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

[Gerry Creager - NOAA Affiliate]

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 Long <address@hidden> wrote:

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
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Gerry Creager
N5JXS

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