QT GUI Push Button, QT GUI Toggle Switch, QT GUI LED Indicator, Logical

Hello,

there is a problem with the initialisation of

<QT GUI Toggle Switch>.

In the meantime, I find out self what happens.

The problem is the <QT GUI Toggle Switch>.

The <QT GUI Toggle Switch> is NOT properly initialised

on startup, so it gives an error message

if you reference it in another block for example in

a Boolean expression like x = a | b.

The initialisation of <QT GUI Toggle Switch>

is only done if you activate it the first time.

The you can reference it without problems.

The workaround is, an intermediate variable

between the button and the LED.

See flowgraph.

I think, this must be fix in the future...

(The same problem is also on <QT GUI Check Box>)

 

FOSDEM 2026 (Feb. 1 2026): call for contributions on SDR/DSP (deadline Nov. 15 2025)

The Software Defined Radio/Digital Signal Processing (SDR/DSP) devroom
is being organized for the 2026 FOSDEM held in Brussels (Belgium)
Sunday Feb. 1, 2026.

We are seeking contributions discussing FOSS software for
(radiofrequency) discrete time digital signal processing/software
defined radio (SDR) including digital communication and data integrity
(CRC calculation, Forward Error Correction -- FEC), communication
channel characterization, navigation and positioning, target ranging and
velocity measurement, and signal characteristics extraction from raw IQ
collected from single or multiple antennas, as well as software
frameworks easing such applications including GNU Radio, FutureSDR,
Pothosware or custom frameworks. Novel openhardware description,
possibly including the latest acceleration peripherals including FPGA
and GPUs (or others), is encouraged, especially if using FOSS
frameworks, but maybe also demonstrating how a radiofrequency grade
oscilloscope can make an excellent (discontinuous stream) SDR receiver.

Proposals should be submitted through https://pretalx.fosdem.org by
November 15 at latest, or 2 weeks from now.

See you in Brussels, Jean-Michel

QT GUI Push Button, QT GUI Toggle Switch, QT GUI LED Indicator, Logical problem

Hello,

 

I'm using GnuRadio 3.11 on Ubunu 2025.10

and I run into a logical problem with

 

QT GUI Push Button

QT GUI Toggle Switch

QT GUI LED Indicator

 

I have configured in the LED Indicator block

  state = button | switch

 

With this configuration, the using behaviour

after startup is different for

  a) first button then switch (works fine)

but the sequence

  b) first switch then button (give me an error message)

 

I have isolate this in the flowgraph ButtonAndSwitchTest.grc

I need this to activate something steady or temporarly...

 

Is this a mistake from me?

It seems to be, a problem in the initialisation.

And is there a workaround for that?

 

Thanks

Re: Using GNU Radio with SDRplay RSPduo

On Sun, 26 Oct 2025 21:14:03 -0400 (EDT)
Franco VENTURI <fventuri@comcast.net> wrote:
> Chris,
> my idea was/is to create a native GNU Radio module for the SDRplay RSPs, similar to what gr-uhd is for the USRPs.
[snip]

Franco,

That's most informative, I'll give gr-sdrplay3 a try.

Thanks for all you do to maintain this support by the way.

Chris

Re: Using GNU Radio with SDRplay RSPduo

Chris,
my idea was/is to create a native GNU Radio module for the SDRplay RSPs, similar to what gr-uhd is for the USRPs.

The SoapySDR framework is good for many use cases, for instance when you want to be able to use the very same flowgraphs for different types of SDR hardware from different manufacturers.
Unfortunately being a generic SDR interface it is not really able to capture the unique aspects of each SDR hardware. For instance the handling of gains and gain reductions in the SoapySDRPlay3 module tries to bridge the way the SDRplay API defines them with the way the SoaySDR specification expects them, and the overall user/developer experience is not that great.

I also suspect that being able to output the I/Q samples directly in the GNU Radio 'work()' function should make streaming more efficient and less CPU intensive for the native gr-sdrplay3 OOT module, since only one set of intermediate buffers is used. I have never run full tests to validate if this is true, and if someone has done a comparison between the two approaches, I would be interested in hearing from them.

As I was typing this message, another case where the gr-sdrplay3 OOT module might be preferable is when the GNU Radio Companion flowgraph needs to be able to set say the tuning frequency via a message port, or perhaps needs to know exactly at which sample the gain changed because of the AGC. I don't think it is possible to achieve something like this with the SoapySDR driver and gr-soapy, while gr-sdrplay3 supports both message ports and stream tags natively.

Franco


> On 10/26/2025 2:32 PM EDT Chris Vine <vine24683579@gmail.com> wrote:
>
>
> On Sun, 26 Oct 2025 12:14:53 -0400 (EDT)
> Franco VENTURI <fventuri@comcast.net> wrote:
> > If you are planning to use the 'gr-sdrplay3' OOT module you can find
> > some simple GNU Radio Companion flowgraphs here:
> > https://github.com/fventuri/gr-sdrplay3/tree/main/examples
> >
> > Franco
>
> I've not tried gr-sdrplay. What is its advantage over using gr-soapy
> with the SoapySDRPlay3 plugin (which I think you also maintain)?
>
> Chris

Re: Using GNU Radio with SDRplay RSPduo

On Sun, 26 Oct 2025 12:14:53 -0400 (EDT)
Franco VENTURI <fventuri@comcast.net> wrote:
> If you are planning to use the 'gr-sdrplay3' OOT module you can find
> some simple GNU Radio Companion flowgraphs here:
> https://github.com/fventuri/gr-sdrplay3/tree/main/examples
>
> Franco

I've not tried gr-sdrplay. What is its advantage over using gr-soapy
with the SoapySDRPlay3 plugin (which I think you also maintain)?

Chris

Re: Using GNU Radio with SDRplay RSPduo

If you are planning to use the 'gr-sdrplay3' OOT module you can find some simple GNU Radio Companion flowgraphs here: https://github.com/fventuri/gr-sdrplay3/tree/main/examples

Franco


> On 10/26/2025 8:39 AM EDT Chris Vine <vine24683579@gmail.com> wrote:
>
>
> On Sat, 25 Oct 2025 22:21:19 +0000
> Andrew Thornett <andrew@thornett.net> wrote:
> > Hi All,
> >
> > Has anyone got an effective GRC for using GNU Radio with SDRplay devices?
> >
> > Andy
>
> I have a GRC file for a 100kHz to 200MHz AM/USB/LSB/DSB/NBFM receiver
> using gr-soapy's SDRPlay implementation which I use with a RSP1A.
> Whether it is "effective" for your purposes I have no idea.
>
> I don't use it a great deal - I mostly did it for pedagogical purposes.
> I use it from time to time but generally prefer gqrx or CubicSDR with
> the RSP1A.
>
> Chris