Re: How to scan the whole ISM band?

Yes, I think I only need to know the power strength and don’t need to
decode the signals for searching the spectrum holes. I read the
usrp_spectrum_sense.py. I wonder how I can draw a spectrogram through
this program. I think the line 145 shows the source is the USRP.
However, I have no idea where the destination is. I thought I can get
the data through GNU Radio and then use Matlab to draw the spectrogram
to show the spectrum holes. In line 193, the connection seems without
the destination. How do you guys use this code to draw the spectrogram?
145Â Â Â Â self.u =
usrp.source_c(fusb_block_size=options.fusb_block_size,
146Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â fusb_nblocks=options.fusb_nblocks) Â
193Â Â Â Â Â self.connect(self.u, s2v, fft, c2mag, stats)
Â
Thank you,
Roy

Goodman Roy wrote am 2008-07-15 00:26:

Hi all,

I would
like to know if it is possible to sense the whole
band,2.4-2.4835GHz, through the USRP? However, the ADC can only
support 64Msamples/sec. How can I scan the whole ISM band and draw the
spectrogram of the ISM band,2.4-2.4835GHz, through the USRP?

You can receive 32MHz at a time, but you are limited to 8MHz through the
USB bus. You cannot scan the whole 2.4Ghz ISM band at a time, but you
can step through it. If you want to detect unused frequencies you’d
probably just want to calculate the power over a reasonable time
interval to decide if some is using the band in question.

You may want take a look at
gnuradio-examples/python/usrp/usrp_spectrum_sense.py [1]

Patrick

[1]
http://gnuradio.org/trac/browser/gnuradio/branches/releases/3.1/gnuradio-examples/python/usrp/usrp_spectrum_sense.py

Goodman Roy wrote am 2008-07-15 18:42:

However, I have no idea where the destination is. I thought I can get
the data through GNU Radio and then use Matlab to draw the spectrogram
to show the spectrum holes. In line 193, the connection seems without
the destination.

     self.connect(self.u, s2v, fft, c2mag, stats)

Connect takes a variable count of paramters, forming a chain: self.u is
connected to s2v, s2v is connected to fft and so on.
stats is the final sink and if you look at main_loop, it’s read out
there.

You can use a file sink to dump data to disk or a fft sink to diplay it
(or both). Have a look at gr-utils/src/python/usrp_fft.py [1].

If you are unsure how to combine the both, you can find some introducing
documents at the wiki [2]. I’d really recommend the Python Tutorial [3]
if you are new to python.

Patrick

[1]
http://gnuradio.org/trac/browser/gnuradio/branches/releases/3.1/gr-utils/src/python/usrp_fft.py
[2] http://www.gnuradio.org/trac/
[3] http://docs.python.org/tut/

Engineers motto: cheap, good, fast: choose any two
Patrick S.
Student of Telematik, Techn. University Graz, Austria

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