Re: [Discuss-gnuradio] New to Gnuradio, couple of questions

[Jeff Long]

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

On 09/29/2014 04:20 PM, Gerry Creager - NOAA Affiliate wrote:
> 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
> --
> Gerry Creager
> N5JXS
>
>
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