[Discuss-gnuradio] Fwd: Log raw data from the usrp_spectrum

Marcus

This is an explicit answer and guide to the exact tutorials *I* needed to start capturing my particular dataset.

That said, a question on refinement (and I can put this on the list if you think there's sufficient interest):

Rather than capturing all the spectrum "all the time" I would like to create a GRC flowgraph (at least until I'm comfortable writing my own code) that will bin samples, look for a particular amplitude spike, and save the bin if the spike is detected. The specific application is to look at characteristic spectra of cloud-ground and cloud-cloud lighting impulses.

Do you have a suggestion?

Regards

Gerry

Hi Gerry,

I think it would be cool if you forwarded this to the list :) Generally,
it's never bad to ask one question too many, and if something
interesting comes out of a discussion, everyone will profit.

I think with "binning samples" you might need to channelize them into
different subbands?
You could do that with a set of band pass filters. This will surely be
functional, but will have a high computational load.
If your subbands are equally shaped, you could use the Polyphase
Channelizer to get a set of subbands, which will be much more efficient.

On each of these N subbands, you could use a squelch and only save the
passing signal into N file sinks.

Greetings,
Marcus

Thanks, Marcus. I'll be looking at Polyphase Channelizer as soon as I can get back to that system!

Regards

Gerry

On Mon, Dec 1, 2014 at 10:29 AM, Marcus Müller <address@hidden> wrote:

> When u say complex samples, i thought it should in time domain,

yes, these are time domain samples.

> I just want use USRP to
> collect the a wide band signal around and save the data to the txt file,

Usually, there's no good reason to save millions of samples in text
format -- it's not really useful, just big.
If you, for some reason, need that, you can either write your own sink
that does that, or use python, octave, matlab, C, C++, or whatever you
like to load the binaries and print out strings representing complex
numbers textually.

> so i use the usr_spectrum_sense.
usrp_spectrum_sense is really a visualization demo.
If you just want to save the signal from a USRP to a file, that's a two
block flow graph in the GNU Radio companion: Just connect the USRP
Source to a File Sink, parameterize both to your likings, and you're done.

If that sounds strange to you, I can really recommend going through the
guided tutorials 1, 2 and 3, and most of your questions will be answered :)
http://gnuradio.org/redmine/projects/gnuradio/wiki/Guided_Tutorials

Greetings,
Marcus

On 12/01/2014 05:14 PM, Leo Yang wrote:
> When u say complex samples, i thought it should in time domain, and after the
> the fft block, it transfer to frequency domain. I just want use USRP to
> collect the a wide band signal around and save the data to the txt file, so
> i use the usr_spectrum_sense.
>
> and how to make the binary samples visualized and could be processed?
> or the s2v is the thing I may consider?
>
>
>
> --
> View this message in context: http://gnuradio.4.n7.nabble.com/Log-raw-data-from-the-usrp-spectrum-sense-py-tp51503p51506.html
> Sent from the GnuRadio mailing list archive at Nabble.com.
>
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio

_______________________________________________
Discuss-gnuradio mailing list
address@hidden
https://lists.gnu.org/mailman/listinfo/discuss-gnuradio

Gerry Creager

NSSL/CIMMS

405.325.6371

++++++++++++++++++++++

“Big whorls have little whorls,

That feed on their velocity;

And little whorls have lesser whorls,

And so on to viscosity.”

Lewis Fry Richardson (1881-1953)