Re: [Discuss-gnuradio] convolutional code via gr-trellis

[Achilleas Anastasopoulos]

vincenzo,

this is NOT correct:

what is the purpose of the repacker?

the encoder in your case outputs bytes with values in {0,1,2,3}
these need to be mapped to your constellation (QPSK), not to be packet 
into bytes.

I am surprised that this does not result in an error
within the chunk_to_symbols block...???!!!

f=trellis.fsm("/root/MAIN/soft/gnuradio/gr-mystuff/finite_state_machine")
file_chunker=gr.packed_to_unpacked_bb(1,gr.GR_LSB_FIRST)
convolutional_encoder = trellis.encoder_bb(f,0)
self.connect(file_source_bytewise,file_chunker,convolutional_encoder,symbol_mapper)



Achilleas





---------------

Hi, thanks again Achilleas for suggestions and help,

so far I've tried this for the convolutional 1,2 code.

this is the file for setting up the finite state machine

2 4 4

0 2
0 2
1 3
1 3

0 3
3 0
2 1
1 2

does it make sense?


and this is the code for connecting the encoder into the flow grpah


        file_chunker=gr.packed_to_unpacked_bb(1,gr.GR_LSB_FIRST)


f=trellis.fsm("/root/MAIN/soft/gnuradio/gr-mystuff/finite_state_machine")
        repacker=gr.packed_to_unpacked_bb(2,gr.GR_LSB_FIRST)
        convolutional_encoder = trellis.encoder_bb(f,0)

self.connect(file_source_bytewise,file_chunker,convolutional_encoder,repacker,symbol_mapper)


this bringrs out a spectrum picture which is significantly different
than the one without the encoder... much more "squared"
am I going the right way?