-#!/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

- s2fsmi = blocks.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 = 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

- metrics = trellis.metrics_f(f.O(),dimensionality,constellation,digital.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 = 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

- 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:])