Re: [Discuss-gnuradio] WBFM decoding flowgraph: Audio terminates when tuning

[matthew venn]

I doubt you've missed something basic! I don't know what I'm doing!

I followed Brian's suggestions - but then also changed to 24khz audio out to see if that would help.

So a decimate by 2 and then 20, so 960khz / 40 = 24khz.

I should also mention that I have poor reliability with limesdr. It lasts for 5 minutes at most before needing a restart, and needs constant

firmware reflashing. So this could also be an issue.

Matt

On 6 March 2018 at 17:20, Adrian Musceac <address@hidden> wrote:

Hi Matt,

Perhaps I'm missing something very basic, but I fail to see how you
reached the numbers for the sample rates. They look wrong to me. 1
Msps -> decimation by 4 -> 960 Ksps?

Regarding performance, I'd say some optimization is required for
better performance. I was able to demodulate WFM with gnuradio on a
1.2 GHz ARM mobile phone with plenty of CPU to spare (50% or more).
I can give you a flowgraph if you want, but it's C++ code not GRC.

Regards,
Adrian

On 3/6/18, matthew venn <address@hidden> wrote:
> Hi Brian and Adrian, thanks for the help.
>
> we've finally gotten around to having another go with gnuradio.
> Brian, I tried your settings and we have the same situation. Things work
> fine until we adjust the tuning, then something happens. There is still
> some crackling from the speakers, but
> we can never get the sound back, even if we retune to exactly where we
> started.
>
> Attached is the new patch, and the errors that get printed when we tune.
> One thing that has changed is there is no aU errors anymore.
>
>
>

> Regarding hardware, it's the LimeSDR. My PC is 6 core 3ghz FX6100 with 8gb
> ram. It hits 50% on one core with gnuradio companion running. When tuning I
> don't notice a difference.
> Thanks!
> Matt
>
>
> On 16 February 2018 at 22:42, Adrian Musceac <address@hidden> wrote:
>
>> Hi,
>> Based on your graph, the filter seems to be running at the same sample
>> rate as the source, even though you have a decimator block ahead of it.
>> I suggest to correct that and then try again.
>>
>> Cheers,
>> Adrian
>>
>> On February 16, 2018 8:42:13 PM UTC, matthew venn <address@hidden>
>> wrote:
>>>
>>> Hi all,
>>> I've got a limesdr that I'm using to learn about SDR. I started with the
>>> AM tutorial from the website and have now moved on to something that I
>>> can
>>> pickup with an antenna.
>>>
>>> The flow works, until I tune it. Then I get aU on the log, and the audio
>>> changes (it still makes noise), but I can never get the audio back even
>>> if
>>> I retune to exactly where it was.
>>>
>>> I can use the waterfall to find a new frequency, then stop the flow,
>>> type
>>> that new number as the default tuning and then start and hear audio
>>> again.
>>> Until I tune...
>>>
>>> Any idea why it breaks the audio when I tune it?
>>>
>>> Thanks,
>>> Matt
>>>
>>
>
>
> --
> Matthew Venn

> web mattvenn.net twitter @matthewvenn <https://twitter.com/matthewvenn>
>

--

Matthew Venn
web mattvenn.net twitter @matthewvenn