Re: [Discuss-gnuradio] (de)modulation problems gnuradio 3.7.3...also GRC FFT missing axis labels

[Tom Rondeau]

On Mon, Mar 17, 2014 at 11:49 PM,  <address@hidden> wrote:
> I successfully? installed gnuradio 3.7.3 from source on Ubuntu 12.04 using
> the gnuradio-build script, but am running into problems demodulating
> anything from a R820T based SDR.  GRC runs fine, but when I attempt to
> execute any blocks that include an AM, NFM, or WBFM demodulator I get a
> VOLK:Error allocating memory error.  I also noticed that if I just pipe the
> RTL-SDR source to a GUI FFT Sink (either QT or WX) there are no axis labels
> on the graphs....
>
> Attempting to receive WBFM using rtl_fm (per the examples on the rtl-sdr
> OsmoSDR website) produce only static.  It's not a signal strength issue per
> se as another radio can pick up  the station, and the SDR hardware is
> functional since I can receive WBFM with it normally via gqrx on a different
> machine.
>
> I'm wondering if there's a fundamental problem somewhere that's preventing
> demod from happening.  Any troubleshooting suggestions would be appreciated.
> Regards,
> R

Yes, these all sound like very low-level issues with your installation
or machine. You told us the OS you are using, but not the platform
(e.g., processor).

In the build directory of GNU Radio, you can run 'ctest' to see what
passes and what fails there. That might help clue us in. Also, you
should run volk_profile and make sure that completes without error
(that will take some time to complete).

Tom