#!/bin/sh
# this script characterizes a single code over a range of Eb/N0
# a baseband signal with mean power = 1 
# note relationship between noise standard deviation, sigma, and Eb/No:
# Eb/No = 1/(2*R*sigma^2)
# If R=1/2, then Eb/No = 1/sigma^2 
# make-ldpc ldpc.pchk "$m" "$n" $seed evenboth 2x3/8x4 no4cycle

set -e  # Stop if an error occurs
#set -v  # Echo commands as they are read

n=128
k=80
m=$((n-k))
seed=873
ntrials=1000000
niterations=10

rate=$(echo "scale=5; $k/$n" | bc)
echo n=$n k=$k rate=$rate m=$m

make-ldpc ldpc.pchk "$m" "$n" $seed evenboth 120x3/8x4 no4cycle

make-gen  ldpc.pchk ldpc.gen sparse
rand-src  ldpc.src 1 "$k"x"$ntrials"
encode    ldpc.pchk ldpc.gen ldpc.src ldpc.enc

for i in `seq -1 10`;
do
  db=$(echo "scale=5; $i/2.0" | bc)
  ebno=$(echo "scale=5; e(0.1*$db*l(10.0))" | bc -l)
  sigma=$(echo "scale=5; 1/sqrt(2*$rate*$ebno)" | bc)
  echo db $db ebno $ebno sigma $sigma

  transmit ldpc.enc ldpc.rec 1 awgn $sigma
  decode   ldpc.pchk ldpc.rec ldpc.dec awgn $sigma prprp $niterations 
  verify   ldpc.pchk ldpc.dec ldpc.gen ldpc.src
done