Re: [Discuss-gnuradio] Changing code rate (FEC)

On Wed, Aug 26, 2015 at 8:07 PM, Eric Eric <lists@ruby-forum.com> wrote:

Hi,

I would like to be able to change the code rate with PSK and QAM
modulations (e.g QPSK 3/4, 16QAM 1/2). I was thinking of using a FEC
encoder/decoder as you can see in the attached files but it doesn't
really work. I'm trying to send a video file and I would like to be able
to read the received video. What can I do to make it work or is there
another way to change the coding rate?

Thanks

Attachments:
http://www.ruby-forum.com/attachment/11055/fec1.jpg
http://www.ruby-forum.com/attachment/11056/fec2.jpg
http://www.ruby-forum.com/attachment/11057/fec3.jpg

Dynamics here haven't been tested much. A lot of the codes defined now are single-purpose because there's a lot of initialization and setup that occurs that might interfere with the running of things. It'd be interesting to see where different codes can be modified live. But for the CC encoder/decoder you're using, look at the man page:

http://gnuradio.org/doc/doxygen/classgr_1_1fec_1_1code_1_1cc__decoder.html

That code is highly optimized to do that one rate and K factor that it does.

You might have better luck making multiple variables and switching them in and out of the FEC extended encoder/decoder blocks. I feel we might have to do something to invalidate any data due to changes in cipher/plain text, though.

Tom