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 (f,Kb,bitspersymbol,K,dimensionality,constellation,N0,seed):
18 #for i in range(Kb-1*16): # last 16 bits = 0 to drive the final state to 0
19 #packet[i] = random.randint(0, 1) # random 0s and 1s
20 #src = gr.vector_source_s(packet,False)
21 src = gr.lfsr_32k_source_s()
22 src_head = gr.head (gr.sizeof_short,Kb/16) # packet size in shorts
23 #b2s = gr.unpacked_to_packed_ss(1,gr.GR_MSB_FIRST) # pack bits in shorts
24 s2fsmi = gr.packed_to_unpacked_ss(bitspersymbol,gr.GR_MSB_FIRST) # unpack shorts to symbols compatible with the FSM input cardinality
25 enc = trellis.encoder_ss(f,0) # initial state = 0
26 mod = gr.chunks_to_symbols_sf(constellation,dimensionality)
30 noise = gr.noise_source_f(gr.GR_GAUSSIAN,math.sqrt(N0/2),seed)
33 metrics = trellis.metrics_f(f.O(),dimensionality,constellation,trellis.TRELLIS_EUCLIDEAN) # data preprocessing to generate metrics for Viterbi
34 va = trellis.viterbi_s(f,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 #s2b = gr.packed_to_unpacked_ss(1,gr.GR_MSB_FIRST) # unpack shorts to bits
37 #dst = gr.vector_sink_s();
38 dst = gr.check_lfsr_32k_s()
41 tb.connect (src,src_head,s2fsmi,enc,mod)
42 #tb.connect (src,b2s,s2fsmi,enc,mod)
43 tb.connect (mod,(add,0))
44 tb.connect (noise,(add,1))
45 tb.connect (add,metrics)
46 tb.connect (metrics,va,fsmi2s,dst)
47 #tb.connect (metrics,va,fsmi2s,s2b,dst)
52 # A bit of cheating: run the program once and print the
53 # final encoder state..
54 # Then put it as the last argument in the viterbi block
55 #print "final state = " , enc.ST()
57 ntotal = dst.ntotal ()
58 nright = dst.nright ()
59 runlength = dst.runlength ()
61 #if len(dst.data()) != ntotal:
62 #print "Error: not enough data\n"
64 #for i in range(ntotal):
65 #if packet[i]==dst.data()[i]:
69 return (ntotal,ntotal-nright)
77 esn0_db=float(args[0]) # Es/No in dB
78 rep=int(args[1]) # number of times the experiment is run to collect enough errors
80 sys.stderr.write ('usage: test_tcm2.py Es/No_db repetitions\n')
84 f=trellis.fsm(1,2,[5,7]) # generate FSM specification from the generator matrix
85 Kb=1024*16 # packet size in bits (make it multiple of 16 so it can be packed in a short)
86 bitspersymbol = int(round(math.log(f.I())/math.log(2))) # bits per FSM input symbol
87 K=Kb/bitspersymbol # packet size in trellis steps
88 modulation = fsm_utils.psk4 # see fsm_utlis.py for available predefined modulations
89 dimensionality = modulation[0]
90 constellation = modulation[1]
91 if len(constellation)/dimensionality != f.O():
92 sys.stderr.write ('Incompatible FSM output cardinality and modulation size.\n')
94 # calculate average symbol energy
96 for i in range(len(constellation)):
97 Es = Es + constellation[i]**2
98 Es = Es / (len(constellation)/dimensionality)
99 N0=Es/pow(10.0,esn0_db/10.0); # calculate noise variance
101 tot_s=0 # total number of transmitted shorts
102 terr_s=0 # total number of shorts in error
103 terr_p=0 # total number of packets in error
105 (s,e)=run_test(f,Kb,bitspersymbol,K,dimensionality,constellation,N0,-long(666+i)) # run experiment with different seed to get different noise realizations
108 terr_p=terr_p+(terr_s!=0)
109 if ((i+1)%100==0) : # display progress
110 print i+1,terr_p, '%.2e' % ((1.0*terr_p)/(i+1)),tot_s,terr_s, '%.2e' % ((1.0*terr_s)/tot_s)
111 # estimate of the (short or bit) error rate
112 print rep,terr_p, '%.2e' % ((1.0*terr_p)/(i+1)),tot_s,terr_s, '%.2e' % ((1.0*terr_s)/tot_s)
115 if __name__ == '__main__':