scripts init

scripts/commpy/examples/conv_encode_decode.py

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+
+# Authors: Veeresh Taranalli <veeresht@gmail.com>
+# License: BSD 3-Clause
+
+import numpy as np
+import commpy.channelcoding.convcode as cc
+from commpy.utilities import *
+
+# =============================================================================
+# Example showing the encoding and decoding of convolutional codes
+# =============================================================================
+
+# G(D) corresponding to the convolutional encoder
+generator_matrix = np.array([[05, 07]])
+#generator_matrix = np.array([[03, 00, 02], [07, 04, 06]])
+
+# Number of delay elements in the convolutional encoder
+M = np.array([2])
+
+# Create trellis data structure
+trellis = cc.Trellis(M, generator_matrix)
+
+# Traceback depth of the decoder
+tb_depth = 5*(M.sum() + 1)
+
+for i in range(10):
+    # Generate random message bits to be encoded
+    message_bits = np.random.randint(0, 2, 1000)
+
+    # Encode message bits
+    coded_bits = cc.conv_encode(message_bits, trellis)
+
+    # Introduce bit errors (channel)
+    #coded_bits[4] = 0
+    #coded_bits[7] = 0
+
+    # Decode the received bits
+    decoded_bits = cc.viterbi_decode(coded_bits.astype(float), trellis, tb_depth)
+
+    num_bit_errors = hamming_dist(message_bits, decoded_bits[:-M])
+    #num_bit_errors = 1
+
+    if num_bit_errors !=0:
+        #print num_bit_errors, "Bit Errors found!"
+        #print message_bits
+        #print decoded_bits[tb_depth+3:]
+        #print decoded_bits
+        break
+    else:
+        print "No Bit Errors :)"
+
+#print "==== Message Bits ==="
+#print message_bits
+#print "==== Coded Bits ====="
+#print coded_bits
+#print "==== Decoded Bits ==="
+#print decoded_bits[tb_depth:]