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#!/usr/bin/env python
from gnuradio import gr
from gnuradio import audio
from gnuradio import trellis
from gnuradio import eng_notation
import math
import sys
import random
import fsm_utils
def run_test (f,Kb,bitspersymbol,K,dimensionality,constellation,N0,seed):
fg = gr.flow_graph ()
# TX
src = gr.lfsr_32k_source_s()
src_head = gr.head (gr.sizeof_short,Kb/16) # packet size in shorts
s2fsmi = gr.packed_to_unpacked_ss(bitspersymbol,gr.GR_MSB_FIRST) # unpack shorts to symbols compatible with the FSM input cardinality
enc = trellis.encoder_ss(f,0) # initial state = 0
mod = gr.chunks_to_symbols_sf(constellation,dimensionality)
# CHANNEL
add = gr.add_ff()
noise = gr.noise_source_f(gr.GR_GAUSSIAN,math.sqrt(N0/2),seed)
# RX
metrics = trellis.metrics_f(f.O(),dimensionality,constellation,trellis.TRELLIS_EUCLIDEAN) # data preprocessing to generate metrics for Viterbi
va = trellis.viterbi_s(f,K,0,-1) # Put -1 if the Initial/Final states are not set.
fsmi2s = gr.unpacked_to_packed_ss(bitspersymbol,gr.GR_MSB_FIRST) # pack FSM input symbols to shorts
dst = gr.check_lfsr_32k_s();
fg.connect (src,src_head,s2fsmi,enc,mod)
fg.connect (mod,(add,0))
fg.connect (noise,(add,1))
fg.connect (add,metrics)
fg.connect (metrics,va,fsmi2s,dst)
fg.run()
# A bit of cheating: run the program once and print the
# final encoder state.
# Then put it as the last argument in the viterbi block
#print "final state = " , enc.ST()
ntotal = dst.ntotal ()
nright = dst.nright ()
runlength = dst.runlength ()
return (ntotal,ntotal-nright)
def main(args):
nargs = len (args)
if nargs == 3:
fname=args[0]
esn0_db=float(args[1]) # Es/No in dB
rep=int(args[2]) # number of times the experiment is run to collect enough errors
else:
sys.stderr.write ('usage: test_tcm.py fsm_fname Es/No_db repetitions\n')
sys.exit (1)
# system parameters
f=trellis.fsm(fname) # get the FSM specification from a file
Kb=1024*16 # packet size in bits (make it multiple of 16 so it can be packed in a short)
bitspersymbol = int(round(math.log(f.I())/math.log(2))) # bits per FSM input symbol
K=Kb/bitspersymbol # packet size in trellis steps
modulation = fsm_utils.psk4 # see fsm_utlis.py for available predefined modulations
dimensionality = modulation[0]
constellation = modulation[1]
if len(constellation)/dimensionality != f.O():
sys.stderr.write ('Incompatible FSM output cardinality and modulation size.\n')
sys.exit (1)
# calculate average symbol energy
Es = 0
for i in range(len(constellation)):
Es = Es + constellation[i]**2
Es = Es / (len(constellation)/dimensionality)
N0=Es/pow(10.0,esn0_db/10.0); # noise variance
tot_s=0
terr_s=0
for i in range(rep):
(s,e)=run_test(f,Kb,bitspersymbol,K,dimensionality,constellation,N0,-long(666+i)) # run experiment with different seed to get different noise realizations
tot_s=tot_s+s
terr_s=terr_s+e
if (i%100==0):
print i,s,e,tot_s,terr_s, '%e' % ((1.0*terr_s)/tot_s)
# estimate of the (short) error rate
print tot_s,terr_s, '%e' % ((1.0*terr_s)/tot_s)
if __name__ == '__main__':
main (sys.argv[1:])
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