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#!/usr/bin/env python
from gnuradio import gr
from gnuradio import audio
from gnuradio import trellis, digital, blocks
from gnuradio import eng_notation
import math
import sys
import random
import fsm_utils
try:
from gnuradio import analog
except ImportError:
sys.stderr.write("Error: Program requires gr-analog.\n")
sys.exit(1)
def run_test(f, Kb, bitspersymbol, K, dimensionality, constellation, N0, seed):
tb = gr.top_block()
# TX
src = blocks.lfsr_32k_source_s()
src_head = blocks.head(gr.sizeof_short, Kb / 16) # packet size in shorts
# unpack shorts to symbols compatible with the FSM input cardinality
s2fsmi = blocks.packed_to_unpacked_ss(bitspersymbol, gr.GR_MSB_FIRST)
enc = trellis.encoder_ss(f, 0) # initial state = 0
mod = digital.chunks_to_symbols_sf(constellation, dimensionality)
# CHANNEL
add = blocks.add_ff()
noise = analog.noise_source_f(analog.GR_GAUSSIAN, math.sqrt(N0 / 2), seed)
# RX
# data preprocessing to generate metrics for Viterbi
metrics = trellis.metrics_f(
f.O(), dimensionality, constellation, digital.TRELLIS_EUCLIDEAN)
# Put -1 if the Initial/Final states are not set.
va = trellis.viterbi_s(f, K, 0, -1)
fsmi2s = blocks.unpacked_to_packed_ss(
bitspersymbol, gr.GR_MSB_FIRST) # pack FSM input symbols to shorts
dst = blocks.check_lfsr_32k_s()
tb.connect(src, src_head, s2fsmi, enc, mod)
tb.connect(mod, (add, 0))
tb.connect(noise, (add, 1))
tb.connect(add, metrics)
tb.connect(metrics, va, fsmi2s, dst)
tb.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
# number of times the experiment is run to collect enough errors
rep = int(args[2])
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
# packet size in bits (make it multiple of 16 so it can be packed in a short)
Kb = 1024 * 16
# bits per FSM input symbol
bitspersymbol = int(round(math.log(f.I()) / math.log(2)))
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):
# run experiment with different seed to get different noise realizations
(s, e) = run_test(f, Kb, bitspersymbol, K,
dimensionality, constellation, N0, -int(666 + i))
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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