Re: How to add fec in GMSK

Hello Quenten:

Just to elaborate a bit further:  If you did something that is suggested in the example files, and failed to get your flowgraph working, it is probably because your data is no longer frame-synchronized after the mod / demod blocks (yes, that happens, both in simulations and in real-world environments), and error correction codes usually require them to be frame-synchronized.  So, what you will have to look into is frame sync or packet design.

Also, you will have to design your frames with your FEC algorithm in your mind. Simple linear-algebraic algorithms, like Hamming code, will require you to set your frame length to a multiple of some integer. Convolutional code additionally requires you to pad some zeros to your frames, but I forgot the details about it. 

Regards,

Kyeong Su Shin

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보낸 사람: Kyeong Su Shin <ksshin@postech.ac.kr>
보낸 날짜: 2020년 4월 28일 화요일 오전 12:23
받는 사람: Quenten . <quentenswitten@gmail.com>; discuss-gnuradio@gnu.org <discuss-gnuradio@gnu.org>
제목: Re: How to add fec in GMSK

 

Hello Quenten:

You may want to look at some example codes at https://github.com/gnuradio/gnuradio/tree/maint-3.7/gr-fec/examples  (from maint-3.7 branch since you are apparently using GR3.7).  

Please note that most error correction codes require frame synchronization (at least on real-world situations).

Regards,

Kyeong Su Shin

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보낸 사람: Quenten . <quentenswitten@gmail.com> 대신 Discuss-gnuradio <discuss-gnuradio-bounces+ksshin=postech.ac.kr@gnu.org>
보낸 날짜: 2020년 4월 27일 월요일 오후 10:31
받는 사람: discuss-gnuradio@gnu.org <discuss-gnuradio@gnu.org>
제목: 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