# Ok, I'm lost

**URL:** <https://www.ruby-forum.com/t/ok-im-lost/239916>\
**Category:** GNU Radio\
**Created:** [March 19, 2014, 7:01pm UTC](https://www.ruby-forum.com/t/ok-im-lost/239916 "2014-03-19T19:01:06Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\
**Post date:** [March 19, 2014, 7:01pm UTC](https://www.ruby-forum.com/t/ok-im-lost/239916/1 "2014-03-19T19:01:06Z")

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I’m trying to use gnuradio with wsjt. To do that, I need to make the gr  
audio source and sink look like a soundcard to the wsjt program. One  
might think this is simple; it is not or at least apparently not. I’ve  
been lost in the dismal swamp of the Linux sound “system” for about a  
week or so. What a mess. Lots of unclear info, looked at ALSA, Pulse  
(default on my 12.04 maachines) and Jack. Nothing is clear. It is  
clear that ALSA lies under all, that Jack won’t play with Pulse, that  
pulse can be suspended before running the Jack server, and that there  
are very few people out there that REALLY understand the audio setup in  
Ubuntu.  
Anyone have a cooment? Is the easiest way really to put on another sound  
card and hook two of them back-to-back?  
Thanks, I’ll keep swinging, even though the machine is throwing all  
sinkers 🙂  
Don

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**Author:** ![djl](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/a183cd/32.png) [@djl](https://www.ruby-forum.com/u/djl)\
**Post date:** [March 19, 2014, 7:23pm UTC](https://www.ruby-forum.com/t/ok-im-lost/239916/2 "2014-03-19T19:23:54Z")

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On Wed, Mar 19, 2014 at 6:59 PM, djl [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> card and hook two of them back-to-back?  
> Thanks, I’ll keep swinging, even though the machine is throwing all sinkers  
> 🙂

Hi Don,

The audio system on Ubuntu is really simple: ALSA provides the low  
level access to the hardware and on top of that you have pulseaudio  
which is what applications are supposed to use. However, applications  
can also use ALSA directly bypassing pulseaudio and this is what GNU  
Radio does by default.

I do not know the wsjt application and what it uses for audio backend.  
If it uses pulseaudio, you can try to use the “pulse” ALSA device in  
gnuradio and route to/from wsjt using the pulseaudio volume control  
application: pavucontrol.

If wsjt uses ALSA you can try to create an ALSA loopback device, which  
sounds more like what you ask for. See for example these pages:

> **[Matrix:Module-aloop - AlsaProject](https://www.alsa-project.org/main/index.php/Matrix:Module-aloop)**

[http://ubuntuforums.org/archive/index.php/t-914405.html](http://ubuntuforums.org/archive/index.php/t-914405.html)

Note that your problem is not really a gnuradio specific issue and you  
may get better answers on a linux or ubuntu forum.

Alex