Signal in time domain

[Juan Doppler]

I'm beginning to use this sofware (gqrx 2.5.3 on ubuntu 14.04) and can't figure out a way to visualize (live) the received signal in the time domain.

I'm able to save it as wav to view it later but i would like to see the signal live. Is there a way to do this within the program? Or maybe using matlab/octave?

thank you!

[Alexandru Csete]

Hi Juan,

This feature is not implemented in gqrx so that's why you can't find it. Sorry.

Alex

[Juan Doppler]

Hi Alex

Ok, thanks.
I've trying to use the udp streaming but i can't figure out how to receive it on octave/matlab, has anyone been able to do this?

Juan

[jmly...@gmail.com]

Hi Juan:

You could probably build something in Perl to read the UDP stream and feed it to a plotting package, assuming you have documentation for the stream format.

Do some looking on the Comprehensive Perl Archive Network(www.cpan.org) for packages that might already do part of the process. I use a package called GD to draw a simulated o-scope screen with four curve traces. There's probably a package that can read a UDP stream.

James

[David Ranch]

Gqrx can save the demodulated audio via the "REC" button in the lower right AF window.  Obviously, that won't give you the option to see things in real time.  Another possibility might be to use ffserver to receive the UDP packets:

   http://ffmpeg.gusari.org/viewtopic.php?f=12&t=1268

and from there, send the output to STDOUT from where something like Baudline can show the timedomain:

   http://www.baudline.com/oscilloscope.html

--David
KI6ZHD

[Juan Doppler]

Thank you James and David.

I actually got it to work on octave using the udp streaming and a matlab toolbox.

Juan

[jmly...@gmail.com]

Juan:

Excellent! Please post the details for the next person who has an interest.

I have a small(20 line) Perl script working that reads, decodes, and prints the UDP data stream. I plan to feed this to my o-scope code when I get time to get back to it.

James

[jmly...@gmail.com]

I have a working wxPerl script to display the UDP raw audio stream. See attached output.

It's a little crude. It captures 600 packets and then produces the plot each time a button is pressed. More work to do to produce a continuous update.

Alex: It looks like I'm getting one sample per packet. Is this correct?

James

[Alexandru Csete]

On Wed, Mar 9, 2016 at 8:43 PM, <jmly...@gmail.com> wrote:
>
> Alex: It looks like I'm getting one sample per packet. Is this correct?

I have no idea since I'm just using the "off the shelf" UDP sink in
gnuradio, but it sounds very wrong.

Alex

[jmly...@gmail.com]

Alex:

That's what I thought also. I'll investigate further.

James