# Question on incorporate different constellation indexing in gr-digital constellation objects

**URL:** <https://www.ruby-forum.com/t/question-on-incorporate-different-constellation-indexing-in-gr-digital-constellation-objects/240860>\
**Category:** GNU Radio\
**Created:** [May 3, 2014, 8:45am UTC](https://www.ruby-forum.com/t/question-on-incorporate-different-constellation-indexing-in-gr-digital-constellation-objects/240860 "2014-05-03T08:45:53Z")\
**Posts on this page:** 2\
**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:** [May 3, 2014, 8:45am UTC](https://www.ruby-forum.com/t/question-on-incorporate-different-constellation-indexing-in-gr-digital-constellation-objects/240860/1 "2014-05-03T08:45:53Z")

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Dear all,

I have a question related to the constellation objects in gr-digital.  
After  
checking the constellation.cc, I found the constellation of 8PSK and  
QPSK  
class are all Grey coded. Now I want to use a 8PSK constellation with  
natural mapping.

I know I can just modify the constellation indexing of the Grey mapped  
8PSK  
class. But I don’t want to change the 8psk class that gnuradio provided  
or  
to make a natural mapped 8psk class by copying the 8psk class and just  
modifying the indexing. Is there any clean way to get the natural mapped  
8psk class I wanted?

Thanks!  
Best,  
Zhe

–  
View this message in context:  
[http://gnuradio.4.n7.nabble.com/Question-on-incorporate-different-constellation-indexing-in-gr-digital-constellation-objects-tp47934.html](http://gnuradio.4.n7.nabble.com/Question-on-incorporate-different-constellation-indexing-in-gr-digital-constellation-objects-tp47934.html)  
Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com).

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**Author:** ![Zhe\_F](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/d07c76/32.png) [@Zhe\_F](https://www.ruby-forum.com/u/Zhe_F)\
**Post date:** [May 11, 2014, 4:20pm UTC](https://www.ruby-forum.com/t/question-on-incorporate-different-constellation-indexing-in-gr-digital-constellation-objects/240860/2 "2014-05-11T16:20:45Z")

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On Sat, May 3, 2014 at 2:44 AM, Zhe F. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> modifying the indexing. Is there any clean way to get the natural mapped  
> 8psk class I wanted?
> 
> Thanks!  
> Best,  
> Zhe

Have a read of:

> **[GNU Radio Manual and C++ API Reference: Digital Modulation](https://www.gnuradio.org/doc/doxygen/page_digital.html)**

That will explain a bit more about the constellation objects. You are  
perfectly safe setting up your own Constellation Object with whatever  
constellation and symbol mapping you want.

Tom