Re: [Discuss-gnuradio] gr-trellis: convenc and viterbi with own mapper/de-mapper

[Achilleas Anastasopoulos]

Jonas,

one idea is to add a method "set_K(K)" to the viterbi class.
This method sets d_K AND calls the set_multiple() method with the new value.
This method will be called from , say , the python code.

Achilleas


On Sat, Oct 23, 2010 at 1:59 PM, "Jonas M. Börner"
<address@hidden> wrote:
> Dear Achilleas,
>
> I use your Viterbi implementation in a dynamic ressource allocation framework 
> for OFDM. Data is processed frame-wise and in general, every frame carries a 
> different number of coded bits. So I need to tell the Viterbi the number of 
> trellis steps in each step. As far as I can see, there is no way yet to use 
> this block like this since I have to specify the number of trellis steps at 
> initialization. I tried to feed a integer source to the block and read d_K in 
> general_work() from where but the main problem is, that I cannot reset the 
> set_output_multiple thing. If I don't use set_output_multiple function the 
> assertion that noutput_items has to be integer multiple of d_K fails.
>
> I'd appreciate any hints you can give me. :)
>
> Jonas
>
> Am 19.08.2010 um 10:19 schrieb Achilleas Anastasopoulos:
>
>> Jonas,
>>
>> there is a very extensive doc file in gr-trellis that hopefully
>> answers your questions,
>> as well as a lot of examples.
>> Please read it and let me know if you still have questions about it.
>> BTW: your issue has nothing to do with truncation as was suggested in a 
>> reply.
>>
>> In short: one way to implement your system is to mapp the encoded
>> symbols directly to
>> QPSK symbols (essentially this is what you are doing!) and thus
>> produce 5 demodulated symbols
>> that you will feed in the VA.
>>
>> Achilleas
>