How to add fec in GMSK

Hello all,

I have previous posted a question concerning frame drops in GNU radio when using GMSK. (https://lists.gnu.org/archive/html/discuss-gnuradio/2020-04/msg00148.html)

On this mail someone answered that I should use OFMD (what I normally should consider because this is better), but my prof told me to focus on GMSK and also told me to include FEC. I know with one I should use, it is either the FEC en-/decoder or the Extended FEC en-/decode, because I shall stream data cte. 

So my question is how do you include this because I have tried but didn't succeed.

In the file attached you will find the grc with the FEC en-/decoder. Help would be appreciated.

Best regards,

Q