On Tue, Jun 28, 2011 at 4:48 PM, Minhoo Kim
<address@hidden> wrote:
Hello, I'm new to this mailing list and gnuradio.
sorry if I fail follow certain etiquettes..
what I'm trying to do now is to have a transmitter that hops around under
1ms, which needs to have 1MHz bandwidth and hop around in 10MHz range total
(at least).
the problem I'm having is that I can't get the USRP motherboard to generate
that high of frequency.
I need the motherboard to generate at least up to 10MHz range because the
signal needs to be hopped around pretty fast..
and has to be passed on to 2.4GHz range using RFX2400.
This is the error message I get:
File "multiplytest.py", line 86, in <module>
test_signal = my_top_block()
File "multiplytest.py", line 46, in __init__
fmtx = blks2.nbfm_tx (self.sample_rate/10, self.sample_rate, tau=75e-6,
max_dev=1e5)
File "/usr/lib/python2.6/dist-packages/gnuradio/blks2impl/nbfm_tx.py",
line 69, in __init__
40) # stopband atten dB
File "/usr/lib/python2.6/dist-packages/gnuradio/optfir.py", line 44, in
low_pass
taps = gr.remez (n + nextra_taps, fo, ao, w, "bandpass")
File
"/usr/lib/python2.6/dist-packages/gnuradio/gr/gnuradio_swig_py_general.py",
line 352, in remez
return _gnuradio_swig_py_general.remez(*args, **kwargs)
RuntimeError: gr_remez: insufficient extremals -- cannot continue
i looked up gr_remez, and I haven't really found a solution to get USRP to
have 10MHz bandwidth.
I did find that the frequency has to do with self.sample_rate, and the
highest rate I got was 2 Mega, which in turn can generate up to 1MHz because
of the nyquist rate.
I know the interpolation rate has to be in multiples of 4 ( 4, 8, 12, ...)
and the USRP rate hast to be 128Mega to match the USB data flow rate (I
don't know if that's the right term).
I have my code attached.
Another way I'm looking at is to change the center frequency of the
daughterboard, but I haven't been able to figure out to make that happen
fast enough.
so the questions are,
How to get the sample rate up to the maximum (which should be 32MHz in
theory)?
How to retune the daughterboard while it's running?
Any help/suggestions would be great!
I am using USRP1 and RFX2400.
http://old.nabble.com/file/p31947513/multiplytest.py multiplytest.py
Thanks for reading this.
--
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