I want to use convolution code to transmit packet over USRP. So I ended up modifying the generic_mod_demod in digital.
The original flow graph was Tx packed_to_unpacked(bits_per_symbol) ---> gray_encoder ---> differential_encoder ---> chunks_to_symbol(constellation) ---> rrc_filter ---> USRP Rx USRP ---> fll_band_edge ---> pfb_clock_sync ---> (constellation_receiver, 0) ---> demod_pkts Now I have modified it to the following. Tx packed_to_unpacked(bits_per_trellis_input) ---> trellis_encoder(fsm) ---> chunnks_to_symbol(constellatin) ---> rrc_filter ---> USRP Rx USRP ---> fll_band_edge ---> pfb_clock_sync ---> (constelllation_receiver, 4)(symbol) ---> viterbi_combined ---> demod_pkts I find this structure ends up in more errors than before. ( almost all errors ) 1. Does the packet size at the output of pkt.py has anything to do with the block_length in viterbi_combined? 2. Will it make any difference if I specify the starting and ending states?? -- Manu T S
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