Re: [Discuss-gnuradio] Is that possible combining usrp_fft.py and usrp_spectrum_sense.py to do spectrum analysis and observe in GUI in a wider frequency range?

[Eric Blossom]

On Wed, Dec 05, 2007 at 03:54:50PM -0800, Brook Lin wrote:
> 
> Hi All,
> 
> I am new to Gnuradio. I did some test and simple implementation. Now, I have
> a question about combining usrp_fft.py and usrp_spectrum_sense.py. 
> 
> I know that usrp_fft.py gives a spectrum at certain center frequency I
> specified, and shows the result in a GUI window. By changing the decimation,
> I can get the spectrum at interested frequency within different bandwidth.
> Say, if decimation is 16, the bandwidth shown in GUI is 4M, if option -8 is
> applied and decimation is 4, a 16M bandwidth can be got. So that means that
> I can do the spectrum analysis and observe it in GUI window just within 16M.
> 
> Later on, I found that usrp_spectrum_sense.py can be used to analysis
> spectrum within any frequency range, I just need to specify the lower bound
> and upper bound of the frequencies. And I can save the output to a file and
> plot it using Matlab. However, I want to observe the spectrum in a GUI
> window, like usrp_fft does, rather than the output file. 
> 
> Is that possible that by modifying usrp_fft.py and combining it with
> usrp_spectrum_sense.py, the spectrum within a wider range of frequencies can
> be observed in a GUI window? 

Yes.  Note however that at this moment there is a known problem with
usrp_spectrum_sense.py (actually believed to be in gr_feval_dd) that
causes a segmentation fault.  See ticket:199
http://gnuradio.org/trac/ticket/199

Eric