# New to Gnuradio, couple of questions

**URL:** <https://www.ruby-forum.com/t/new-to-gnuradio-couple-of-questions/232280>\
**Category:** GNU Radio\
**Created:** [September 29, 2014, 10:22pm UTC](https://www.ruby-forum.com/t/new-to-gnuradio-couple-of-questions/232280 "2014-09-29T22:22:24Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\
**Post date:** [September 29, 2014, 10:22pm UTC](https://www.ruby-forum.com/t/new-to-gnuradio-couple-of-questions/232280/1 "2014-09-29T22:22:24Z")

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I’m trying to become familiar with gnuradio, starting with grc, but I’ve  
run into a couple of stumbling blocks.

I’m using a USRP1 with an assortment of daughter boards, including LF-HF  
and VHF capabilities. I’d like to be able to sample the spectrum in  
relatively small segments, and capture the sample to a file, for  
particular  
amplitude exceedances. To be specific, I’m looking at lightning impulses  
and attempting to capture narrow segments of its discharge spectrum for  
analysis. Most of this will be below 100 khz, although I’m interested in  
systematically sampling from 10khz to 1 MHz. Of I can capture sufficient  
samples, I’ll perform wavelet and FFT analyses against them, to see if I  
can identify patterns.

Could someone spare a clue to a new guy, and point me either toward an  
appropriate starting point in Python, or a good place to start in a grc  
flowgraph?

Regards,  
Gerry

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**Author:** ![Gerry\_CreagerSNOA](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/f9ae1b/32.png) [@Gerry\_CreagerSNOA](https://www.ruby-forum.com/u/Gerry_CreagerSNOA)\
**Post date:** [September 29, 2014, 10:54pm UTC](https://www.ruby-forum.com/t/new-to-gnuradio-couple-of-questions/232280/2 "2014-09-29T22:54:50Z")

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Gerry,

It will probably take a bunch of experimentation to find something that  
works. Since you’re probably interested in the very beginning of the  
signal, you’ll need to do power detection in parallel with a delayed  
version of the signal so you trigger in time. Look up some of the  
following blocks:

- Delay
- RMS
- Burst Tagger
- Tagged File Sink

Since you’re capturing fairly short events, try recording bursts at full  
capture bandwidth (e.g., 1 MHz) to files, then do post processing as a  
second step. Find or make up some test signals to feed your flowgraph so  
you can work on it in good weather.

- Jeff

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**Author:** ![Gerry\_CreagerSNOA](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/f9ae1b/32.png) [@Gerry\_CreagerSNOA](https://www.ruby-forum.com/u/Gerry_CreagerSNOA)\
**Post date:** [September 29, 2014, 11:17pm UTC](https://www.ruby-forum.com/t/new-to-gnuradio-couple-of-questions/232280/3 "2014-09-29T23:17:30Z")

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Jeff

Thanks for the pointers. I’ll try these some time this week… hopefully  
before we see more lightning (Wed/Thurs). I do appreciate the help.

Regards  
Gerry

On Mon, Sep 29, 2014 at 3:53 PM, Jeff L. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> - Burst Tagger  
> On 09/29/2014 04:20 PM, Gerry Creager - NOAA Affiliate wrote:
> 
> > although I’m interested in systematically sampling from 10khz to 1 MHz.  
> > Gerry Creager
> 
> * * *
> 
> Discuss-gnuradio mailing list  
> [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
> [Discuss-gnuradio Info Page](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)