RE: [Discuss-gnuradio] How to decode the convolutional code, in the GRC

[intermilan]

Achilleas:

     What I want to do is want to see the BER when the convolutional code is used in different modulator in the GRC,but I had not put the noise source in the flow graph so there is no noise between the modulator and demodulator.
     Besides,in my opinion, we can consider the packet_encoder and packet_decoder block is part of the modulation.In other words,in the flow graph I mentioned ,the data input the packet_encoder is the same as the packet_decoder block(because I did not put the noise block between the modulator and demodulator ).
     But I still not understand how to set the parameters in the viterbi block in this case, particularly the  parameter constellation if I do not use the chunks_to_symbols block.
    Thanks for your help.

inter

> Date: Fri, 11 Mar 2011 17:33:25 -0500
> From: address@hidden
> To: address@hidden; address@hidden
> Subject: RE: [Discuss-gnuradio] How to decode the convolutional code, in the GRC
>
>
> inter,
>
> think of whatever is AFTER the trellis encoder and BEFORE the viterbi
> decoder as an equivalent channel.
>
> What is the equivalent channel in your case?
> What is its input alphabet? what is its output alphabet?
>
> From your description, it seems that the input alphabet is the same as
> the output alphabet of your FSM.
>
> I am not familiar with the block "packet decoder" so i don't know what
> it outputs, but whatever it is it should be the output alphabet of your
> "equivalent" channel.
>
> Once you figure out these things it will be straightforward to see what
> the viterbi block should be...
> If you gather these pieces of information and still don't see how to
> implement the viterbi decoder let me know and i will provide further help.
>
> Achilleas