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

[David McGough]

Hi Irv,

If the audio coming from the FR6000 is truly equalized to be
"discriminator audio," then it should sound tinny and you'd want to set 
deemphasis=yes in simpleusb.

If you've not tried it, note that you can dynamically change all these 
settings in the simpleusb-tune-menu program (admin menu option #12)...As 
you change the setting, you'll immediately hear the change in the audio on 
AllStar.

73, David KB4FXC


On Fri, 1 Dec 2017, Irvin Fontanes wrote:

> 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
> > > _______________________________________________
> > >
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> > >
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> > >
> >
> >
>