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Re: [Discuss-gnuradio] gr-trellis convolutional coder FSM
From: |
Clemens Hopfer |
Subject: |
Re: [Discuss-gnuradio] gr-trellis convolutional coder FSM |
Date: |
Tue, 19 Jun 2012 00:12:24 +0200 |
User-agent: |
KMail/1.13.6 (Linux/2.6.38-15-generic-pae; KDE/4.6.5; i686; ; ) |
Hello Achilleas,
thanks for your reply,
On Tuesday 12 June 2012 19:53:10 Achilleas Anastasopoulos wrote:
> puncturing is not part of the FSM class.
ok, thanks for the clarification, that caused the biggest confusion.
> You can implement it as a simple memoryless device:
> eg, if i want to puncture every third bit, then the device
> accepts 3bits as inputs and outputs the first two.
Ok, I didn't really like to map each bit to a byte, but the data rate I want
to use shouldn't be that high to get into performance problems.
> If you can give me more details on what exactly you want to
> implement i may be able to help you out.
I actually want to implement the inner coder used by DVB-S (ETSI EN 300 421,
4.4.3).
But it's just a hobbyist project, so I'm not in a hurry implementing it.
> Similraly, if you let me know which part of the FSM/trellis documentation
> is hard to read, hopefully i will be able to help.
I'm currently working on my BSc and haven't really done a lot with state
machines yet, so working with machine alphabets is pretty new for me, but I
guess I figured it out by now.
Again, thanks for your reply.
I'm pretty busy right now, but in about 2 weeks I'll have enough time to work
on it again.
Best regards,
Clemens
> --------------------
> Hi,
>
> I'm working on a modulator using a punctured (non-recursive) convolutional
> coder based on a 1/2 rate mother code with length 7.
>
> However I find the documentation of gr-trellis pretty hard to read, I don't
> really understand how punctuation should actually be implemented.
>
> Are there any additional documents or papers on designing the FSM of a
> convolutional coder?
>
> Thanks,
> Clemens
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