Working FM radio on GNU radio and POTHOS

Here is my paltry offering - a very simple FM radio with lots of sliders to fiddle about with:

Not the best sound quality, but it works :slight_smile:
Any suggestions for improvement welcomed.
.grc file: CLICKY LINKY
Download file and change from .xml to .grc


Hi TegwynTwmfatt,

Thanks for sharing.
I can not download the file, permission issue. Anybody succeeded with it?
It is interesting (to me) if equivalent can be made for Pothos.

@dpenev I’ll probably replicate it in pothos tomorrow .


Hover over the ‘CLICKY LINKY’ with your mouse and then do a right click with your mouse to save this file to the desktop and then open it in GNU Radio Companion as appropriate. Should save as FM_RADIO_08.grc

73 de Marty, KN0CK

Thanks Marty,

I actually think I should know how to download the file from the Internet after a few decades in front of the computer :slight_smile:
but I get 403: Forbidden. Bellow the wget log.

You have managed to get the file, correct?

–2017-04-04 09:23:30--
Resolving (…
Connecting to (||:80… connected.
HTTP request sent, awaiting response… 403 Forbidden
2017-04-04 09:23:30 ERROR 403: Forbidden.

sorry @dpenev - I think this website has blacklisted your IP address. Try this instead:

change .xml to .grc.

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Got it running here. I changed it to receive NOAA @ 162.400 NBFM and audio is fine.



@dpenev for Pothos, download this example:

Best way to do this is to select the ‘Raw’ tab and copy and paste to a .txt on your desk top. I’m using windows 10. Then rename the txt file to a .pothos file. The audio quality is much better than my GNU radio version.

Open the file in pothos and find the ‘Devce Args’ panel and type in: {“driver”:“lime”}. Press ‘Execute’.

The really good thing about Pothos is that it explains everything so is an excellent learning tool.

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I’m having trouble finding the ‘Device Args’ panel…

Found it. Working here.


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Hi @TegwynTwmfatt,

In the GRC I am not able to find the LimeSDR input selection.
Is it fixed to some particular input?
With a portable room antenna I kind of hear something on top of the noise.

Watched this one a while ago and found it useful. I watched it a few times and there were some tidbits that filled in some knowledge gaps for me.

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It seems to default to RX1_L, so plug the antennae into that socket. You could also try typing RX1_L into the Ch0: Antenna box.

I used this video to create the GNU radio sketch!

It seems it doesn’t work for me.

return _osmosdr_swig.source_sptr_set_antenna(self, antenna, chan)
RuntimeError: SoapyLMS7::setAntenna(RX, RX1_L) - unknown antenna name

But it is clear that RX1_L is used.

OK … just leave the box blank and it should default to RX1_L

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OK the Pothos FM example working also for me. It seems it also defaults to RX1_L and I had to set the Rx Front end Gain to 50.
I will try to spend some time on this framework next few days.

P.S. The digits (on the Pothos widgets) rendering seems to bother my eyes. Anyone having same issue or knowing how to improve? What I have on screen attached,

Seems to relate mostly with the case widgets are zoomed.

If memory serves, for antenna selection, use “LNAL”, “LNAH” or "LNAW " for source, and “BAND1” or “BAND2” for sink in “Ch0: Antenna”

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@Ismas I got Pothos to transmit using the SDR sink block with a ‘0’ in the channel box. It transmitted on TX1_1. No antenna info needed :relaxed:

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