[arm-allstar] Audio processing, was Re: cdm1250 transmit audio

Mon Mar 2 23:09:22 EST 2020

Chris,

  In all cases it is the radio(s)  - you are going through two radios at
both ends. If you ever talked from a radioless node to a radioless node you
would hear the difference, it is striking. But really 3K is plenty for good
communications especially when what you are hearing is cean and clear.

*73 Doug*

*WA3DSP*

*http://www.crompton.com/hamradio <http://www.crompton.com/hamradio>*

On Mon, Mar 2, 2020 at 10:39 PM "Chris Smart via ARM-allstar" <
arm-allstar at hamvoip.org> wrote:

> I have a much more basic audio question.
>
> what in an Allstar node chops things off around 3K? Is it the Baofeng
> radio module in most nodes, or is it something to do withthe fact that
> we're using pbx sofftware, so it treats everything as telephone audio?
>
>
>
> Sent from Chris's iPhone.
>
>
> > On Mar 2, 2020, at 16:51, Patrick Perdue via ARM-allstar <
> arm-allstar at hamvoip.org> wrote:
> >
> > I've gotten quite good results using hardware vocoders. DMR is far more
> robust than many give it credit for, especially if you don't use the
> software md380-emu implementation. Even some background is tolerated, which
> is pretty awesome when you consider the limited bandwidth and complexity of
> the DV modes. I'm always interested in improving audio wherever it can be
> improved, however.
> >
> >
> >> On 3/2/2020 3:12 PM, "Doug Crompton via ARM-allstar" wrote:
> >> Patrick,
> >>
> >>  First of all this is probably not happening soon. There are many other
> >> more important things on the list. Also it is almost impossible to
> improve
> >> something like crappy digital audio. If there was it would already be
> done.
> >> My suggestion is don't use it! But many people put up with it as they
> think
> >> it is some kind of advance in technology. Funny what you can seel
> people!
> >>
> >>
> >> *73 Doug*
> >>
> >> *WA3DSP*
> >>
> >> *http://www.crompton.com/hamradio <http://www.crompton.com/hamradio>*
> >>
> >> On Mon, Mar 2, 2020 at 3:01 PM "Patrick Perdue via ARM-allstar" <
> >> arm-allstar at hamvoip.org> wrote:
> >>
> >>> I'm definitely looking forward to any future audio processing support,
> >>> especially if SoX is involved, since we could then use ladspa. I would
> >>> especially like to process analog input to clean things up for digital
> >>> bridges. I'm thinking downward expander plus gate, so the digital
> >>> vocoders have less noise to process, especially with strong to moderate
> >>> analog signals, EQ and limiter. This could also help with the ever
> >>> present echo link 8-bit dithering. This is something I've wanted to do
> >>> for a while. Having a moderate downward expander and EQ or light
> >>> multi-band compression on my transmitted audio to Allstar would be nice
> >>> as well. Just something subtle to keep levels and equalization in line
> >>> between radios, but not to be obvious that there is processing.
> >>>
> >>>
> >>> On 3/1/2020 10:23 PM, "Doug Crompton via ARM-allstar" wrote:
> >>>> Jed,
> >>>>
> >>>>   Pre and de-emphasis are not meant to be used when they are applied
> to
> >>> the
> >>>> audio to/from the transceiver. Using them to make things sound more or
> >>> less
> >>>> bright when they have already been applied is not a good idea
> especially
> >>> on
> >>>> audio going out to the network. Pre-emphasis increases the high end
> at a
> >>>> prescribed rate for audio FROM your node, what you hear. De-emphasis
> >>>> decreases high end on audio TO your node, what others hear.  Most of
> us
> >>> are
> >>>> using radios that do this internally and leave these settings OFF. If
> you
> >>>> were using a radio that did not apply one or the other or both you
> would
> >>>> turn the appropriate one on. The bottom line is that they are not
> meant
> >>> for
> >>>> casual audio equalization but rather for a defined method every FM
> signal
> >>>> uses.
> >>>>
> >>>> It is in our plans and sometime in the future you will be able to
> apply
> >>>> software equalization using an external program such as sox but for
> ow if
> >>>> you must change equalization your best bet is feeding the analog audio
> >>> out
> >>>> of the FOB through a hardware equalizer.
> >>>>
> >>>>
> >>>> *73 Doug*
> >>>>
> >>>> *WA3DSP*
> >>>>
> >>>> *http://www.crompton.com/hamradio <http://www.crompton.com/hamradio>*
> >>>>
> >>>>
> >>>> On Sun, Mar 1, 2020 at 5:00 PM "Jed Barton via ARM-allstar" <
> >>>> arm-allstar at hamvoip.org> wrote:
> >>>>
> >>>>> Hey guys,
> >>>>>
> >>>>> So i'm trying to do some audio adjustment on my cdm1250 to make it
> >>>>> sound better.  I'm trying to figure out the pre-emphasis and
> >>>>> deemphasis on the radio.  I wanna add a little more high end to the
> >>>>> transmit audio.  Can i try this in simple USB, or where should i go?
> >>>>>
> >>>>> Cheers,
> >>>>>
> >>>>> Jed
> >>>>> _______________________________________________
> >>>>>
> >>>>> ARM-allstar mailing list
> >>>>> ARM-allstar at hamvoip.org
> >>>>> http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
> >>>>>
> >>>>> Visit the BBB and RPi2/3/4 web page - http://hamvoip.org
> >>>>>
> >>>> _______________________________________________
> >>>>
> >>>> ARM-allstar mailing list
> >>>> ARM-allstar at hamvoip.org
> >>>> http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
> >>>>
> >>>> Visit the BBB and RPi2/3/4 web page - http://hamvoip.org
> >>> _______________________________________________
> >>>
> >>> ARM-allstar mailing list
> >>> ARM-allstar at hamvoip.org
> >>> http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
> >>>
> >>> Visit the BBB and RPi2/3/4 web page - http://hamvoip.org
> >>>
> >> _______________________________________________
> >>
> >> ARM-allstar mailing list
> >> ARM-allstar at hamvoip.org
> >> http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
> >>
> >> Visit the BBB and RPi2/3/4 web page - http://hamvoip.org
> > _______________________________________________
> >
> > ARM-allstar mailing list
> > ARM-allstar at hamvoip.org
> > http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
> >
> > Visit the BBB and RPi2/3/4 web page - http://hamvoip.org
>
> _______________________________________________
>
> ARM-allstar mailing list
> ARM-allstar at hamvoip.org
> http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
>
> Visit the BBB and RPi2/3/4 web page - http://hamvoip.org