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enter image description here I tried GNU Radio and got very high hopes, but even basic things do not really work and I have no idea why:

  1. Sine Generator: I use the "Signal Source" block and connected it to an "Audio Sink" (Sound Card). But when I start it the tone is intermittent. I tried multiple sample rates, 44.1,48,96,... . I added a "Throttle" block to avoid the OAOAOAO,... problem, nothing works to produce a continuous sound.

Warning: This flow graph contains a throttle block and another rate limiting block, e.g. a hardware source or sink. This is usually undesired. Consider removing the throttle block.

INFO: Audio sink arch: windows

h: No such file or directory

gr::pagesize: no info; setting pagesize = 4096

h: Permission denied

  1. I tried to play a simple *.wav from windows, could not open and play the file. It said that it could not open some .png Images.

What is the Problem with GNU Radio? How can I get it to work?

Marcus Müller
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Seppel W.
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1 Answers1

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So, as the warning says, don't add a Throttle block. It's only making things worse.

The sound card has its own sampling clock, which limits the rate at which the Signal Source can produce samples, and by adding a Throttle, you add a second thing that tries to limit the rate. That way, you guarantee that at some point, things will go wrong, because either of them is slightly slower (as you might know, there's no two oscillators in the world that have exactly the same frequency, and that applies to the CPU clock used for Throttle and for the oscillator in your soundcard, too) than the other, and if the Audio hardware is faster than the Throttle, it will run out of samples. So, remove the Throttle, it's only doing harm.

There's a lot of reasons that audio output might be chunky, and most of them are only indirectly related to GNU Radio. Notice that the windows port is relatively fresh, so there's a certain probability that things might go wrong there.

My guess, based on your (slightly misrepresented) output of aOaOaO is that you accidentally set the Audio Sink's "OK to block" to "No". That is not the right thing to do. Set it to "Yes".

Generally, when reporting such problems, a screenshot of your flow graph does wonders :)

Marcus Müller
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  • Hello, because I had many errors printed to the console when starting GnuRadio-companion started version v3.7.10.1/v1.1.2 (64-Bit Any CPU ) I installed v3.7.9.2/v1.1.1, which starts without showing errors. My Setup is: -Windows 7, 64 Bit -Core i5 (I think Ivy Bridge) -16GB RAM -OnBoard Sound and USB-Soundcard(same issues) Best Regards, Seppel P.S. Yes it is "aOaOaOa" – Seppel W. Nov 02 '16 at 10:50
  • and, did removal of the Throttle and setting "OK to block" to "true" help? – Marcus Müller Nov 02 '16 at 11:35
  • No, did not help, it just presented the "aOaOaOa". – Seppel W. Nov 02 '16 at 13:12
  • Hm, I'm reading the [source code](https://github.com/gnuradio/gnuradio/tree/master/gr-audio/lib/windows) once again, maybe something gives me an idea what might be going wrong :( Anyway, Geoff fixed something within the last 20 days within the windows audio sink, so it's probably wiser to use the modern version and get rid of the other errors. – Marcus Müller Nov 02 '16 at 13:40
  • By the way, I hate to leave you hanging for so long. Do you have a spare USB key or DVD burner? http://gnuradio.org/redmine/projects/gnuradio/wiki/GNURadioLiveDVD has a bootable image that you can use; in my experience it works great out of the box. The eu2-dist.gnuradio.org mirror is my server, should be pretty fast for Germany and neighboring countries. – Marcus Müller Nov 02 '16 at 13:44
  • the aOaOaO should be fixed in the most current version, if I read the code versioning correctly. But I'm not 100% sure. I'll have to discuss with Geof & co. – Marcus Müller Nov 02 '16 at 13:46
  • I will try the DVD, but not in the next 4 days, maybe on Sunday. But I promise to give you Feedback as soon as possible. – Seppel W. Nov 02 '16 at 15:17