UNB ECE4253 Digital Communications
Department of Electrical and Computer Engineering - University of New Brunswick, Fredericton, NB, Canada

Convolutional Coder (R=1/2, K=3)

This online tool passes data through this convolutional coder.


For every input bit (C) there are two output bits (XY), defining a rate one-half (R=1/2) encoder. Because output symbols (XY) are computed across three bits (the incoming bit and the two previous bits) this coder has constraint length given by (K=3). The polynomials [7,5] define the [X,Y] XOR connections (in octal).

Trellis Diagram

Input Bits (C)
trellis
Output Symbols (XY)

Input Bits:
Discussion | MATLAB

The initial state (BA) of the flip flops is assumed to be 00. Two zeros are appended to the incoming data to flush the circuit and return to the 00 state at the end.

Can the message be recovered? - Try the Viterbi Decoder with the above encoded message.

Try this same data with different encoders:

R=1/2, K=3R=1/2, K=4R=1/3, K=4R=2/3, K=3

2024-04-24 04:53:14 ADT
Last Updated: 11-09-08 		Richard Tervo [ tervo@unb.ca ] Back to the course homepage...