Gqrx as complex UDP source in gnuradio

[DerekSP]

Hello. I am trying to use the output of gqrx as a source in my gnuradio flowchart, but I am having issues with displaying anything on the FFT sink. I followed an old post and changed the output type to short instead of complex, and that seemed to work, but I need complex output from gqrx to feed into a gmsk decoder that only accepts complex.

Any idea on how I can do that?

[Alexandru Csete]

The UDP output from gqrx is demodulated audio in 48 kHz, single
channel, S16LE format.
See http://gqrx.dk/doc/streaming-audio-over-udp

Alex

On Wed, Jul 10, 2019 at 10:50 PM DerekSP <derek...@gmail.com> wrote:
>
> Hello. I am trying to use the output of gqrx as a source in my gnuradio flowchart, but I am having issues with displaying anything on the FFT sink. I followed an old post and changed the output type to short instead of complex, and that seemed to work, but I need complex output from gqrx to feed into a gmsk decoder that only accepts complex.
> Any idea on how I can do that?
>

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[Alexander Fasching]

I have added optional dual channel streaming:
https://github.com/alexf91/gqrx/tree/stereo-udp

It can be selected in the audio settings window. I haven't really
tested it and there might be problems when packets are lost (maybe
inverted I/Q) or when the setting is changed.

[Javier Roldán]

Hi Alex,

Thanks for Gqrx. I love it.

The short seems very intuitive for me in all current cases... but when Receiver is in mode " Raw I/Q".
In such a case, what/how is exactly being sent in the UDP stream?

73,

Javier (EA1HEO)

On Thursday, 11 July 2019 12:32:46 UTC+2, Alexandru Csete wrote:

The UDP output from gqrx is demodulated audio in 48 kHz, single
channel, S16LE format.
See http://gqrx.dk/doc/streaming-audio-over-udp

Alex

On Wed, Jul 10, 2019 at 10:50 PM DerekSP <dere...@gmail.com> wrote:
>
> Hello. I am trying to use the output of gqrx as a source in my gnuradio flowchart, but I am having issues with displaying anything on the FFT sink. I followed an old post and changed the output type to short instead of complex, and that seemed to work, but I need complex output from gqrx to feed into a gmsk decoder that only accepts complex.
> Any idea on how I can do that?
>
> --
> You received this message because you are subscribed to the Google Groups "Gqrx SDR" group.

> To unsubscribe from this group and stop receiving emails from it, send an email to gq...@googlegroups.com.

[Alexander Fasching]

With the current version of Gqrx, you only get one channel over UDP,
regardless of the demodulator setting. The second channel is discarded.
For Raw I/Q demod, you will end up with the real component of the
signal in the demodulator window at 48 kHz sample rate.
The signal is multiplied by 32767 and sent as signed 16-bit integers.

I have a branch which supports stereo streaming:
https://github.com/alexf91/gqrx/tree/stereo-udp
You can switch between mono and stereo in the audio settings window in
the audio dock widget.
I think there are some problems where processing starts in the
background whenever the setting is changed, but this doesn't affect
streaming itself.

> send an email to gqrx+uns...@googlegroups.com.

> To view this discussion on the web visit

> https://groups.google.com/d/msgid/gqrx/efca6746-511c-409f-9706-1b80a0e89019%40googlegroups.com
> .