# Best way to output decoded data to user

**URL:** <https://www.ruby-forum.com/t/best-way-to-output-decoded-data-to-user/240454>\
**Category:** GNU Radio\
**Created:** [April 15, 2014, 6:15am UTC](https://www.ruby-forum.com/t/best-way-to-output-decoded-data-to-user/240454 "2014-04-15T06:15:56Z")\
**Posts on this page:** 14\
**Page:** 1

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**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\
**Post date:** [April 15, 2014, 6:15am UTC](https://www.ruby-forum.com/t/best-way-to-output-decoded-data-to-user/240454/1 "2014-04-15T06:15:56Z")

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Hi,

I’m trying to figure out the best way to print the decoded data  
information  
of packets (received through gnuradio) to the user. File outputs are not  
really user friendly so I’m thinking of using a message queue out of my  
decoding block connected to the WX GUI Terminal Sink.

Is this a good approach? I’m thinking it might not since I can’t find  
any  
design using the terminal sink on the net.

If this is the right path could someone point me to an easy example of  
using the message queue. I’d like to do a quick proof of concept and  
output  
something like “hello world” on the terminal sink.

Thanks

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**Author:** ![Francois\_Gervais](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/e19adc/32.png) [@Francois\_Gervais](https://www.ruby-forum.com/u/Francois_Gervais)\
**Post date:** [April 15, 2014, 10:37am UTC](https://www.ruby-forum.com/t/best-way-to-output-decoded-data-to-user/240454/2 "2014-04-15T10:37:14Z")

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On 04/15/2014 06:14 AM, Francois Gervais wrote:

> I’m trying to figure out the best way to print the decoded data  
> information of packets (received through gnuradio) to the user. File  
> outputs are not really user friendly so I’m thinking of using a message  
> queue out of my decoding block connected to the WX GUI Terminal Sink.

Generally: Don’t use a message queue. Also, I recommend not adding any  
WX widgets, unless you hate QT, because we’re trying to move away from  
them.

The message passing interface might be a better choice, but the idea in  
general is very good.

> Is this a good approach? I’m thinking it might not since I can’t find  
> any design using the terminal sink on the net.
> 
> If this is the right path could someone point me to an easy example of  
> using the message queue. I’d like to do a quick proof of concept and  
> output something like “hello world” on the terminal sink.

Have a look at the message\_debug code. It does most of what you want,  
but not in a widget, just on the console.

Martin

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<div class="post-metadata">

**Author:** ![Francois\_Gervais](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/e19adc/32.png) [@Francois\_Gervais](https://www.ruby-forum.com/u/Francois_Gervais)\
**Post date:** [April 15, 2014, 11:55am UTC](https://www.ruby-forum.com/t/best-way-to-output-decoded-data-to-user/240454/3 "2014-04-15T11:55:42Z")

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hi ,Martin B.  
well ,in my impression, the unit of is noisy is dB,so i feel fuzzy about  
the volt,  
thanks for your reply!

------------------ Original ------------------  
From: “Martin B.”;[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid);  
Date: Tue, Apr 15, 2014 04:35 PM  
To: "discuss-gnuradio"[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid);

Subject: Re: [Discuss-gnuradio] Best way to output decoded data to user

On 04/15/2014 06:14 AM, Francois Gervais wrote:

> I’m trying to figure out the best way to print the decoded data  
> information of packets (received through gnuradio) to the user. File  
> outputs are not really user friendly so I’m thinking of using a message  
> queue out of my decoding block connected to the WX GUI Terminal Sink.

Generally: Don’t use a message queue. Also, I recommend not adding any  
WX widgets, unless you hate QT, because we’re trying to move away from  
them.

The message passing interface might be a better choice, but the idea in  
general is very good.

> Is this a good approach? I’m thinking it might not since I can’t find  
> any design using the terminal sink on the net.
> 
> If this is the right path could someone point me to an easy example of  
> using the message queue. I’d like to do a quick proof of concept and  
> output something like “hello world” on the terminal sink.

Have a look at the message\_debug code. It does most of what you want,  
but not in a widget, just on the console.

Martin

---

<div class="post-metadata">

**Author:** ![Francois\_Gervais](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/e19adc/32.png) [@Francois\_Gervais](https://www.ruby-forum.com/u/Francois_Gervais)\
**Post date:** [April 15, 2014, 3:57pm UTC](https://www.ruby-forum.com/t/best-way-to-output-decoded-data-to-user/240454/4 "2014-04-15T15:57:02Z")

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Ah so message queue and message passing interface are two different  
things  
in gnuradio? Might be why I was confused. So what I want to look at is  
this  
page right?  
[http://gnuradio.org/doc/doxygen/page\_msg\_passing.html](http://gnuradio.org/doc/doxygen/page_msg_passing.html)

Got it I’ll for the WX widgets, I’ll stop using them. Is there an  
official  
QT terminal block?

I’ll take a look at pyqt but I’d prefer using official blocks if  
possible.

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<div class="post-metadata">

**Author:** ![Francois\_Gervais](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/e19adc/32.png) [@Francois\_Gervais](https://www.ruby-forum.com/u/Francois_Gervais)\
**Post date:** [April 15, 2014, 3:22pm UTC](https://www.ruby-forum.com/t/best-way-to-output-decoded-data-to-user/240454/5 "2014-04-15T15:22:13Z")

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check out gr-pyqt - this might be roughly what you are looking for  
I’ve added some very simple python blocks which can send and receiver  
pdus with strings stored in pmt u8vectors and can be easily dropped into  
a Qt Gui for user interaction

> <https://github.com/osh/gr-pyqt/commit/7b12b79bc029d483ce71878960b24871ddbfd954>

-Tim

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<div class="post-metadata">

**Author:** ![Francois\_Gervais](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/e19adc/32.png) [@Francois\_Gervais](https://www.ruby-forum.com/u/Francois_Gervais)\
**Post date:** [April 15, 2014, 6:15pm UTC](https://www.ruby-forum.com/t/best-way-to-output-decoded-data-to-user/240454/6 "2014-04-15T18:15:10Z")

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On Tue, Apr 15, 2014 at 12:03 PM, Martin B.  
[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)wrote:

> Not yet 🙂 If you want to get your hands dirty, that would be nice…
> 
> Martin

Someone actually uses the terminal block? That one in WX has always felt  
completely broken to me and I had no interest in duplicating it in QT.  
But  
hey, if it’s being used, it’s something we would like to have.

Tom

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**Author:** ![Francois\_Gervais](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/e19adc/32.png) [@Francois\_Gervais](https://www.ruby-forum.com/u/Francois_Gervais)\
**Post date:** [April 15, 2014, 6:19pm UTC](https://www.ruby-forum.com/t/best-way-to-output-decoded-data-to-user/240454/7 "2014-04-15T18:19:54Z")

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Well I’m thinking if I’m about to print text to user it’s better if it’s  
part of the GUI than having some of the information on the GUI and some  
on  
the underneath console. That way it looks more like a self contained app  
to  
me.

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<div class="post-metadata">

**Author:** ![Francois\_Gervais](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/e19adc/32.png) [@Francois\_Gervais](https://www.ruby-forum.com/u/Francois_Gervais)\
**Post date:** [April 15, 2014, 6:05pm UTC](https://www.ruby-forum.com/t/best-way-to-output-decoded-data-to-user/240454/8 "2014-04-15T18:05:08Z")

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On 04/15/2014 03:55 PM, Francois Gervais wrote:

> Ah so message queue and message passing interface are two different  
> things in gnuradio? Might be why I was confused. So what I want to look  
> at is this page right?  
> [http://gnuradio.org/doc/doxygen/page\_msg\_passing.html](http://gnuradio.org/doc/doxygen/page_msg_passing.html)

Right.

> Got it I’ll for the WX widgets, I’ll stop using them. Is there an  
> official QT terminal block?

Not yet 🙂 If you want to get your hands dirty, that would be nice…

Martin

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<div class="post-metadata">

**Author:** ![Francois\_Gervais](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/e19adc/32.png) [@Francois\_Gervais](https://www.ruby-forum.com/u/Francois_Gervais)\
**Post date:** [April 15, 2014, 6:23pm UTC](https://www.ruby-forum.com/t/best-way-to-output-decoded-data-to-user/240454/9 "2014-04-15T18:23:27Z")

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On 04/15/2014 06:18 PM, Francois Gervais wrote:

> Well I’m thinking if I’m about to print text to user it’s better if it’s  
> part of the GUI than having some of the information on the GUI and some  
> on the underneath console. That way it looks more like a self contained  
> app to me.

And you’re right. But maybe a ‘terminal’ sink isn’t what we want, but  
rather a graphical tag/message debug/dump block?

Martin

---

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**Author:** ![Francois\_Gervais](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/e19adc/32.png) [@Francois\_Gervais](https://www.ruby-forum.com/u/Francois_Gervais)\
**Post date:** [April 15, 2014, 6:51pm UTC](https://www.ruby-forum.com/t/best-way-to-output-decoded-data-to-user/240454/10 "2014-04-15T18:51:47Z")

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On Tue, Apr 15, 2014 at 12:21 PM, Martin B.  
[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)wrote:

> On 04/15/2014 06:18 PM, Francois Gervais wrote:
> 
> > Well I’m thinking if I’m about to print text to user it’s better if it’s  
> > part of the GUI than having some of the information on the GUI and some  
> > on the underneath console. That way it looks more like a self contained  
> > app to me.
> 
> And you’re right. But maybe a ‘terminal’ sink isn’t what we want, but  
> rather a graphical tag/message debug/dump block?
> 
> Martin

Yeah, that sounds better to me. Or just a multi-line text box as a gui  
widget. It shouldn’t be difficult for someone to take the QT Number Sink  
block and convert that to a multiline text output (and remote the  
QwtThermo  
widget). Have the number of lines be a constructor parameter and be able  
to  
resize it at runtime.

Tom

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**Author:** ![Francois\_Gervais](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/e19adc/32.png) [@Francois\_Gervais](https://www.ruby-forum.com/u/Francois_Gervais)\
**Post date:** [April 15, 2014, 7:41pm UTC](https://www.ruby-forum.com/t/best-way-to-output-decoded-data-to-user/240454/11 "2014-04-15T19:41:57Z")

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In this scenario would the message passing interface be the best input  
type?

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<div class="post-metadata">

**Author:** ![Francois\_Gervais](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/e19adc/32.png) [@Francois\_Gervais](https://www.ruby-forum.com/u/Francois_Gervais)\
**Post date:** [April 15, 2014, 11:38pm UTC](https://www.ruby-forum.com/t/best-way-to-output-decoded-data-to-user/240454/12 "2014-04-15T23:38:00Z")

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Martin B.-2 wrote

> Generally: Don’t use a message queue. Also, I recommend not adding any  
> WX widgets, unless you hate QT, because we’re trying to move away from  
> them.
> 
> The message passing interface might be a better choice, but the idea in  
> general is very good.
> 
> Martin

Is there a reason not to use the message queue; maybe it is being  
deprecated? I’m experimenting with it now to pass FFT vectors out of  
the  
flow into my python script to search for a frequency and tune  
demodulator,  
and I can poll the queue every 10ms with no issues. Should I be using  
another method? I don’t want to write a block just yet.

Thanks,  
Lou  
KD4HSO

–  
View this message in context:  
[http://gnuradio.4.n7.nabble.com/Best-way-to-output-decoded-data-to-user-tp47578p47611.html](http://gnuradio.4.n7.nabble.com/Best-way-to-output-decoded-data-to-user-tp47578p47611.html)  
Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com).

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**Author:** ![Francois\_Gervais](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/e19adc/32.png) [@Francois\_Gervais](https://www.ruby-forum.com/u/Francois_Gervais)\
**Post date:** [April 16, 2014, 7:22am UTC](https://www.ruby-forum.com/t/best-way-to-output-decoded-data-to-user/240454/13 "2014-04-16T07:22:10Z")

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On github

> **[GitHub - dl1ksv/gr-display: QT based PNG display sink for gnuradio](https://github.com/dl1ksv/gr-display)**
>
> QT based PNG display sink for gnuradio. Contribute to dl1ksv/gr-display development by creating an account on GitHub.

there is an qt based simple oot module gr-display that can be used to  
display character streams either in an text window or as png picture.  
I use this to display ax.25 packets images from weather satellites.

– Volker

Am 15.04.2014 23:36, schrieb madengr:

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**Author:** ![Francois\_Gervais](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/e19adc/32.png) [@Francois\_Gervais](https://www.ruby-forum.com/u/Francois_Gervais)\
**Post date:** [April 16, 2014, 1:57pm UTC](https://www.ruby-forum.com/t/best-way-to-output-decoded-data-to-user/240454/14 "2014-04-16T13:57:01Z")

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On 04/15/2014 07:41 PM, Francois Gervais wrote:

> In this scenario would the message passing interface be the best input type?

If I could choose, I would give an optional stream input, and search for  
tags (print those), as well as a message port.

Martin