1 files changed, 98 insertions, 0 deletions
diff --git a/gr-trellis/docs/test_tcm.py b/gr-trellis/docs/test_tcm.py
new file mode 100644
index 0000000000..61ab00f1c8
--- /dev/null
+++ b/gr-trellis/docs/test_tcm.py
@@ -0,0 +1,98 @@
+#!/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:])