Gr-trellis ; convolutional code and convolutionnal interleaver

Gr-trellis ; convolutional code and convolutionnal interleaver.

Hi,

I’m trying to design an error correction flow graph that would use a
convolutional encoder and a convolutional interleaver. I searched in
gr-trellis for the appropriate blocks, but I have a bunch of questions
about how to use them.

About the convolutional interleaver.
Trellis.interleaver needs a specification file. Where can I find an
example of this specification file? The best would be a file specifying
a
convolutional interleaving.

About Viterbi decoder
I wrote the following python file that should encode a stream of bits
and
decode it using Viterbi algorithm. Unfortunately, my inputs and outputs
are different. What did I do wrong?

Thanks
Axel

class top(gr.top_block):
def init(self):
gr.top_block.init(self)

constel= (2,[0, 0, 0, 1, 1, 0, 1, 1])
f=trellis.fsm("/home/Axel/Desktop/Testgnuradio/FSM_Codeur2.fsm")
self.src_data =

(0,0,1,0,0,1,1,0,1,0,1,1,1,0,1,0,1,1,0,0,1,0,0,1,1,0,1,1,0,1,1,0,1,0,0,1,1,0,0,0,1,1,1,0,1,0,1,1,0,0,1,0,0,1,1,0,1,1,0,1,1,0,1,0,0,1,1,0,0,0,1,1,1,0,1,0,1,1,0,0,1,0,0,1,1,0,1,1,0,1,1,0,1,0,0,1,1,0,0,0,1,1,1,0,1,0,1,1,0,0,1,0,0,1,1,0,1,1,0,1,1,0,1,0,0,1,1,0,0,0,1,1,1,0,1,0,1,1,0,0,1,0,0,1,1,0,1,1,0,1,1,0,1,0,0,1,1,0,0,0,1,1,1,0,1,0,1,1,0,0,1,0,0,1,1,0,1,1,0,1,)

self.in_data = gr.vector_source_s (self.src_data)
self.enc = trellis.encoder_ss(f,0) # initial state = 0
#self.mod = gr.chunks_to_symbols_sf(constel[1],constel[0])

self.metrics =

trellis.metrics_s(f.O(),1,[0,1,2,3],trellis.TRELLIS_HARD_SYMBOL)
self.va = trellis.viterbi_s(f,2,0,-1) # Put -1 if the Initial/Final
states are not set.
#self.va
=trellis.viterbi_combined_s(f,K+L,0,0,dimensionality,tot_constellation,trellis.TRELLIS_EUCLIDEAN)
self.sink1= gr.vector_sink_s()
self.sink2= gr.vector_sink_s()

self.connect

(self.in_data,self.enc,self.metrics,self.va,self.sink2)#,self.metrics,self.va)
self.connect (self.in_data,self.sink1)
def print_out(self):
print “in”,self.sink1.data()
print “out”,self.sink2.data()

if name == ‘main’:
try:
tb = top()
tb.run()
tb.print_out()

except KeyboardInterrupt:
pass

(FSM_codeur2.fsm = )
2 4 4

0 2
0 2
1 3
1 3

0 3
3 0
1 2
2 1

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