I applied trellis in benchmark_tx2 and rx2 using dbpsk2.
I have modified the dbpsk2.py file according to the test_tcm_bit.py.
# turn bytes into k-bit vectors
self.bytes2chunks = \
gr.packed_to_unpacked_bb(self.bits_per_symbol(), gr.GR_MSB_FIRST)
#add the error correlation code
fsm = trellis.fsm("/home/symbol/gnuradio/gr-trellis/src/examples/fsm_files/awgn1o2_128.fsm")
self.trellis_enc = trellis.encoder_bb(fsm, 0);
#gray code
self.symbol_mapper = gr.map_bb(psk.binary_to_gray[arity])
self.diffenc = gr.diff_encoder_bb(arity)
self.chunks2symbols = gr.chunks_to_symbols_bc(psk.constellation[arity])
# pulse shaping filter
nfilts = 32
ntaps = nfilts * 11 * int(self._samples_per_symbol) # make nfilts filters of ntaps each
self.rrc_taps = gr.firdes.root_raised_cosine(
nfilts, # gain
nfilts, # sampling rate based on 32 filters in resampler
1.0, # symbol rate
self._excess_bw, # excess bandwidth (roll-off factor)
ntaps)
self.rrc_filter = gr.pfb_arb_resampler_ccf(self._samples_per_symbol, self.rrc_taps)
# Connect
self.connect(self,
self.bytes2chunks, self.symbol_mapper, self.trellis_enc,
self.diffenc, self.chunks2symbols, self.rrc_filter, self)
On the RX side:
self.phase_recov = gr.costas_loop_cc(self._phase_alpha,
self._phase_beta,
fmax, fmin, arity)
# Do differential decoding based on phase change of symbols
self.diffdec = gr.diff_phasor_cc()
#the error correlation code
fsm = trellis.fsm("/home/symbol/gnuradio/gr-trellis/src/examples/fsm_files/awgn1o2_128.fsm")
metrics = trellis.metrics_c(fsm.O(), arity, psk.constellation[arity], trellis.TRELLIS_EUCLIDEAN)
va = trellis.viterbi_b(fsm, 1520, 0, -1)
self.symbol_mapper = gr.map_bb(psk.gray_to_binary[arity])
# unpack the k bit vector into a stream of bits
self.unpack = gr.unpack_k_bits_bb(self.bits_per_symbol())
# Connect
self.connect(self, self.agc, self.freq_recov, self.time_recov, self.phase_recov,
self.diffdec, metrics, va, self.symbol_mapper, self.unpack, self)
I can not get any packets on the receiver side. If I remove the trellis encode and decode block, everything works fine.
There must be some problems with the use of trellis blocks. Could some one give me any clue?
Any help is appreciated!
Best,
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