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

[Jonas M. Börner]

Hi all,

I am trying to use the convolutional encoder and Viterbi provided by the 
gr-trellis class within another environment. I have my own mapper and de-mapper 
blocks which I want to use. So I tried to use the feed the viterbi_combined 
with this arguments:

va_combined = 
trellis.viterbi_combined_fb(fo,nsymbols,0,-1,1,[-1,1],trellis.TRELLIS_EUCLIDEAN)

My de-mapper outputs soft bits between -1 and +1. Here is an example output of 
my test script:

data:           [0, 1, 1, 0, 0]
encoded:        (0, 3, 2, 2, 0)
unpacked:       (0, 0, 1, 1, 1, 0, 1, 0, 0, 0)
modulated:      ((1+0j), (1+0j), (-1+0j), (-1+0j), (-1+0j), (1+0j), (-1+0j), 
(1+0j), (1+0j), (1+0j))
demodulated:    (-1.0, -1.0, 1.0, 1.0, 1.0, -1.0, 1.0, -1.0, -1.0, -1.0)
decoded:        (0, 0, 1, 0, 0, 1, 0, 1, 0, 1)

Another thing I don't understand is why the decoder outputs 10 values instead 
of 5. I would be glad if someone told me what I am doing wrong.

Regards,
        Jonas