3 from gnuradio import gr
4 from gnuradio import audio
5 from gnuradio import trellis
6 from gnuradio import eng_notation
12 def run_test (fo,fi,interleaver,Kb,bitspersymbol,K,dimensionality,constellation,N0,seed):
17 src = gr.lfsr_32k_source_s()
18 src_head = gr.head (gr.sizeof_short,Kb/16) # packet size in shorts
19 s2fsmi = gr.packed_to_unpacked_ss(bitspersymbol,gr.GR_MSB_FIRST) # unpack shorts to symbols compatible with the outer FSM input cardinality
20 enc_out = trellis.encoder_ss(fo,0) # initial state = 0
21 inter = trellis.permutation(interleaver.K(),interleaver.INTER(),1,gr.sizeof_short)
22 enc_in = trellis.encoder_ss(fi,0) # initial state = 0
23 mod = gr.chunks_to_symbols_sf(constellation,dimensionality)
27 noise = gr.noise_source_f(gr.GR_GAUSSIAN,math.sqrt(N0/2),seed)
30 metrics_in = trellis.metrics_f(fi.O(),dimensionality,constellation,trellis.TRELLIS_EUCLIDEAN) # data preprocessing to generate metrics for innner Viterbi
31 va_in = trellis.viterbi_s(fi,K,0,-1) # Put -1 if the Initial/Final states are not set.
32 deinter = trellis.permutation(interleaver.K(),interleaver.DEINTER(),1,gr.sizeof_short)
33 metrics_out = trellis.metrics_s(fo.O(),1,[0,1,2,3],trellis.TRELLIS_HARD_SYMBOL) # data preprocessing to generate metrics for outer Viterbi (hard decisions)
34 va_out = trellis.viterbi_s(fo,K,0,-1) # Put -1 if the Initial/Final states are not set.
35 fsmi2s = gr.unpacked_to_packed_ss(bitspersymbol,gr.GR_MSB_FIRST) # pack FSM input symbols to shorts
36 dst = gr.check_lfsr_32k_s()
38 fg.connect (src,src_head,s2fsmi,enc_out,inter,enc_in,mod)
39 fg.connect (mod,(add,0))
40 fg.connect (noise,(add,1))
41 fg.connect (add,metrics_in)
42 fg.connect (metrics_in,va_in,deinter,metrics_out,va_out,fsmi2s,dst)
46 ntotal = dst.ntotal ()
47 nright = dst.nright ()
48 runlength = dst.runlength ()
49 return (ntotal,ntotal-nright)
57 esn0_db=float(args[2]) # Es/No in dB
58 rep=int(args[3]) # number of times the experiment is run to collect enough errors
60 sys.stderr.write ('usage: test_tcm.py fsm_name_out fsm_fname_in Es/No_db repetitions\n')
64 Kb=1024*16 # packet size in bits (make it multiple of 16 so it can be packed in a short)
65 fo=trellis.fsm(fname_out) # get the outer FSM specification from a file
66 fi=trellis.fsm(fname_in) # get the innner FSM specification from a file
67 bitspersymbol = int(round(math.log(fo.I())/math.log(2))) # bits per FSM input symbol
69 sys.stderr.write ('Incompatible cardinality between outer and inner FSM.\n')
71 K=Kb/bitspersymbol # packet size in trellis steps
72 interleaver=trellis.interleaver(K,666) # construct a random interleaver
73 modulation = fsm_utils.psk8 # see fsm_utlis.py for available predefined modulations
74 dimensionality = modulation[0]
75 constellation = modulation[1]
76 if len(constellation)/dimensionality != fi.O():
77 sys.stderr.write ('Incompatible FSM output cardinality and modulation size.\n')
79 # calculate average symbol energy
81 for i in range(len(constellation)):
82 Es = Es + constellation[i]**2
83 Es = Es / (len(constellation)/dimensionality)
84 N0=Es/pow(10.0,esn0_db/10.0); # calculate noise variance
86 tot_s=0 # total number of transmitted shorts
87 terr_s=0 # total number of shorts in error
88 terr_p=0 # total number of packets in error
90 (s,e)=run_test(fo,fi,interleaver,Kb,bitspersymbol,K,dimensionality,constellation,N0,-long(666+i)) # run experiment with different seed to get different noise realizations
93 terr_p=terr_p+(terr_s!=0)
94 if ((i+1)%100==0) : # display progress
95 print i+1,terr_p, '%.2e' % ((1.0*terr_p)/(i+1)),tot_s,terr_s, '%.2e' % ((1.0*terr_s)/tot_s)
96 # estimate of the (short or bit) error rate
97 print rep,terr_p, '%.2e' % ((1.0*terr_p)/(i+1)),tot_s,terr_s, '%.2e' % ((1.0*terr_s)/tot_s)
100 if __name__ == '__main__':