Re: [Discuss-gnuradio] USRP network based spectrum analyzer

[Marcus D. Leech]

On 28/09/2011 4:50 PM, Phelps Williams wrote:
> I have a usrp and computer in a remote location without much network 
> bandwidth available to the system and I'm using it as a spectrum 
> analyzer.  I'd like to run the fft on the remote system and then send 
> the results to a connected client for display.  This would allow me to 
> get greater fidelity than xwindows forwarding or the ascii dft example 
> while also using less bandwidth.  I would imagine the client side 
> would potentially reuse some of the existing wx or qt interfaces for 
> display and control.
>
> This seems like a pretty useful / simple use of this hardware.  Does 
> anybody know of any implementations floating around that does this? 
>  I'd prefer not to reinvent the wheel.
>
> -Phelps
Because I'm such an insanely nice guy, I quickly implemented something 
like what you'd need.  Attached.

It uses a UHD source, computes a (default 2048-point) 10*log10-scaled 
FFT, then outputs the resulting float-vector to a file-sink at a 5Hz rate.

Everything is pretty-much parameterized on the command line, including:

     frequency         (100M)
     gain                   (20)
     srate                 (1.0e6)
     fifoname          ("fft_output_fifo")
     devicecfg         ("addr=192.168.10.2")
     xmlport            (6060)

I've included the ability to change parameters on-the-fly using the 
XMLRPC server, which would allow you to, for example, change
  run-time parameters from some external interface, such as a WEB gui 
or similar.

If this were my problem, I'd start this thing in a script which creates 
the fifo file, starts some program that reads the FIFO (left as an
  exercise for the proverbial reader) in the background, then calls the 
Gnu Radio program.

uhd_fft_to_file.grc
Description: Text Data

uhd_fft_to_file.py
Description: Text document