WSJT-X/lib/ldpc/ex-ham7a
Steven Franke 5ac886855d Add ldpc sandbox folder.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@6437 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2016-01-25 00:04:21 +00:00

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#!/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