1 <?xml version="1.0" encoding="ISO-8859-1"?>
3 1 #!/usr/bin/env python
5 3 from gnuradio import gr
6 4 from gnuradio import audio
7 5 from gnuradio import trellis
8 6 from gnuradio import eng_notation
14 12 def run_test (f,Kb,bitspersymbol,K,dimensionality,constellation,N0,seed):
15 13 tb = gr.top_block ()
18 16 src = gr.lfsr_32k_source_s()
19 17 src_head = gr.head (gr.sizeof_short,Kb/16) # packet size in shorts
20 18 s2fsmi = gr.packed_to_unpacked_ss(bitspersymbol,gr.GR_MSB_FIRST) # unpack shorts to symbols compatible with the FSM input cardinality
21 19 enc = trellis.encoder_ss(f,0) # initial state = 0
22 20 mod = gr.chunks_to_symbols_sf(constellation,dimensionality)
26 24 noise = gr.noise_source_f(gr.GR_GAUSSIAN,math.sqrt(N0/2),seed)
29 27 metrics = trellis.metrics_f(f.O(),dimensionality,constellation,trellis.TRELLIS_EUCLIDEAN) # data preprocessing to generate metrics for Viterbi
30 28 va = trellis.viterbi_s(f,K,0,-1) # Put -1 if the Initial/Final states are not set.
31 29 fsmi2s = gr.unpacked_to_packed_ss(bitspersymbol,gr.GR_MSB_FIRST) # pack FSM input symbols to shorts
32 30 dst = gr.check_lfsr_32k_s();
34 32 tb.connect (src,src_head,s2fsmi,enc,mod)
35 33 tb.connect (mod,(add,0))
36 34 tb.connect (noise,(add,1))
37 35 tb.connect (add,metrics)
38 36 tb.connect (metrics,va,fsmi2s,dst)
42 40 # A bit of cheating: run the program once and print the
43 41 # final encoder state.
44 42 # Then put it as the last argument in the viterbi block
45 43 #print "final state = " , enc.ST()
47 45 ntotal = dst.ntotal ()
48 46 nright = dst.nright ()
49 47 runlength = dst.runlength ()
50 48 return (ntotal,ntotal-nright)
57 55 esn0_db=float(args[1]) # Es/No in dB
58 56 rep=int(args[2]) # number of times the experiment is run to collect enough errors
60 58 sys.stderr.write ('usage: test_tcm.py fsm_fname Es/No_db repetitions\n')
63 61 # system parameters
64 62 f=trellis.fsm(fname) # get the FSM specification from a file
65 63 Kb=1024*16 # packet size in bits (make it multiple of 16 so it can be packed in a short)
66 64 bitspersymbol = int(round(math.log(f.I())/math.log(2))) # bits per FSM input symbol
67 65 K=Kb/bitspersymbol # packet size in trellis steps
68 66 modulation = fsm_utils.psk4 # see fsm_utlis.py for available predefined modulations
69 67 dimensionality = modulation[0]
70 68 constellation = modulation[1]
71 69 if len(constellation)/dimensionality != f.O():
72 70 sys.stderr.write ('Incompatible FSM output cardinality and modulation size.\n')
74 72 # calculate average symbol energy
76 74 for i in range(len(constellation)):
77 75 Es = Es + constellation[i]**2
78 76 Es = Es / (len(constellation)/dimensionality)
79 77 N0=Es/pow(10.0,esn0_db/10.0); # noise variance
83 81 for i in range(rep):
84 82 (s,e)=run_test(f,Kb,bitspersymbol,K,dimensionality,constellation,N0,-long(666+i)) # run experiment with different seed to get different noise realizations
88 86 print i,s,e,tot_s,terr_s, '%e' % ((1.0*terr_s)/tot_s)
89 87 # estimate of the (short) error rate
90 88 print tot_s,terr_s, '%e' % ((1.0*terr_s)/tot_s)
93 91 if __name__ == '__main__':
94 92 main (sys.argv[1:])