# Re: pccc encoder **URL:** \ **Category:** GNU Radio\ **Created:** [April 12, 2015, 12:53am UTC](https://www.ruby-forum.com/t/re-pccc-encoder/241525 "2015-04-12T00:53:58Z")\ **Posts on this page:** 2\ **Page:** 1
**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 12, 2015, 12:53am UTC](https://www.ruby-forum.com/t/re-pccc-encoder/241525/1 "2015-04-12T00:53:58Z")
You are using the pccc decoder in an incorrect way. Please see attached corrected grc file: there are two ways to use the pccc decoder (i) either as a combo or (ii) in conjuction with trellis metrics. I have provided in your file both ways. Regarding you second question about whether you can define your own FSM: Of course you can! This is the whole idea of the FSM class! Please read the extensive documentation on how to do that in: /usr/local/share/doc/gnuradio-3.7.7git/html/gr-trellis.html (or wherever you have your documentation installed), and let us know if there is something you do not understand. Achilleas ---
**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 12, 2015, 4:34am UTC](https://www.ruby-forum.com/t/re-pccc-encoder/241525/2 "2015-04-12T04:34:00Z")
Hi. I understand the use of the trellis metrics block for the calculation of the costs, but I don`t understand the use of the constellation parameter, thats why I didn`t use that block before, I though it only was used in the cases were modulation was made. Thank you for correct my file. – View this message in context: [http://gnuradio.4.n7.nabble.com/pccc-encoder-tp53173p53271.html](http://gnuradio.4.n7.nabble.com/pccc-encoder-tp53173p53271.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com).