Hi I want to switch between tx and rx in a flow graph with my HackRF. I found this video that shows how it could be done. The key component is the Selector block which is now deprecated.

Is there a alternative way to the selector block method?

I also found this feature request. But the last comment is nearly 2 years old.


1 Answer 1


You can use a QT GUI Chooser as an alternative to the Selector Block when you want a tx/rx switch. The two multiply blocks (not counting the volume control) gate the transmit and receive signals.
This image is also available at https://wiki.gnuradio.org/index.php/File:Selector_demo.png

Transmit/Receive switch

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    $\begingroup$ I think thats not a solution to my question? What the Selector Block does is "Reroute" the flow graph based on a given Variable Value. What that does in the example given in the Video is: It basically switches between the actual Signal and a null Sink/Source. I think what you want me to do is to use an actual Radio and drive PTT through a GPIO? $\endgroup$
    – maxbit89
    Sep 27, 2019 at 7:09
  • $\begingroup$ @maxbit89 I think this will do what you want. $\endgroup$ Oct 20, 2019 at 20:15
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    $\begingroup$ I just found out that there is a replacement selector block github.com/gnuradio/gnuradio/pull/2483. It has been incorporated into 3.7 and 3.8 $\endgroup$ Oct 21, 2019 at 0:27

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