39 lines
1.5 KiB
Plaintext
39 lines
1.5 KiB
Plaintext
|
#!/bin/sh
|
||
|
|
|
||
|
|
# Example of decoding a (7,4) Hamming code using exhaustive enumeration and
|
||
|
|
# probability propagation, with an Additive White Gaussian Noise channel with
|
||
|
|
# noise standard deviation of 0.5, for which Eb/N0 = 5.44 dB.
|
||
|
|
#
|
||
|
|
# Testing is done by transmitting zero blocks, which is sufficient because
|
||
|
|
# both the channel and the decoding procedure are symmetrical. WARNING: But
|
||
|
|
# things can easily become non-symmetrical with bugs, so this technique should
|
||
|
|
# be used with caution, and only when necessary for performance reasons.
|
||
|
|
# Decoding is done three times, once minimizing block error probability, once
|
||
|
|
# minimizing bit error probability, and once by up to 200 iterations of
|
||
|
|
# probability propagation.
|
||
|
|
|
||
|
|
set -e # Stop if an error occurs
|
||
|
|
set -v # Echo commands as they are read
|
||
|
|
|
||
|
|
make-pchk ex-ham7a.pchk 3 7 0:0 0:3 0:4 0:5 1:1 1:3 1:4 1:6 2:2 2:4 2:5 2:6
|
||
|
|
make-gen ex-ham7a.pchk ex-ham7a.gen dense
|
||
|
|
transmit 7x100000 ex-ham7a.rec 1 awgn 0.5
|
||
|
|
|
||
|
|
# DECODE BY ENUMERATION TO MINIMIZE BLOCK ERROR PROBABILITY
|
||
|
|
|
||
|
|
decode ex-ham7a.pchk ex-ham7a.rec ex-ham7a.dec-blk awgn 0.5 \
|
||
|
|
enum-block ex-ham7a.gen
|
||
|
|
verify ex-ham7a.pchk ex-ham7a.dec-blk ex-ham7a.gen
|
||
|
|
|
||
|
|
# DECODE BY ENUMERATION TO MINIMIZE BIT ERROR PROBABILITY
|
||
|
|
|
||
|
|
decode ex-ham7a.pchk ex-ham7a.rec ex-ham7a.dec-bit awgn 0.5 \
|
||
|
|
enum-bit ex-ham7a.gen
|
||
|
|
verify ex-ham7a.pchk ex-ham7a.dec-bit ex-ham7a.gen
|
||
|
|
|
||
|
|
# DECODE BY PROBABILITY PROPAGATION
|
||
|
|
|
||
|
|
decode ex-ham7a.pchk ex-ham7a.rec ex-ham7a.dec-prp awgn 0.5 \
|
||
|
|
prprp 200
|
||
|
|
verify ex-ham7a.pchk ex-ham7a.dec-prp ex-ham7a.gen
|