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List: gnuradio-discuss
Subject: Re: [Discuss-gnuradio] test_usrp_standard_tx[rx].cc doubts...
From: Angilberto Muniz Sb <angilberto () yahoo ! com>
Date: 2005-07-19 16:13:20
Message-ID: 20050719161320.45427.qmail () web33404 ! mail ! mud ! yahoo ! com
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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 <eb@comsec.com> 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.
>
> [eb@bufo 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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