From 77d25d75e11b7d574ab7073e1054cb25e66baa12 Mon Sep 17 00:00:00 2001
From: anastas <anastas@221aa14e-8319-0410-a670-987f0aec2ac5>
Date: Fri, 11 Aug 2006 10:57:08 +0000
Subject: Added examples for gr-trellis in
gnuradio-examples/python/channel-coding
git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@3235 221aa14e-8319-0410-a670-987f0aec2ac5
---
.../python/channel-coding/test_tcm_combined.py | 98 ++++++++++++++++++++++
1 file changed, 98 insertions(+)
create mode 100755 gnuradio-examples/python/channel-coding/test_tcm_combined.py
(limited to 'gnuradio-examples/python/channel-coding/test_tcm_combined.py')
diff --git a/gnuradio-examples/python/channel-coding/test_tcm_combined.py b/gnuradio-examples/python/channel-coding/test_tcm_combined.py
new file mode 100755
index 0000000000..01e092a0d1
--- /dev/null
+++ b/gnuradio-examples/python/channel-coding/test_tcm_combined.py
@@ -0,0 +1,98 @@
+#!/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 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,K/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
+ va = trellis.viterbi_combined_s(f,dimensionality,constellation,K/bitspersymbol,0,7,trellis.TRELLIS_EUCLIDEAN) # 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,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_combined.py fsm_fname Es/No_db repetitions\n')
+ sys.exit (1)
+
+ # system parameters
+ f=trellis.fsm(fname) # get the FSM specification from a file (will hopefully be automated in the future...)
+ Kb=1024*16 # packet size in bits (make it multiple of 16)
+ 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_utils.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) & (i>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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