Re: [Discuss-gnuradio] BER Example - With QT Gui Chooser for Different Modulations Issue

[Cinaed Simson]

Okay, I was really trying to get you do a BER calculation just once -
without getting distracted by QT.

If you look at the output of the random number generator, it's output
appears to be unsigned bytes.

But the output of Constellation decoder, appears to be signed bytes.

At the BER inputs, you're comparing unsigned bytes to signed bytes.

Also, you don't know if the byte streams at the BER terminals are in sync.

The actually BER of your flowgraph is on the order of 30%. A signed byte
maybe 14% of the error (1/7)?

It's impossible to compare the output of the random number generator to
the output of the constellation decoder - 4 bytes of the decoder creates
a float which has a magnitude of roughly 100 - which 100 times large
then the random number.

So I replaced replaced the random source with a GLFSR source and the
inputs to the BER line up nicely in the time sink. The BER is 0x10**-6.

And one last point the symbols for bpsk are 0,1 - not -1,1 - the latter
are the constellation points for bpsk.

Just needs some random noise source.

Note, I'm just making this up as I go along - I've never done a BER
calculation.

-- Cinaed


On 1/22/19 8:29 PM, Luis Felipe Albarracin Sanchez wrote:
> Hello Cinaed and all,
> 
> Thanks for the response.
> 
> Mainly I want to change the modulation directly while running the
> flowgraph (either by QT GUI Chooser or other switch), without having
> others in parallel for future control systems implementations.´
> 
> I don´t know if  you have any ideas or guidelines for this.
> 
> Once again thank you.
> 
> Kind Regards.
> 
> On Tue, Jan 22, 2019 at 9:22 PM Cinaed Simson <address@hidden
> <mailto:address@hidden>> wrote:
> 
>     On 1/22/19 1:54 PM, Luis Felipe Albarracin Sanchez wrote:
>     > Hello Cinaed, Discussion List,
>     >
>     > Once again thank you for the response,
>     >
>     > Please believe me that i have gone through tutorials, and i have
>     > understood that in the python Top block i could enable/disable
>     blocks, i
>     > also went through this specific one for modulations:
>     >
>     > https://wiki.gnuradio.org/index.php/Guided_Tutorial_PSK_Demodulation
>     >
>     > An you are totally correct regarding how to modulate properly, 
>     > nevertheless what i am trying to do is that while the flowgraph is
>     > running, to switch the modulation (even if is not totally tuned) and
>     > that i can see that modulation in the QT  GUI.
>     >
>     > That´s why, if you take a look at my flowgraph you see how I
>     create a QT
>     > Chooser so I can select the modulation.
>     >
>     > My main problem is that i can not get it to work, it does not
>     switch to
>     > other modulation when I switch in the QT Gui while I run the
>     flowgraph.>
>     > I would appreciate any ideas regarding this, and also i f you (Cianed)
>     > could describe me a little more how a Hierarchical Block could help me
>     > in this.
> 
>     For hierarchical Block - see the tutorials and Google.
> 
>     I use QT for passing variables and parameters - but I mainly use the
>     command line. So I can't help you with QT.
> 
>     See if you can actually calculate BER for a single psk - say BPSK -
>     configure by a Constellation Object.
> 
>     If that works, then add another Constellation Object - say for QPSK -
>     configured - only for QPSK - so now you have 2 Constellation Objects in
>     the flowgraph.
> 
>     Now run them in parallel using BER Curve.
> 
>     -- Cinaed
> 
> 
> 
>     >
>     > Once again thank you all.
>     >
>     > Kind regards.
>     >
>     > On Tue, Jan 22, 2019 at 3:51 PM Cinaed Simson
>     <address@hidden <mailto:address@hidden>
>     > <mailto:address@hidden <mailto:address@hidden>>>
>     wrote:
>     >
>     >     On 1/22/19 8:51 AM, Luis Felipe Albarracin Sanchez wrote:
>     >     > Hello Cinaed,
>     >     >
>     >     > Thank you for the quick response,
>     >     >
>     >     > I look at your flowgraph, and i appreciate al the
>     corrections you
>     >     told me.
>     >     >
>     >     > I must just say that i was guiding myself through the examples
>     >     that are
>     >     > under the folder digital when you install GNU Radio.
>     >
>     >     Those examples presume you have already gone through the
>     tutorials.
>     >
>     >     >
>     >     > I took your model, and did some changes to mine (attached my
>     new file)
>     >     > but i still can´t get in the QT GUI to switch between different
>     >     > modulations, if i start with 8-QAM  it does not switch to
>     QPSK when i
>     >     > choose QPSK in the  QT Chooser, i would appreciate if you
>     can give me
>     >     > any ideas regarding this.
>     >
>     >     Right click on the Constellation Object, and there's a pull
>     down menu
>     >     under Constellation Type  - select the one you want.
>     >
>     >     If that's not what you're looking for then you have to figure
>     out how to
>     >     do whatever it is you want to do. And it may require creating a
>     >     hierarchical block.
>     >
>     >     My advice is to work through the tutorials.
>     >
>     >     -- Cinaed
>     >
>     >
>     >     >
>     >     > Kind regards.
>     >     >
>     >     >
>     >     >
>     >     > On Tue, Jan 22, 2019 at 1:00 AM Cinaed Simson
>     >     <address@hidden <mailto:address@hidden>
>     <mailto:address@hidden <mailto:address@hidden>>
>     >     > <mailto:address@hidden
>     <mailto:address@hidden> <mailto:address@hidden
>     <mailto:address@hidden>>>>
>     >     wrote:
>     >     >
>     >     >     On 1/21/19 3:47 PM, Luis Felipe Albarracin Sanchez wrote:
>     >     >     > Hello all,
>     >     >     >
>     >     >     > I am exploring  the BER measurements in GNU Radio for
>     different
>     >     >     > modulations (I know Error Rate is deprecated) but i tried
>     >     the example
>     >     >     > under the digital folder for BER measurement and I
>     >     understood all the
>     >     >     > flowgraph.
>     >     >     >
>     >     >     > After this i wanted to change the modulation in the QT
>     GUI so i
>     >     >     added a
>     >     >     > QT Gui Chooser as seen in the flowgraph below:
>     >     >     >
>     >     >     > Captura de pantalla de 2019-01-21 18-37-34.png
>     >     >     >
>     >     >     >
>     >     >     > Attached is the flowgraph for reference.
>     >     >     >
>     >     >     > When i add this i expected that the Constellation
>     would change
>     >     >     > accordingly, but it does not  when i choose a different
>     >     constellation
>     >     >     > with the chooser, for instance if the default value in the
>     >     chooser is
>     >     >     > QPSK it shows at the beginning:
>     >     >     >
>     >     >     > Captura de pantalla de 2019-01-21 18-44-25.png
>     >     >     >
>     >     >     > But  If i switch in the same running time to 8-PSKn it
>     shows:
>     >     >
>     >     >     Everything - I mean everything - was configured with 8PSK
>     >     constellation
>     >     >     data- and incorrectly - even the random number generator!
>     >     >
>     >     >     I'm surprise you could see anything!
>     >     >
>     >     >     Enclosed is the proper way to create a QPSK constellation.
>     >     >
>     >     >     Work through the tutorials at
>     >     >
>     >     >       https://wiki.gnuradio.org/index.php/Tutorials
>     >     >
>     >     >
>     >     >     -- Cinaed
>     >     >
>     >     >
>     >     >     >
>     >     >     > Captura de pantalla de 2019-01-21 18-44-44.png
>     >     >     >
>     >     >     >
>     >     >     > Which is not an 8-PSK modulation scheme.
>     >     >     >
>     >     >     > I would appreciate some help,. regarding what i am doing
>     >     wrong  for
>     >     >     > choosing a Modulation through the QT GUI.
>     >     >     >
>     >     >     > Thanks in advance.
>     >     >     >
>     >     >     > Kind Regards.
>     >     >     >
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>     >     >
>     >     > --
>     >     > Eng. Luis Felipe Albarracin
>     >     > Msc. Telematics / MBA
>     >     > PMP
>     >     > CCNA/CCDA/CCNP/CCDP/CCIP
>     >     > ITIL v3 Foundation
>     >     > "Die Grenzen meiner Sprache bedeuten die Grenzen meiner Welt"
>     >
>     >
>     >
>     > --
>     > Eng. Luis Felipe Albarracin
>     > Msc. Telematics / MBA
>     > PMP
>     > CCNA/CCDA/CCNP/CCDP/CCIP
>     > ITIL v3 Foundation
>     > "Die Grenzen meiner Sprache bedeuten die Grenzen meiner Welt"
> 
> 
> 
> -- 
> Eng. Luis Felipe Albarracin
> Msc. Telematics / MBA
> PMP
> CCNA/CCDA/CCNP/CCDP/CCIP
> ITIL v3 Foundation
> "Die Grenzen meiner Sprache bedeuten die Grenzen meiner Welt"

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