be great if we could manually tune the
digital filters :D

The audio from the fr6000's speaker sounds good....there is an AF OUT pin
on the back of the db25 and, if I recall correctly, there was no audio
coming out of that pin so I opted to use the DISC OUT pin (flat audio -
which I always prefer to use).....well, now that I'm thinking more about
the matter I believe there was/is no audio coming out of that pin because I
had set the min AF OUT value to "0" in the programming software which
effectively disabled anything coming out of the AF OUT pin.

Let me try that first.

Regards,
Irvin

On Thu, Nov 30, 2017 at 2:42 PM, David McGough <kb4fxc at inttek.net> wrote:

>
> Hi Irv,
>
> The simpleusb (or usbradio) preemphasis (hi pass) and deemphasis (lo pass)
> settings adjust IIR digital filters in the channel driver code. These
> filters have static, compiled-in coefficients, so there is no way to
> adjust them other than just enabling or disabling them.
>
> Your IDAS system has "speaker" audio input and output, so, you will
> probably want to leave preemphasis=no and deemphasis=no on the AllStar
> side.
>
> Some digital radios have audio equalization settings which can be tweaked
> a bit. I don't know if the ICOM radios have this capability. I know
> various DMR radios can be tweaked via the RSS software.
>
> I don't expect you'll gain very much by trying to equalize the audio AFTER
> it has passed thru the AMBE+2 low-bandwidth CODEC used by most digital
> radios (like IDAS). The best plan is to try to adjust the settings in the
> radio proper....That, or go back to analog FM, which will comparatively
> sound fantastic!
>
> 73, David McGough
>
>
>
>
> On Thu, 30 Nov 2017, "Irvin Fontanes via arm-allstar" wrote:
>
> > Doug,
> >
> > This is a private node. Just me as a user. It is used as follows:
> >
> > -Rpi 3 connected to an arcom rc-210 on port 2
> > -icom fr-6000 on port 1 running idas 6.25 khz bw
> >
> > The setup is configured so that I talk into the fr6000 with an icom
> > ic-f4261dt and it gets piped (in analog from the back of the db25) out to
> > my other private node.
> >
> > I know that the audio quality takes a toll when digitized and there's
> > nothing I can do about it; however; I'd like to experiment with whatever
> > code/script is called out when preemphasis=yes or no and deemphasis=yes
> or
> > no is selected since when the audio gets converted back to analog (out of
> > the fr6000's db25) it is missing some of the"highs".
> >
> > So, could someone tell me which script is called out when preemphasis=yes
> > or no and deemphasis=yes or no is selected? I would seriously like to
> > experiment.
> >
> > Thanks,
> > Irvin
> >
> > Irv,
> >
> >  Pre and de-emphasis is a fixed equalization designed around FM
> > communications standards. You cannot nor should you change that. Also
> using
> > pre or de-emphasis just to tailor audio is not a good idea. It should be
> > set correctly for the radio you  are using. There is currently no
> > equalization capability in Allstar within its self it is basically flat.
> In
> > the future there may be a way to do equalization in the IOpipe channel
> > driver. If you have a circuit, transceiver etc. that has poor audio
> > characteristics it is best to try and fix that rather than trying to
> > correct it with SW. The other issue is every radio would have different
> > characteristics and if you have a node that has multiple users you would
> > just be chasing your tail trying to get things right for each user or
> radio.
> >
> >
> > *73 Doug*
> >
> > *WA3DSP*
> >
> > *http://www.crompton.com/hamradio <http://www.crompton.com/hamradio
> > _______________________________________________
> >
> > arm-allstar mailing list
> > arm-allstar at hamvoip.org
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> >
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> >
>
>