Re: [Discuss-gnuradio] saturation with multi_fft.py

[Eric Blossom]

On Tue, Oct 09, 2007 at 05:11:52PM -0400, address@hidden wrote:
> Thanks-
> 
> I just downloaded, compiled and installed this latest revision.  When I 
> test multi_scope.py in the mutli-antenna examples directory with this 
> release I get the same issue.  Please note, I have the LF_RX 
> daughterboards, so I change the daughterboard ID from BASIC to LF in the 
> python code.  I also eliminate the second factor of 4 decimation in the 
> host (sw_decim = 4) by setting it to 1.  I then run with the following 
> command:
> 
> multi-antenna]$ ./multi_scope.py -f0 -d250 -g0
> 
> while acquiring a 10 kHz 0.3 V p-p signal.  The max value shown in the 
> waveform on the gui is just over 25,000, which is way too much compared to 
> the standard usrp_fft.py, which by the way is no longer in the examples 
> directory; I used one from a previous release.  If I increase the input 
> voltage level to 0.4 V p-p, I get a jagged waveform with sharp 
> discontinuities.
> 
> So, my problem remains.  Any ideas?

What's your test signal?  Is it your 100kHz wide signal?
Can you try it with -d 400 as described below?

Eric

> On Tue, 9 Oct 2007, Eric Blossom wrote:
> 
> >With the halfbands, it's flat to about 70% of the passband.
> >decim = 320 gives 200kS/s complex baseband, a bit more than you'll
> >need.
> >
> >
> >Without the halfbands, I'd use about 4x the bandwidth of interest,
> >then filter and decimate in the host for the final channel selection.
> >In your case, I'd use decim = 160 giving 400kS/s.

Eric