Hello Achilleas, Thanks for your response. I have connected encoder block , it disappeared during editing mail by mistake. Input is in the form of an array of size K and vector2stream feeds encoder bit a time ,so i am using following syntax :
gr_vector_source_s_sptr bit_src = gr_make_vector_source_s(in_bits,false,K );
gr_vector_to_stream_sptr vector2stream = gr_make_vector_to_stream(sizeof(short),K) ------------------------------------------------------------------------------------------------------------
int K=100;
short inputbits[100]={ ....contains bits.... };
std::vector<short> in_bits;
for (int i = 0; i <K ; i++) { // K - no
of bits
in_bits.push_back(inputbits[i]); // input bits
}
std::vector<float> constellation; // BPSK mapping
constellation.push_back(1);
constellation.push_back(-1);
gr_vector_source_s_sptr bit_src = gr_make_vector_source_s(in_bits,false,K );
gr_vector_to_stream_sptr vector2stream= gr_make_vector_to_stream(sizeof(short),K);
// encoder
fsm f=
fsm("../../../gr-trellis/src/examples/fsm_files/awgn1o2_128.fsm");
trellis_encoder_ss_sptr encoder = trellis_make_encoder_ss (f, 0);
// modulate
gr_chunks_to_symbols_sf_sptr mod = gr_make_chunks_to_symbols_sf
(constellation, 1);
// ----------- ideal channel -------------
// decoder
trellis_metric_type_t type= TRELLIS_EUCLIDEAN;
trellis_metrics_f_sptr metrics = trellis_make_metrics_f (f.O(), 1, constellation, type);
trellis_viterbi_s_sptr viterbi =trellis_make_viterbi_s ( f,K, 0,-1);
gr_stream_to_vector_sptr stream2vector= gr_make_stream_to_vector(sizeof(short), K);
d_dst = gr_make_vector_sink_s (K);
connect( bit_src , 0, vector2stream, 0);
connect( vector2stream , 0,encoder, 0);
connect( encoder , 0,mod, 0);
connect(mod, 0,metrics,
0);
connect(metrics, 0, viterbi, 0);
connect( viterbi, 0,stream2vector, 0);
connect(stream2vector, 0, d_dst, 0);
--- On Mon, 19/7/10, Achilleas Anastasopoulos <address@hidden> wrote:
From: Achilleas Anastasopoulos <address@hidden>
Subject: Re: [Discuss-gnuradio] gr-trellis : problem in using viterbi decoder
To: "gnuradio
mailing list" <address@hidden>, address@hidden
Date: Monday, 19 July, 2010, 6:47 PM
I also realized that the way you call
gr_make_vector_source_s(in_bits,false,K );
is incorrect.
I think you have misunderstood what this block does.
You should
use:
gr_make_vector_source_s(in_bits,false,1 );
or simply
gr_make_vector_source_s(in_bits,false);
and you really don't need the vector2stream block.
Achilleas
---------------------
In your code the "encoder" block is not connected to any other block...
It should be:
info bits -> encoder -> modulator -> channel -> metrics -> viterbi
Achilleas
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