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From: amlmadrid on 4 Sep 2009 15:58
Hi all,

does anyone know how can I do the viterbi decoding of a very large bit
stream by spliting it up in blocks? So, the output of the decoded stream of
each block should be concatenated to the output of the next block. I have
seen that it is a very common problem but none says how to solve it. The
thing is that if I try to decode a very big string of bits, the metrics
overflow. By the way, if someone has access to this document, it would be
very appreciated if you could email it me... (amlmadrid@ yahoo.es)

http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=176168

thanks a lot :)


From: Eric Jacobsen on 4 Sep 2009 20:10
On 9/4/2009 12:58 PM, amlmadrid wrote:
> Hi all,
>
> does anyone know how can I do the viterbi decoding of a very large bit
> stream by spliting it up in blocks? So, the output of the decoded stream of
> each block should be concatenated to the output of the next block. I have
> seen that it is a very common problem but none says how to solve it. The
> thing is that if I try to decode a very big string of bits, the metrics
> overflow. By the way, if someone has access to this document, it would be
> very appreciated if you could email it me... (amlmadrid@ yahoo.es)
>
> http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=176168
>
> thanks a lot :)
>
>

Most decoder don't work on the full message length, and many can't since
often the encoded stream is nearly continuous (e.g., video broadcasts,
stuff like that).

Search on "traceback depth" or "traceback memory" in the context of
Viterbi decoders and see what you can find. I'll bet you'll get your
answers that way.

--
Eric Jacobsen
Minister of Algorithms
Abineau Communications
http://www.abineau.com
From: Vladimir Vassilevsky on 6 Sep 2009 16:50


amlmadrid wrote:

> The thing is that if I try to decode a very big string of bits, the metrics
> overflow.

Subtract the least weight from all paths at every step of the algorithm.


Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
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