# Re: pccc encoder

**URL:** <https://www.ruby-forum.com/t/re-pccc-encoder/241451>\
**Category:** GNU Radio\
**Created:** [April 7, 2015, 5:06pm UTC](https://www.ruby-forum.com/t/re-pccc-encoder/241451 "2015-04-07T17:06:28Z")\
**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:** [April 7, 2015, 5:06pm UTC](https://www.ruby-forum.com/t/re-pccc-encoder/241451/1 "2015-04-07T17:06:28Z")

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There are several issues with your code:

1. a PCCC encoder (as any digital communication encoder) cannot accept a  
“sine wave” as its input!  
it only accepts discrete information.  
In this case it should be numbers {0,1,2,…,X-1} where X is the input  
alphabet size of your fsm’s.

2. The output cardinality of the PCCC is the product of the output  
cardinalities of the two FSMs that you are using,  
so in your case is 2^3 x 2^3 = 64, which is not consistent with the size  
of  
the modulation you are using

3. The interleaver length is user-defined and there is no such thing as  
an  
appropriate length (the longer the better performance… )

I suggest you look and try to understand the EXAMPLE (aptly named  
pccc.grc)  
in the gr-trellis/examples/grc  
and let us know if you have any questions on this particular example.  
Then you can move on to change it according to your needs.

Achilleas

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**Author:** ![Achilleas\_A](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/74df32/32.png) [@Achilleas\_A](https://www.ruby-forum.com/u/Achilleas_A)\
**Post date:** [April 8, 2015, 3:43am UTC](https://www.ruby-forum.com/t/re-pccc-encoder/241451/2 "2015-04-08T03:43:38Z")

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HI  
Thank you very much for your response, you really helped me.

In my last post, i made a mistake. The fsm that i wanted to use is  
fsm=1,2,[13,11]. If i understood well, i should use a 16qam modulation.

But i`m using an error rate block, just like in the example pccc.grc (only that i`m not using any channel), and at the number sink i`m having a ber value, when i shouldn`t have any.  
I dont`n know where is my mistake.

If you could help me, i really appreciate.  
FUNCIONApccc\_random\_chunks\_pcccdeccombo.grc  
[http://gnuradio.4.n7.nabble.com/file/n53214/FUNCIONApccc\_random\_chunks\_pcccdeccombo.grc](http://gnuradio.4.n7.nabble.com/file/n53214/FUNCIONApccc_random_chunks_pcccdeccombo.grc)

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