Re: [Discuss-gnuradio] test_usrp_standard_tx[rx].cc doubts...

[Angilberto Muniz Sb]

Ok, I see your point, Eric. I'll try to generate a C++
version of SIGGEN -- I had so many problems with
PYTHON and WxGUI and so on, that I decided not to
touch it anymore... :-)

Thank you for the tip.

Angilberto.



--- Eric Blossom <address@hidden> wrote:

> On Mon, Jul 18, 2005 at 06:10:44PM -0700, Angilberto
> Muniz Sb wrote:
> > Matt
> > 
> > While playing with "test_usrp_standard_tx[rx].cc"
> > setting
> > "-c" flag, I was expecting the folloing:
> >  
> >      x    x     x
> >     x    x     x
> >    x    x     x 
> >   x    x     x
> >  x    x     x         ......
> >  
> > But its not what I am getting. 
> >  
> > If I change the code that deal with the "counting
> > flag" as:
> >  
> >      if (counting_p){
> >        for (int i = 0; i < N; i++) {
> >     
> >     counter += delta;
> >     
> >     buf[i] = host_to_usrp_short (counter & xffff);
> >     
> >     if (i < N/2) delta = 1;
> >     else delta = -1;
> >        }
> >      }
> >  
> > I would expect:
> >  
> >      x       x
> >     x x     x x 
> >    x   x   x    x 
> >   x     x x      x
> >  x       x         x  ......
> >  
> > I dont get it either...
> 
> These are *very* low frequeny ramps.  They are most
> likely not getting
> through the transformer on the basic tx board.
> 
> > Am I correct in my assumptions?
> 
> More or less.
> 
> > When I watch the DAC on the scope or when I plot
> it
> > whith Matlab I see some breakups like its
> outputting
> > in bursts... Is this the correct/expected
> behavior?
> 
> Should be continuous, but it will be hard to see.
> 
> You'll be much better off using
> gnuradio-examples/python/usr/usrp_siggen.py
> 
> If you're getting underruns, use a bigger value for
> the interpolation
> factor.  Try using -i 128.  That will result in
> 1MS/sec (complex)
> across the USB.
> 
> > Lets suppose I want to generate 10khz sin/cos wave
> --
> > can "test_usrp_standard_tx.cc" handle it whith
> some
> > modifications?
> 
> 
> Note again that you won't be able to see a 10kHz
> sine wave at baseband
> due to the transformer.  You can use the
> --duc-freq=1M option to put
> it up at 1MHz.
> 
> address@hidden usrp]$ ./usrp_siggen.py --help
> usage: usrp_siggen.py [options]
> 
> options:
>   -h, --help            show this help message and
> exit
>   --sine                generate a complex sinusoid
> [default]
>   --const               generate a constant output
>   --gaussian            generate Gaussian random
> output
>   --uniform             generate Uniform random
> output
>   -iINTERP, --interp=INTERP
>                         set fgpa interpolation rate
> to INTERP
>   -fFREQ, --freq=FREQ   set waveform frequency to
> FREQ
>   -aAMPL, --amplitude=AMPL
>                         set waveform amplitude to
> AMPLITUDE
>   -oOFFSET, --offset=OFFSET
>                         set waveform offset to
> OFFSET
>   -cFREQ, --duc-freq=FREQ
>                         set Tx DUC frequency to FREQ
>   -nNCHANNELS, --nchannels=NCHANNELS
>                         set number of output
> channels to NCHANNELS
>   -mMUX, --mux=MUX      set output mux register
> 
> 
> Eric
> 


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