3 from gnuradio import gr
4 from gnuradio import audio
5 from gnuradio import trellis
6 from gnuradio import eng_notation
11 def run_test (f,Kb,bitspersymbol,K,dimensionality,constellation,N0,seed,P):
15 src = gr.lfsr_32k_source_s()
16 src_head = gr.head (gr.sizeof_short,Kb/16*P) # packet size in shorts
17 s2fsmi=gr.packed_to_unpacked_ss(bitspersymbol,gr.GR_MSB_FIRST) # unpack shorts to symbols compatible with the FSM input cardinality
18 s2p = gr.stream_to_streams(gr.sizeof_short,P) # serial to parallel
19 enc = trellis.encoder_ss(f,0) # initiali state = 0
20 mod = gr.chunks_to_symbols_sf(constellation,dimensionality)
26 add.append(gr.add_ff())
27 noise.append(gr.noise_source_f(gr.GR_GAUSSIAN,math.sqrt(N0/2),seed))
30 metrics = trellis.metrics_f(f.O(),dimensionality,constellation,trellis.TRELLIS_EUCLIDEAN) # data preprocessing to generate metrics for Viterbi
31 va = trellis.viterbi_s(f,K,0,-1) # Put -1 if the Initial/Final states are not set.
32 p2s = gr.streams_to_stream(gr.sizeof_short,P) # parallel to serial
33 fsmi2s=gr.unpacked_to_packed_ss(bitspersymbol,gr.GR_MSB_FIRST) # pack FSM input symbols to shorts
34 dst = gr.check_lfsr_32k_s()
36 fg.connect (src,src_head,s2fsmi,s2p)
38 fg.connect ((s2p,i),(enc,i),(mod,i))
39 fg.connect ((mod,i),(add[i],0))
40 fg.connect (noise[i],(add[i],1))
41 fg.connect (add[i],(metrics,i))
42 fg.connect ((metrics,i),(va,i),(p2s,i))
43 fg.connect (p2s,fsmi2s,dst)
48 # A bit of cheating: run the program once and print the
49 # final encoder state.
50 # Then put it as the last argument in the viterbi block
51 #print "final state = " , enc.ST()
53 ntotal = dst.ntotal ()
54 nright = dst.nright ()
55 runlength = dst.runlength ()
57 return (ntotal,ntotal-nright)
65 esn0_db=float(args[1]) # Es/No in dB
66 rep=int(args[2]) # number of times the experiment is run to collect enough errors
68 sys.stderr.write ('usage: test_tcm.py fsm_fname Es/No_db repetitions\n')
72 f=trellis.fsm(fname) # get the FSM specification from a file
73 P=4 # how many parallel streams?
74 Kb=1024*16 # packet size in bits (make it multiple of 16 so it can be packed in a short)
75 bitspersymbol = int(round(math.log(f.I())/math.log(2))) # bits per FSM input symbol
76 K=Kb/bitspersymbol # packet size in trellis steps
77 modulation = fsm_utils.psk4 # see fsm_utlis.py for available predefined modulations
78 dimensionality = modulation[0]
79 constellation = modulation[1]
80 if len(constellation)/dimensionality != f.O():
81 sys.stderr.write ('Incompatible FSM output cardinality and modulation size.\n')
83 # calculate average symbol energy
85 for i in range(len(constellation)):
86 Es = Es + constellation[i]**2
87 Es = Es / (len(constellation)/dimensionality)
88 N0=Es/pow(10.0,esn0_db/10.0); # calculate noise variance
90 tot_s=0 # total number of transmitted shorts
91 terr_s=0 # total number of shorts in error
92 terr_p=0 # total number of packets in error
94 (s,e)=run_test(f,Kb,bitspersymbol,K,dimensionality,constellation,N0,-long(666+i),P) # run experiment with different seed to get different noise realizations
97 terr_p=terr_p+(terr_s!=0)
98 if ((i+1)%100==0) : # display progress
99 print i+1,terr_p, '%.2e' % ((1.0*terr_p)/(i+1)),tot_s,terr_s, '%.2e' % ((1.0*terr_s)/tot_s)
100 # estimate of the (short or bit) error rate
101 print rep,terr_p, '%.2e' % ((1.0*terr_p)/(i+1)),tot_s,terr_s, '%.2e' % ((1.0*terr_s)/tot_s)
104 if __name__ == '__main__':