Xastir Development Snapshot + Soundmodem/AX.25 HOWTO's

Xastir Development Snapshot + Soundmodem/AX.25 HOWTO's

[Curt, WE7U]

Project: XASTIR  (xastir)
Package: xastir-development
Date   : 2009-05-21 08:37

Project "XASTIR" ('xastir') has released the new version of package
'xastir-development'. You can download it from SourceForge.net by
following
this link:
<https://sourceforge.net/project/showfiles.php?group_id=45562&release_id=623890>
or browse Release Notes and ChangeLog by visiting this link:
<https://sourceforge.net/project/shownotes.php?release_id=623890>

Homepage:  <http://www.xastir.org>

We've recently added HOWTO Wiki pages for "Soundmodem" and for
"Linux AX.25" configuration.  Please try them out and provide
feedback so we can improve upon them:

   <http://www.xastir.org/wiki/index.php/HowTos>

-- 
Curt, WE7U.				archer at eskimo dot com
http://www.eskimo.com/~archer
   Lotto:  A tax on people who are bad at math. - unknown
Windows:  Microsoft's tax on computer illiterates. - WE7U.
The world DOES revolve around me:  I picked the coordinate system!"

Re: Xastir Development Snapshot + Soundmodem/AX.25 HOWTO's

[Alan Crosswell]

Somewhat OT: but has anyone successfully used a USB sound "card" with
soundmodem?
/a

Curt, WE7U wrote:
> 
> Project: XASTIR  (xastir)
> Package: xastir-development
> Date   : 2009-05-21 08:37
> 
> Project "XASTIR" ('xastir') has released the new version of package
> 'xastir-development'. You can download it from SourceForge.net by
> following
> this link:
> <https://sourceforge.net/project/showfiles.php?group_id=45562&release_id=623890>
> 
> or browse Release Notes and ChangeLog by visiting this link:
> <https://sourceforge.net/project/shownotes.php?release_id=623890>
> 
> Homepage:  <http://www.xastir.org>
> 
> We've recently added HOWTO Wiki pages for "Soundmodem" and for
> "Linux AX.25" configuration.  Please try them out and provide
> feedback so we can improve upon them:
> 
>   <http://www.xastir.org/wiki/index.php/HowTos>
> 

Re: Xastir Development Snapshot + Soundmodem/AX.25 HOWTO's

[Bent]

2009/5/21 Alan Crosswell <alan@columbia.edu>:
> Somewhat OT: but has anyone successfully used a USB sound "card" with
> soundmodem?

I have successfully used soundmodem in 1200 b/s AFSK mode with a
SignaLInk USB box.I haven't tried 9600 b/s.

Best 73 de Bent/OZ6BL

Re: Xastir Development Snapshot + Soundmodem/AX.25 HOWTO's

[Dave Platt]

> Somewhat OT: but has anyone successfully used a USB sound "card" with
> soundmodem?

I've been able to make a soundmodem 1200-baud connection using a
SignaLink USB (setting the soundmodem PTT to /dev/null, since
the SignaLink USB has its own vox-driven PTT circuit).

Some tricks:

-  If possible, use the direct ALSA "hw:" interface, and set
    the soundmodem's sample rate equal to one of the "native"
    rates supported by your USB sound card.  This ensures that
    no DSP- or CPU-based sample rate conversion needs to be
    done.

-  With some USB sound cards this may not be possible... there
    are those which have *different* sample rate sets for input
    and output, and might not even have a single rate in common
    which works in both directions.  In this case, specify the
    ALSA "plughw:" interface, so that ALSA's sample-rate conversion
    plugin does the necessary rate conversions... it seems to work
    quite well.

-  Do *not* use the OSS compatibility driver for ALSA (e.g.
    the /dev/dsp interface).  Although this driver does
    attempt to perform sample-rate conversion, it doesn't do
    so at all well... I've seen periodic dropouts in the
    incoming data (sequences of sample values of zero) whenever
    the buffer wraps around.  This really mucks up digital
    modes!

-  Make sure you've got the most recent version of the
    soundmodem code (it looks as if it's up to version
    0.13).  There were some important patches to ALSA
    support a few months ago, which eliminate a bunch of
    errors and freezes during TX/RX switching... versions
    0.10 and earlier did not work well with ALSA USB.