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Diffstat (limited to 'gr-trellis/doc/test_viterbi_equalization1.py.xml')
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1 files changed, 105 insertions, 0 deletions
diff --git a/gr-trellis/doc/test_viterbi_equalization1.py.xml b/gr-trellis/doc/test_viterbi_equalization1.py.xml new file mode 100644 index 000000000..cb13772fc --- /dev/null +++ b/gr-trellis/doc/test_viterbi_equalization1.py.xml @@ -0,0 +1,105 @@ +<?xml version="1.0" encoding="ISO-8859-1"?> +<programlisting> + 1 #!/usr/bin/env python + 2 + 3 from gnuradio import gr + 4 from gnuradio import audio + 5 from gnuradio import trellis + 6 from gnuradio import eng_notation + 7 import math + 8 import sys + 9 import random + 10 import fsm_utils + 11 + 12 def run_test (f,Kb,bitspersymbol,K,channel,modulation,dimensionality,tot_constellation,N0,seed): + 13 fg = gr.flow_graph () + 14 L = len(channel) + 15 + 16 # TX + 17 # this for loop is TOO slow in python!!! + 18 packet = [0]*(K+2*L) + 19 random.seed(seed) + 20 for i in range(len(packet)): + 21 packet[i] = random.randint(0, 2**bitspersymbol - 1) # random symbols + 22 for i in range(L): # first/last L symbols set to 0 + 23 packet[i] = 0 + 24 packet[len(packet)-i-1] = 0 + 25 src = gr.vector_source_s(packet,False) + 26 mod = gr.chunks_to_symbols_sf(modulation[1],modulation[0]) + 27 + 28 # CHANNEL + 29 isi = gr.fir_filter_fff(1,channel) + 30 add = gr.add_ff() + 31 noise = gr.noise_source_f(gr.GR_GAUSSIAN,math.sqrt(N0/2),seed) + 32 + 33 # RX + 34 skip = gr.skiphead(gr.sizeof_float, L) # skip the first L samples since you know they are coming from the L zero symbols + 35 #metrics = trellis.metrics_f(f.O(),dimensionality,tot_constellation,trellis.TRELLIS_EUCLIDEAN) # data preprocessing to generate metrics for Viterbi + 36 #va = trellis.viterbi_s(f,K+L,-1,0) # Put -1 if the Initial/Final states are not set. + 37 va = trellis.viterbi_combined_s(f,K+L,0,0,dimensionality,tot_constellation,trellis.TRELLIS_EUCLIDEAN) # using viterbi_combined_s instead of metrics_f/viterbi_s allows larger packet lengths because metrics_f is complaining for not being able to allocate large buffers. This is due to the large f.O() in this application... + 38 dst = gr.vector_sink_s() + 39 + 40 fg.connect (src,mod) + 41 fg.connect (mod,isi,(add,0)) + 42 fg.connect (noise,(add,1)) + 43 #fg.connect (add,metrics) + 44 #fg.connect (metrics,va,dst) + 45 fg.connect (add,skip,va,dst) + 46 + 47 fg.run() + 48 + 49 data = dst.data() + 50 ntotal = len(data) - L + 51 nright=0 + 52 for i in range(ntotal): + 53 if packet[i+L]==data[i]: + 54 nright=nright+1 + 55 #else: + 56 #print "Error in ", i + 57 + 58 return (ntotal,ntotal-nright) + 59 + 60 + 61 def main(args): + 62 nargs = len (args) + 63 if nargs == 2: + 64 esn0_db=float(args[0]) + 65 rep=int(args[1]) + 66 else: + 67 sys.stderr.write ('usage: test_viterbi_equalization1.py Es/No_db repetitions\n') + 68 sys.exit (1) + 69 + 70 # system parameters + 71 Kb=2048 # packet size in bits + 72 modulation = fsm_utils.pam4 # see fsm_utlis.py for available predefined modulations + 73 channel = fsm_utils.c_channel # see fsm_utlis.py for available predefined test channels + 74 f=trellis.fsm(len(modulation[1]),len(channel)) # generate the FSM automatically + 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 + 78 tot_channel = fsm_utils.make_isi_lookup(modulation,channel,True) # generate the lookup table (normalize energy to 1) + 79 dimensionality = tot_channel[0] + 80 tot_constellation = tot_channel[1] + 81 N0=pow(10.0,-esn0_db/10.0); # noise variance + 82 if len(tot_constellation)/dimensionality != f.O(): + 83 sys.stderr.write ('Incompatible FSM output cardinality and lookup table size.\n') + 84 sys.exit (1) + 85 + 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 + 89 + 90 for i in range(rep): + 91 (s,e)=run_test(f,Kb,bitspersymbol,K,channel,modulation,dimensionality,tot_constellation,N0,-long(666+i)) # run experiment with different seed to get different data and noise realizations + 92 tot_s=tot_s+s + 93 terr_s=terr_s+e + 94 terr_p=terr_p+(terr_s!=0) + 95 if ((i+1)%100==0) : # display progress + 96 print i+1,terr_p, '%.2e' % ((1.0*terr_p)/(i+1)),tot_s,terr_s, '%.2e' % ((1.0*terr_s)/tot_s) + 97 # estimate of the (short or symbol) error rate + 98 print rep,terr_p, '%.2e' % ((1.0*terr_p)/(i+1)),tot_s,terr_s, '%.2e' % ((1.0*terr_s)/tot_s) + 99 +100 +101 if __name__ == '__main__': +102 main (sys.argv[1:]) +</programlisting> |