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,dimensionality,constellation,N0,seed): 13 fg = gr.flow_graph () 14 15 # TX 16 src = gr.lfsr_32k_source_s() 17 src_head = gr.head (gr.sizeof_short,Kb/16) # packet size in shorts 18 s2fsmi = gr.packed_to_unpacked_ss(bitspersymbol,gr.GR_MSB_FIRST) # unpack shorts to symbols compatible with the FSM input cardinality 19 enc = trellis.encoder_ss(f,0) # initial state = 0 20 mod = gr.chunks_to_symbols_sf(constellation,dimensionality) 21 22 # CHANNEL 23 add = gr.add_ff() 24 noise = gr.noise_source_f(gr.GR_GAUSSIAN,math.sqrt(N0/2),seed) 25 26 # RX 27 metrics = trellis.metrics_f(f.O(),dimensionality,constellation,trellis.TRELLIS_EUCLIDEAN) # data preprocessing to generate metrics for Viterbi 28 va = trellis.viterbi_s(f,K,0,-1) # Put -1 if the Initial/Final states are not set. 29 fsmi2s = gr.unpacked_to_packed_ss(bitspersymbol,gr.GR_MSB_FIRST) # pack FSM input symbols to shorts 30 dst = gr.check_lfsr_32k_s(); 31 32 fg.connect (src,src_head,s2fsmi,enc,mod) 33 fg.connect (mod,(add,0)) 34 fg.connect (noise,(add,1)) 35 fg.connect (add,metrics) 36 fg.connect (metrics,va,fsmi2s,dst) 37 38 fg.run() 39 40 # A bit of cheating: run the program once and print the 41 # final encoder state. 42 # Then put it as the last argument in the viterbi block 43 #print "final state = " , enc.ST() 44 45 ntotal = dst.ntotal () 46 nright = dst.nright () 47 runlength = dst.runlength () 48 return (ntotal,ntotal-nright) 49 50 51 def main(args): 52 nargs = len (args) 53 if nargs == 3: 54 fname=args[0] 55 esn0_db=float(args[1]) # Es/No in dB 56 rep=int(args[2]) # number of times the experiment is run to collect enough errors 57 else: 58 sys.stderr.write ('usage: test_tcm.py fsm_fname Es/No_db repetitions\n') 59 sys.exit (1) 60 61 # system parameters 62 f=trellis.fsm(fname) # get the FSM specification from a file 63 Kb=1024*16 # packet size in bits (make it multiple of 16 so it can be packed in a short) 64 bitspersymbol = int(round(math.log(f.I())/math.log(2))) # bits per FSM input symbol 65 K=Kb/bitspersymbol # packet size in trellis steps 66 modulation = fsm_utils.psk4 # see fsm_utlis.py for available predefined modulations 67 dimensionality = modulation[0] 68 constellation = modulation[1] 69 if len(constellation)/dimensionality != f.O(): 70 sys.stderr.write ('Incompatible FSM output cardinality and modulation size.\n') 71 sys.exit (1) 72 # calculate average symbol energy 73 Es = 0 74 for i in range(len(constellation)): 75 Es = Es + constellation[i]**2 76 Es = Es / (len(constellation)/dimensionality) 77 N0=Es/pow(10.0,esn0_db/10.0); # noise variance 78 79 tot_s=0 80 terr_s=0 81 for i in range(rep): 82 (s,e)=run_test(f,Kb,bitspersymbol,K,dimensionality,constellation,N0,-long(666+i)) # run experiment with different seed to get different noise realizations 83 tot_s=tot_s+s 84 terr_s=terr_s+e 85 if (i%100==0): 86 print i,s,e,tot_s,terr_s, '%e' % ((1.0*terr_s)/tot_s) 87 # estimate of the (short) error rate 88 print tot_s,terr_s, '%e' % ((1.0*terr_s)/tot_s) 89 90 91 if __name__ == '__main__': 92 main (sys.argv[1:])