[Discuss-gnuradio] convolutional code via gr-trellis

[Vincenzo Pellegrini]

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?



what about the viterbi decoder?
I've got wrong data size errors when connecting 
 a bit by bit stream obtained from demodulated symbols  to
trellis.metrics, this way in the Rx chain:

symbols_to_bytes=gr.constellation_decoder_cb(constellation,constellation_bytes) 
       
        print constellation_bytes

        repacker_rx_1=gr.packed_to_unpacked_bb(1,gr.GR_LSB_FIRST)

        K=1
        metrics =
trellis.metrics_c(f.O(),3,constellation,trellis.TRELLIS_EUCLIDEAN)
        viterbi_decoder = trellis.viterbi_b(f,K,0,-1)



self.connect(gain,series_to_parallel_2,direct_fft,parallel_to_series_2,symbols_to_bytes,repacker_rx_1,metrics,viterbi_decoder,file_repacker,file_sink)


many thanks

vincenzo